PREAMBLE (NOT PART OF THE STANDARD)
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this legal document is hereby made available on a noncommercial basis, as it
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END OF PREAMBLE (NOT PART OF THE STANDARD)
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
EN 199318
May 2005
ICS 91.010.30
Supersedes ENV 199311:1992
Incorporating Corrigenda
December 2005 and July 2009
English version
Eurocode 3: Design of steel structures  Part 18: Design of joints
Eurocode 3: Calcul des structures en acier  Partie 18: Calcul des assemblages 
Eurocode 3: Bemessung und Konstruktion von Stahlbauten  Teil 18: Bemessung von Anschlüssen 
This European Standard was approved by CEN on 16 April 2004.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Uptodate lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
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© 2005 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members.
Ref. No. EN 199318:2005: E
1
Contents
Page 
1 
Introduction 
8 

1.1 
Scope 
8 

1.2 
Normative references 
8 

1.3 
Distinction between Principles and Application Rules 
10 

1.4 
Terms and definitions 
10 

1.5 
Symbols 
13 
2 
Basis of design 
18 

2.1 
Assumptions 
18 

2.2 
General requirements 
18 

2.3 
Applied forces and moments 
18 

2.4 
Resistance of joints 
18 

2.5 
Design assumptions 
19 

2.6 
Joints loaded in shear subject to impact, vibration and/or load reversal 
19 

2.7 
Eccentricity at intersections 
19 
3 
Connections made with bolts, rivets or pins 
20 

3.1 
Bolts, nuts and washers 
20 


3.1.1 
General 
20 


3.1.2 
Preloaded bolts 
20 

3.2 
Rivets 
20 

3.3 
Anchor bolts 
21 

3.4 
Categories of bolted connections 
21 


3.4.1 
Shear connections 
21 


3.4.2 
Tension connections 
21 

3.5 
Positioning of holes for bolts and rivets 
23 

3.6 
Design resistance of individual fasteners 
24 


3.6.1 
Bolts and rivets 
24 


3.6.2 
Injection bolts 
28 

3.7 
Group of fasteners 
29 

3.8 
Long joints 
29 

3.9 
Slipresistant connections using 8.8 or 10.9 bolts 
30 


3.9.1 
Design Slip resistance 
30 


3.9.2 
Combined tension and shear 
31 


3.9.3 
Hybrid connections 
31 

3.10 
Deductions for fastener holes 
31 


3.10.1 
General 
31 


3.10.2 
Design for block tearing 
32 


3.10.3 
Angles connected by one leg and other unsymmetrically connected members in tension 
33 


3.10.4 
Lug angles 
34 

3.11 
Prying forces 
34 

3.12 
Distribution of forces between fasteners at the ultimate limit state 
34 

3.13 
Connections made with pins 
35 


3.13.1 
General 
35 


3.13.2 
Design of pins 
35 
4 
Welded connections 
38 

4.1 
General 
38 

4.2 
Welding consumables 
38 

4.3 
Geometry and dimensions 
38 


4.3.1 
Type of weld 
38 


4.3.2 
Fillet welds 
38 


4.3.3 
Fillet welds all round 
40 


4.3.4 
Butt welds 
40 


4.3.5 
Plug welds 
41 2 


4.3.6 
Flare groove welds 
41 

4.4 
Welds with packings 
41 

4.5 
Design resistance of a fillet weld 
42 


4.5.1 
Length of welds 
42 


4.5.2 
Effective throat thickness 
42 


4.5.3 
Design Resistance of fillet welds 
42 

4.6 
Design resistance of fillet welds all round 
44 

4.7 
Design resistance of butt welds 
45 


4.7.1 
Full penetration butt welds 
45 


4.7.2 
Partial penetration butt welds 
45 


4.7.3 
Tbutt joints 
45 

4.8 
Design resistance of plug welds 
45 

4.9 
Distribution of forces 
46 

4.10 
Connections to unstiffened flanges 
46 

4.11 
Long joints 
48 

4.12 
Eccentrically loaded single fillet or singlesided partial penetration butt welds 
48 

4.13 
Angles connected by one leg 
48 

4.14 
Welding in coldformed zones 
49 
5 
Analysis, classification and modelling 
50 

5.1 
Global analysis 
50 


5.1.1 
General 
50 


5.1.2 
Elastic global analysis 
50 


5.1.3 
Rigidplastic global analysis 
51 


5.1.4 
Elastic plastic global analysis 
50 


5.1.5 
Global analysis of lattice girders 
52 

5.2 
Classification of joints 
54 


5.2.1 
General 
54 


5.2.2 
Classification by stiffness 
54 


5.2.3 
Classification by strength 
55 

5.3 
Modelling of beamtocolumn joints 
56 
6 
Structural joints connecting H or I sections 
60 

6.1 
General 
60 


6.1.1 
Basis 
60 


6.1.2 
Structural properties 
60 


6.1.3 
Basic components of a joint 
61 

6.2 
Design Resistance 
65 


6.2.1 
Internal forces 
65 


6.2.2 
Shear forces 
65 


6.2.3 
Bending moments 
66 


6.2.4 
Equivalent Tstub in tension 
67 


6.2.5 
Equivalent Tstub in compression 
70 


6.2.6 
Design Resistance of basic components 
71 


6.2.7 
Design moment resistance of beamtocolumn joints and splices 
84 


6.2.8 
Design resistance of column bases with base plates 
89 

6.3 
Rotational stiffness 
92 


6.3.1 
Basic model 
92 


6.3.2 
Stiffness coefficients for basic joint components 
94 


6.3.3 
Endplate joints with two or more boltrows in tension 
97 


6.3.4 
Column bases 
98 

6.4 
Rotation capacity 
99 


6.4.1 
General 
99 


6.4.2 
Bolted joints 
100 


6.4.3 
Welded Joints 
100 
7 
Hollow section joints 
101 

7.1 
General 
101 3 


7.1.1 
Scope 
101 


7.1.2 
Field of application 
101 

7.2 
Design 
103 


7.2.1 
General 
103 


7.2.2 
Failure modes for hollow section joints 
103 

7.3 
Welds 
107 


7.3.1 
Design resistance 
107 

7.4 
Welded joints between CHS members 
108 


7.4.1 
General 
108 


7.4.2 
Uniplanar joints 
108 


7.4.3 
Multiplanar joints 
115 

7.5 
Welded joints between CHS or RHS brace members and RHS chord members 
116 


7.5.1 
General 
116 


7.5.2 
Uniplanar joints 
117 


7.5.3 
Multiplanar joints 
128 

7.6 
Welded joints between CHS or RHS brace members and 1 or H section chords 
129 

7.7 
Welded joints between CHS or RHS brace members and channel section chord members 
132 
4
Foreword
This European Standard EN 1993, Eurocode 3: Design of steel structures, has been prepared by Technical Committee CEN/TC250 « Structural Eurocodes », the Secretariat of which is held by BSI. CEN/TC250 is responsible for all Structural Eurocodes.
This European Standard shall be given the status of a National Standard, either by publication of an identical text or by endorsement, at the latest by November 2005, and conflicting National Standards shall be withdrawn at latest by March 2010.
This Eurocode supersedes ENV 199311.
According to the CENCENELEC Internal Regulations, the National Standard Organizations of the following countries are bound to implement these European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Background to the Eurocode programme
In 1975, the Commission of the European Community decided on an action programme in the field of construction, based on article 95 of the Treaty. The objective of the programme was the elimination of technical obstacles to trade and the harmonization of technical specifications.
Within this action programme, the Commission took the initiative to establish a set of harmonized technical rules for the design of construction works which, in a first stage, would serve as an alternative to the national rules in force in the Member States and, ultimately, would replace them.
For fifteen years, the Commission, with the help of a Steering Committee with Representatives of Member States, conducted the development of the Eurocodes programme, which led to the first generation of European codes in the 1980s.
In 1989, the Commission and the Member States of the EU and EFTA decided, on the basis of an agreement^{1} between the Commission and CEN, to transfer the preparation and the publication of the Eurocodes to CEN through a series of Mandates, in order to provide them with a future status of European Standard (EN). This links de facto the Eurocodes with the provisions of all the Council’s Directives and/or Commission’s Decisions dealing with European standards (e.g. the Council Directive 89/106/EEC on construction products  CPD  and Council Directives 93/37/EEC, 92/50/EEC and 89/440/EEC on public works and services and equivalent EFTA Directives initiated in pursuit of setting up the internal market).
The Structural Eurocode programme comprises the following standards generally consisting of a number of Parts:
EN 1990 
Eurocode 0: 
Basis of Structural Design 
EN 1991 
Eurocode 1: 
Actions on structures 
EN 1992 
Eurocode 2: 
Design of concrete structures 
EN 1993 
Eurocode 3: 
Design of steel structures 
EN 1994 
Eurocode 4: 
Design of composite steel and concrete structures 
EN 1995 
Eurocode 5: 
Design of timber structures 
EN 1996 
Eurocode 6: 
Design of masonry structures 
EN 1997 
Eurocode 7: 
Geotechnical design 
EN 1998 
Eurocode 8: 
Design of structures for earthquake resistance 
EN 1999 
Eurocode 9: 
Design of aluminium structures 
^{1} Agreement between the Commission of the European Communities and the European Committee for Standardisation (CEN) concerning the work on EUROCODES for the design of building and civil engineering works (BC/CEN/03/89).
5
Eurocode standards recognize the responsibility of regulatory authorities in each Member State and have safeguarded their right to determine values related to regulatory safety matters at national level where these continue to vary from State to State.
Status and field of application of eurocodes
The Member States of the EU and EFTA recognize that Eurocodes serve as reference documents for the following purposes :
 – as a means to prove compliance of building and civil engineering works with the essential requirements of Council Directive 89/106/EEC, particularly Essential Requirement N°1  Mechanical resistance and stability – and Essential Requirement N°2 – Safety in case of fire;
 – as a basis for specifying contracts for construction works and related engineering services;
 – as a framework for drawing up harmonized technical specifications for construction products (ENs and ETAs)
The Eurocodes, as far as they concern the construction works themselves, have a direct relationship with the Interpretative Documents^{2} referred to in Article 12 of the CPD, although they are of a different nature from harmonized product standards^{3}. Therefore, technical aspects arising from the Eurocodes work need to be adequately considered by CEN Technical Committees and/or EOTA Working Groups working on product standards with a view to achieving full compatibility of these technical specifications with the Eurocodes.
The Eurocode standards provide common structural design rules for everyday use for the design of whole structures and component products of both a traditional and an innovative nature. Unusual forms of construction or design conditions are not specifically covered and additional expert consideration will be required by the designer in such cases.
National Standards implementing Eurocodes
The National Standards implementing Eurocodes will comprise the full text of the Eurocode (including any annexes), as published by CEN, which may be preceded by a National title page and National foreword, and may be followed by a National annex.
The National annex may only contain information on those parameters which are left open in the Eurocode for national choice, known as Nationally Determined Parameters, to be used for the design of buildings and civil engineering works to be constructed in the country concerned, i.e. :
 – values and/or classes where alternatives are given in the Eurocode,
 – values to be used where a symbol only is given in the Eurocode,
 – country specific data (geographical, climatic, etc.), e.g. snow map,
 – the procedure to be used where alternative procedures are given in the Eurocode.
It may contain
 – decisions on the application of informative annexes,
 – references to noncontradictory complementary information to assist the user to apply the Eurocode.
Links between Eurocodes and harmonized technical specifications (ENs and ETAs) for products
^{2} According to Art. 3.3 of the CPD, the essential requirements (ERs) shall be given concrete form in interpretative documents for the creation of the necessary links between the essential requirements and the mandates for harmonized ENs and ETAGs/ETAs.
^{3} According to An. 12 of the CPD the interpretative documents shall :
 give concrete form to the essential requirements by harmonizing the terminology and the technical bases and indicating classes or levels for each requirement where necessary ;
 indicate methods of correlating these classes or levels of requirement with the technical specifications, e.g. methods of calculation and of proof, technical rules for project design, etc. ;
 serve as a reference for the establishment of harmonized standards and guidelines for European technical approvals.
The Eurocodes, de facto, play a similar role in the field of the ER 1 and a part of ER 2.
6
There is a need for consistency between the harmonized technical specifications for construction products and the technical rules for works^{4}. Furthermore, all the information accompanying the CE Marking of the construction products which refer to Eurocodes should clearly mention which Nationally Determined Parameters have been taken into account.
National annex for EN 199318
This standard gives alternative procedures, values and recommendations with notes indicating where national choices may have to be made. The National Standard implementing EN 199318 should have a National Annex containing all Nationally Determined Parameters for the design of steel structures to be constructed in the relevant country .
National choice is allowed in EN 199318 through:
  2.2(2)
  1.2.6 (Group 6: Rivets)
  3.1.1(3)
  3.4.2(1)
  5.2.1(2)
  6.2.7.2(9)
^{4} see Art.3.3 and Art. 12 of the CPD, as well as clauses 4.2, 4.3.1, 4.3.2 and 5.2 of ID 1.
7
1 Introduction
1.1 Scope
 This part of EN 1993 gives design methods for the design of joints subject to predominantly static loading using steel grades S235, S275, S355, S420, S450 and S460 .
1.2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard, only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments).
1.2.1 Reference Standards, Group 1: Weldable structural steels
EN 100251:2004 
Hot rolled products of structural steels. General technical delivery conditions 
EN 100252:2004 
Hot rolled products of structural steels. Technical delivery conditions for nonalloy structural steels 
EN 100253:2004 
Hot rolled products of structural steels. Technical delivery conditions for normalized/normalized rolled weldable fine grain structural steels 
EN 100254:2004 
Hot rolled products of structural steels. Technical delivery conditions for thermomechanical rolled weldable fine grain structural steels 
EN 100255:2004 
Hot rolled products of structural steels. Technical delivery conditions for structural steels with improved atmospheric corrosion resistance 
EN 100256:2004 
Hot rolled products of structural steels. Technical delivery conditions for flat products of high yield strength structural steels in quenched and tempered condition 
1.2.2 Reference Standards, Group 2: Tolerances, dimensions and technical delivery conditions
EN 10029:1991 
Hot rolled steel plates 3 mm thick or above  Tolerances on dimensions, shape and mass 
EN 10034:1993 
Structural steel I and Hsections  Tolerances on shape and dimensions 
EN 10051:1991 
Continuously hotrolled uncoated plate, sheet and strip of nonalloy and alloy steels Tolerances on dimensions and shape 
EN 10055:1995 
Hot rolled steel equal flange tees with radiused root and toes  Dimensions and tolerances on shape and dimensions 
EN 100561:1995 
Structural steel equal and unequal leg angles  Part 1: Dimensions 
EN 100562:1993 
Structural steel equal and unequal leg angles  Part 2: Tolerances on shape and dimensions 
EN 10164:1993 
Steel products with improved deformation properties perpendicular to the surface of the product  Technical delivery conditions 
1.2.3 Reference Standards, Group 3: Structural hollow sections
EN 102191:1997 
Cold formed welded structural hollow sections of nonalloy and fine grain steels  Part 1: Technical delivery requirements 8 
EN 102192:1997 
Cold formed welded structural hollow sections of nonalloy and fine grain steels  Part 2: Tolerances, dimensions and sectional properties 
EN 102101:1994 
Hot finished structural hollow sections of nonalloy and fine grain structural steels  Part 1: Technical delivery requirements 
EN 102102:1997 
Hot finished structural hollow sections of nonalloy and fine grain structural steels  Part 2: Tolerances, dimensions and sectional properties 
1.2.4 Reference Standards, Group 4: Bolts, nuts and washers
EN 143991:2002 
High strength structural bolting for preloading  Part 1 : General Requirements 
EN 143992:2002 
High strength structural bolting for preloading  Part 2 : Suitability Test for preloading 
EN 143993:2002 
High strength structural bolting for preloading  Part 3 : System HR Hexagon bolt and nut assemblies 
EN 143994:2002 
High strength structural bolting for preloading  Part 4 : System HV Hexagon bolt and nut assemblies 
EN 143995:2002 
High strength structural bolting for preloading  Part 5 : Plain washers for system HR 
EN 143996:2002 
High strength structural bolting for preloading  Part 6 : Plain chamfered washers for systems HR and HV 
EN ISO 8981:1999 
Mechanical properties of fasteners made of carbon steel and alloy steel  Part 1: Bolts, screws and studs (ISO 8981:1999) 
EN 208982:1993 
Mechanical properties of fasteners  Part 2: Nuts with special proof load values  Coarse thread (ISO 8982:1992) 
EN ISO 2320:1997 
Prevailing torque type steel hexagon nuts  Mechanical and performance requirements (ISO 2320:1997) 
EN ISO 4014:2000 
Hexagon head bolts  Product grades A and B (ISO 4014:1999) 
EN ISO 4016:2000 
Hexagon head bolts  Product grade C (ISO 4016:1999) 
EN ISO 4017:2000 
Hexagon head screws  Product grades A and B (ISO 4017:1999) 
EN ISO 4018:2000 
Hexagon head screws  Product grade C (ISO 4018:1999) 
EN ISO 4032:2000 
Hexagon nuts, style 1  Product grades A and B (ISO 4032:1999) 
EN ISO 4033:2000 
Hexagon nuts, style 2  Product grades A and B (ISO 4033:1999) 
EN ISO 4034:2000 
Hexagon nuts  Product grade C (ISO 4034:1999) 
EN ISO 7040:1997 
Prevailing torque hexagon nuts (with nonmetallic insert), style 1  Property classes 5, 8 and 10 
EN ISO 7042:1997 
Prevailing torque allmetal hexagon nuts, style 2  Property classes 5, 8, 10 and 12 
EN ISO 7719:1997 
Prevailing torque type allmetal hexagon nuts, style 1  Property classes 5, 8 and 10 
ISO 286 2:1988 
ISO system of limits and fits  Part 2: Tables of standard tolerance grades and limit deviations for hole and shafts 
ISO 1891:1979 
Bolts, screws, nuts and accessories  Terminology and nomenclature  Trilingual edition 
EN ISO 7089:2000 
Plain washers  Nominal series  Product grade A 
EN ISO 7090:2000 
Plain washers, chamfered  Normal series  Product grade A 
EN ISO 7091:2000 
Plain washers  Normal series  Product grade C 
EN ISO 10511:1997 
Prevailing torque type hexagon thin nuts (with nonmetallic insert) 
EN ISO 10512:1997 
Prevailing torque type hexagon nuts thin nuts, style 1, with metric fine pitch thread  Property classes 6, 8 and 10 
EN ISO 10513:1997 
Prevailing torque type allmetal hexagon nuts, style 2, with metric fine pitch thread  Property classes 8, 10 and 12 
9
1.2.5 Reference Standards, Group 5: Welding consumable and welding
EN 12345:1998 
WeldingMultilingual terms for welded joints with illustrations. September 1998. 
EN ISO 14555:1998 
WeldingArc stud welding of metallic materials. May 1995 
EN ISO 13918:1998 
WeldingStuds for arc stud weldingJanuary 1997 
EN 2883:1992 
Specification and approval of welding procedures for metallic materials. Part 3: Welding procedure tests for arc welding of steels. 1992 
EN ISO 5817:2003 
Arcwelded joints in steel  Guidance for quality levels for imperfections 
1.2.6 Reference Standards, Group 6: Rivets
NOTE: Information may be given in the National Annex.
1.2.7 Reference Standard, Group 7: Execution of steel structures
EN 10902 
Requirements for the execution of steel structures 
1.3 Distinction between Principles and Application Rules
 The rules in EN 1990 clause 1.4 apply.
1.4 Terms and definitions
 The following terms and definitions apply:
1.4.1
basic component (of a joint)
Part of a joint that makes a contribution to one or more of its structural properties.
1.4.2
connection
Location at which two or more elements meet. For design purposes it is the assembly of the basic components required to represent the behaviour during the transfer of the relevant internal forces and moments at the connection.
1.4.3
connected member
Any member that is joined to a supporting member or element.
1.4.4
joint
Zone where two or more members are interconnected. For design purposes it is the assembly of all the basic components required to represent the behaviour during the transfer of the relevant internal forces and moments between the connected members. A beamtocolumn joint consists of a web panel and either one connection (single sided joint configuration) or two connections (double sided joint configuration), see Figure 1.1.
1.4.5
joint configuration
Type or layout of the joint or joints in a zone within which the axes of two or more interconnected members intersect, see Figure 1.2.
1.4.6
rotational capacity
10
The angle through which the joint can rotate for a given resistance level without failing.
1.4.7
rotational stiffness
The moment required to produce unit rotation in a joint.
1.4.8
structural properties (of a joint)
Resistance to internal forces and moments in the connected members, rotational stiffness and rotation capacity.
1.4.9
uniplanar joint
In a lattice structure a uniplanar joint connects members that are situated in a single plane.
Figure 1.1: Parts of a beamtocolumn joint configuration
11
Figure 1.2: Joint configurations
12
1.5 Symbols
 The following symbols are used in this Standard:
d 
is 
the nominal bolt diameter, the diameter of the pin or the diameter of the fastener; 
d_{0} 
is 
the hole diameter for a bolt, a rivet or a pin ; 
d_{o,t} 
is 
the hole size for the tension face, generally the hole diameter, but for a slotted holes perpendicular to the tension face the slot length should be used; 
d_{o,v} 
is 
the hole size for the shear face, generally the hole diameter, but for slotted holes parallel to the shear face the slot length should be used; 
d_{c} 
is 
the clear depth of the column web; 
d_{m} 
is 
the mean of the across points and across flats dimensions of the bolt head or the nut, whichever is smaller; 
f_{H,Rd} 
is 
the design value of the Hertz pressure; 
f_{ur} 
is 
the specified ultimate tensile strength of the rivet; 
e_{1} 
is 
the end distance from the centre of a fastener hole to the adjacent end of any part, measured in the direction of load transfer, see Figure 3.1; 
e_{2} 
is 
the edge distance from the centre of a fastener hole to the adjacent edge of any part, measured at right angles to the direction of load transfer, see Figure 3.1; 
e_{3} 
is 
the distance from the axis of a slotted hole to the adjacent end or edge of any part, see Figure 3.1; 
e_{4} 
is 
the distance from the centre of the end radius of a slotted hole to the adjacent end or edge of any part, see Figure 3.1; 
ℓ_{eff} 
is 
the effective length of fillet weld; 
n 
is 
the number of the friction surfaces or the number of fastener holes on the shear face; 
p_{1} 
is 
the spacing between centres of fasteners in a line in the direction of load transfer, see Figure 3.1; 
p_{1,0} 
is 
the spacing between centres of fasteners in an outer line in the direction of load transfer, see Figure 3.1; 
p_{1,i} 
is 
the spacing between centres of fasteners in an inner line in the direction of load transfer, see Figure 3.1; 
p_{2} 
is 
the spacing measured perpendicular to the load transfer direction between adjacent lines of fasteners, see Figure 3.1; 
r 
is 
the bolt row number; 

NOTE: In a bolted connection with more than one boltrow in tension, the boltrows are numbered starting from the boltrow furthest from the centre of compression. 
s_{s} 
is 
the length of stiff bearing; 
t_{a} 
is 
the thickness of the angle cleat; 
t_{fc} 
is 
the thickness of the column flange; 
t_{p} 
is 
the thickness of the plate under the bolt or the nut; 
t_{w} 
is 
the thickness of the web or bracket; 
t_{wc} 
is 
the thickness of the column web; 
A 
is 
the gross crosssection area of bolt; 
A_{0} 
is 
the area of the rivet hole; 
A_{vc} 
is 
the shear area of the column, see EN 199311; 
A_{s} 
is 
the tensile stress area of the bolt or of the anchor bolt; 13 
A_{v,eff} 
is 
the effective shear area; 
B_{p,Rd} 
is 
the design punching shear resistance of the bolt head and the nut 
E 
is 
the elastic modulus; 
F_{p,Cd} 
is 
the design preload force; 
F_{t,Ed} 
is 
the design tensile force per bolt for the ultimate limit state; 
F_{t,Rd} 
is 
the design tension resistance per bolt; 
F_{T,Rd} 
is 
the tension resistance of an equivalent Tstub flange; 
F_{v,Rd} 
is 
the design shear resistance per bolt; 
F_{b,Rd} 
is 
the design bearing resistance per bolt; 
F_{s,Rd,ser} 
is 
the design slip resistance per bolt at the serviceability limit state; 
F_{s,Rd} 
is 
the design slip resistance per bolt at the ultimate limit state; 
F_{v,Ed,ser} 
is 
the design shear force per bolt for the serviceability limit state; 
F_{v,Ed} 
is 
the design shear force per bolt for the ultimate limit state; 
M_{j,Rd} 
is 
the design moment resistance of a joint; 
S_{j} 
is 
the rotational stiffness of a joint; 
S_{j,ini} 
is 
the initial rotational stiffness of a joint; 
V_{wp,Rd} 
is 
the plastic shear resistance of a column web panel; 
z 
is 
the lever arm; 
μ 
is 
the slip factor; 
ϕ 
is 
the rotation of a joint. 
 The following standard abbreviations for hollow sections are used in section 7:
CHS for “circular hollow section”
RHS for “rectangular hollow section”, which in this context includes square hollow sections.
Figure 1.3: Gap and overlap joints
 The following symbols are used in section 7:
A_{i} 
is 
the crosssectional area of member i (i = 0, 1, 2 or 3); 
A_{v} 
is 
the shear area of the chord; 
A_{v,eff} 
is 
the effective shear area of the chord; 14 
L 
is 
the system length of a member; 
M_{ip,i,Rd} 
is 
the design value of the resistance of the joint, expressed in terms of the inplane internal moment in member i (i = 0, 1, 2 or 3); 
M_{ip,i,Ed} 
is 
the design value of the inplane internal moment in member i (i = 0, 1, 2 or 3); 
M_{op,i,Rd} 
is 
the design value of the resistance of the joint, expressed in terms of the outofplane internal moment in member i (i = 0, 1, 2 or 3); 
M_{op,i,Ed} 
is 
the design value of the outofplane internal moment in member i (i = 0, 1, 2 or 3); 
N_{i,Rd} 
is 
the design value of the resistance of the joint, expressed in terms of the internal axial force in member i (i = 0, 1, 2 or 3); 
N_{i,Ed} 
is 
the design value of the internal axial force in member i (i = 0, 1, 2 or 3); 
W_{eℓ,i} 
is 
the elastic section modulus of member i (i = 0, 1, 2 or 3); 
W_{pℓ,i} 
is 
the plastic section modulus of member i (i 0, 1, 2 or 3); 
b_{i} 
is 
the overall outofplane width of RHS member i (i 0, 1, 2 or 3); 
b_{eff} 
is 
the effective width for a brace member to chord connection; 
b_{e,ov} 
is 
the effective width for an overlapping brace to overlapped brace connection; 
b_{e,p} 
is 
the effective width for punching shear; 
b_{p} 
is 
the width of a plate; 
b_{w} 
is 
the effective width for the web of the chord; 
d_{i} 
is 
the overall diameter of CHS member i (i = 0, 1, 2 or 3); 
d_{w} 
is 
the depth of the web of an I or H section chord member; 
e 
is 
the eccentricity of a joint; 
f_{b} 
is 
the buckling strength of the chord side wall; 
f_{yi} 
is 
the yield strength of member i (i = 0, 1, 2 or 3); 
f_{y0} 
is 
the yield strength of a chord member; 
g 
is 
the gap between the brace members in a K or N joint (negative values of g represent an overlap q); the gap g is measured along the length of the connecting face of the chord, between the toes of the adjacent brace members, see Figure 1.3(a); 
h_{i} 
is 
the overall inplane depth of the crosssection of member i (i = 0, 1, 2 or 3); 
h_{z}

is 
the distance between centres of gravity of the effective width parts of a rectangular section beam connected to a I or H section column; 
k 
is 
a factor defined in the relevant table, with subscript g, m, n or p; 
ℓ 
is 
the buckling length of a member; 
p 
is 
the length of the projected contact area of the overlapping brace member onto the face of the chord, in the absence of the overlapped brace member, see Figure 1.3(b); 
q 
is 
the length of overlap, measured at the face of the chord, between the brace members in a K or N joint, see Figure 1.3(b); 
r 
is 
the root radius of an 1 or H section or the corner radius of a rectangular hollow section; 
t_{f} 
is 
the flange thickness of an I or H section; 
t_{i} 
is 
the wall thickness of member i (i = 0, 1, 2 or 3); 
t_{p} 
is 
the thickness of a plate; 
t_{w} 
is 
the web thickness of an I or H section; 
α 
is 
a factor defined in the relevant table; 
θ_{i} 
is 
the included angle between brace member i and the chord (i = 1, 2 or 3); 
k 
is 
a factor defined where it occurs; 
μ 
is 
a factor defined in the relevant table; 
φ 
is 
the angle between the planes in a multiplanar joint. 15 
 The integer subscripts used in section 7 are defined as follows:
i 
is 
an integer subscript used to designate a member of a joint, i = 0 denoting a chord and i = 1, 2 or 3 the brace members. In joints with two brace members, i = 1 normally denotes the compression brace and i = 2 the tension brace, see Figure 1.4(b). For a single brace i = 1 whether it is subject to compression or tension, see Figure 1.4(a); 
i and j 
are 
integer subscripts used in overlap type joints, i to denote the overlapping brace member and j to denote the overlapped brace member, see Figure 1.4(c). 
 The stress ratios used in section 7 are defined as follows:
n 
is 
the ratio (σ_{0,Ed}/f_{y0}) / γ_{M5} (used for RHS chords); 
n_{p} 
is 
the ratio (σ_{p,Ed}/f_{y0}) / γ_{M5} (used for CHS chords); 
σ_{0,Ed} 
is 
the maximum compressive stress in the chord at a joint; 
σ_{p,Ed} 
is 
the value of σ_{0,Ed} excluding the stress due to the components parallel to the chord axis of the axial forces in the braces at that joint, see Figure 1.4. 
 The geometric ratios used in section 7 are defined as follows:
β 
is 
the ratio of the mean diameter or width of the brace members, to that of the chord: 

 
for T, Y and X joints:


 
for K and N joints:


 
for KT joints:

β_{p} 
is 
the ratio b_{i}/b_{p}; 
γ 
is 
the ratio of the chord width or diameter to twice its wall thickness:

η 
is 
the ratio of the brace member depth to the chord diameter or width:

η_{p} 
is 
the ratio h_{i}/b_{p}; 
λ_{ov} 
is 
is the overlap ratio, expressed as a percentage (λ_{ov} = (q/p) × 100%) as shown in figure 1.3(b); 
λ_{ov,lim}

is 
the overlap for which shear between braces and chord face may become critical. 
 Other symbols are specified in appropriate clauses when they are used.
NOTE: Symbols for circular sections are given in Table 7.2.
16
Figure 1.4: Dimensions and other parameters at a hollow section lattice girder joint
17
2 Basis of design
2.1 Assumptions
 The design methods given in this part of EN 1993 assume that the standard of construction is as specified in the execution standards given in 1.2 and that the construction materials and products used are those specified in EN 1993 or in the relevant material and product specifications.
2.2 General requirements
 P All joints shall have a design resistance such that the structure is capable of satisfying all the basic design requirements given in this Standard and in EN 199311.
 The partial safety factors γ_{M} for joints are given in Table 2.1.
Table 2.1: Partial safety factors for joints
Resistance of members and crosssections 
γ_{M0}, γ_{M1} and γ_{M2} see EN 199311 
Resistance of bolts 
γ_{M2} 
Resistance of rivets 
Resistance of pins 
Resistance of welds 
Resistance of plates in bearing 
Slip resistance 

 at ultimate limit state (Category C) 
γ_{M3} 
 at serviceability limit state (Category B) 
γ_{M3,ser} 
Bearing resistance of an injection bolt 
γ_{M4} 
Resistance of joints in hollow section lattice girder 
γ_{M5} 
Resistance of pins at serviceability limit state 
γ_{M6,ser} 
Preload of high strength bolts 
γ_{M7} 
Resistance of concrete 
γ_{c} see EN 1992 
NOTE: Numerical values for γ_{M} may be defined in the National Annex. Recommended values are as follows: γ_{M2} = 1,25 ; γ_{M3} = 1,25 and γ_{M3,ser} = 1,1 ; γ_{M4} = 1,0 ; γ_{M5} = 1,0 ; γ_{M6,ser} = 1,0 ; γ_{M7} = 1,1 .
 P Joints subject to fatigue shall also satisfy the principles given in EN 19931 9.
2.3 Applied forces and moments
 P The forces and moments applied to joints at the ultimate limit state shall be determined according to the principles in EN 199311.
2.4 Resistance of joints
 The resistance of a joint should be determined on the basis of the resistances of its basic components.
 Linearelastic or elasticplastic analysis may be used in the design of joints.
18
 Where fasteners with different stiffnesses are used to carry a shear load the fasteners with the highest stiffness should be designed to carry the design load. An exception to this design method is given in 3.9.3.
2.5 Design assumptions
 P joints shall be designed on the basis of a realistic assumption of the distribution of internal forces and moments. The following assumptions shall be used to determine the distribution of forces:
 the internal forces and moments assumed in the analysis are in equilibrium with the forces and moments applied to the joints,
 each element in the joint is capable of resisting the internal forces and moments,
 the deformations implied by this distribution do not exceed the deformation capacity of the fasteners or welds and the connected parts,
 the assumed distribution of internal forces shall be realistic with regard to relative stiffnesses within the joint,
 the deformations assumed in any design model based on elasticplastic analysis are based on rigid body rotations and/or inplane deformations which are physically possible, and
 any model used is in compliance with the evaluation of test results (see EN 1990).
 The application rules given in this part satisfy 2.5(1).
2.6 Joints loaded in shear subject to impact, vibration and/or load reversal
 Where a joint loaded in shear is subject to impact or significant vibration one of the following jointing methods should be used:
  welding
  bolts with locking devices
  preloaded bolts
  injection bolts
  other types of bolt which effectively prevent movement of the connected parts
  rivets.
 Where slip is not acceptable in a joint (because it is subject to reversal of shear load or for any other reason), preloaded bolts in a Category B or C connection (see 3.4), fit bolts (see 3.6.1), rivets or welding should be used.
 For wind and/or stability bracings, bolts in Category A connections (see 3.4) may be used.
2.7 Eccentricity at intersections
 Where there is eccentricity at intersections, the joints and members should be designed for the resulting moments and forces, except in the case of particular types of structures where it has been demonstrated that it is not necessary, see 5.1.5.
 In the case of joints of angles or tees attached by either a single line of bolts or two lines of bolts any possible eccentricity should be taken into account in accordance with 2.7(1). Inplane and outofplane eccentricities should be determined by considering the relative positions of the centroidal axis of the member and of the setting out line in the plane of the connection (see Figure 2.1). For a single angle in tension connected by bolts on one leg the simplified design method given in 3.10.3 may be used.
NOTE: The effect of eccentricity on angles used as web members in compression is given in EN 199311, Annex BB 1.2.
19
Figure 2.1: Setting out lines
3 Connections made with bolts, rivets or pins
3.1 Bolts, nuts and washers
3.1.1 General
 All bolts, nuts and washers should comply with 1.2.4 Reference Standards: Group 4.
 The rules in this Standard are valid for the bolt classes given in Table 3.1.
 The yield strength f_{yb} and the ultimate tensile strength f_{ub} for bolt classes 4.6, 4.8, 5.6, 5.8, 6.8, 8.8 and 10.9 are given in Table 3.1. These values should be adopted as characteristic values in design calculations.
Table 3.1: Nominal values of the yield strength f_{yb} and the ultimate tensile strength f_{ub} for bolts
Bolt class 
4.6 
4.8 
5.6 
5.8 
6.8 
8.8 
10.9 
f_{yb} (N/mm^{2}) 
240 
320 
300 
400 
480 
640 
900 
f_{ub} (N/mm^{2}) 
400 
400 
500 
500 
600 
800 
1000 
NOTE: The National Annex may exclude certain bolt classes.
3.1.2 Preloaded bolts
 Only bolt assemblies of classes 8.8 and 10.9 conforming to the requirements given in 1.2.4 Reference Standards: Group 4 for High Strength Structural Bolting for preloading with controlled tightening in accordance with the requirements in 1.2.7 Reference Standards: Group 7 may be used as preloaded bolts.
3.2 Rivets
 The material properties, dimensions and tolerances of steel rivets should comply with the requirements given in 1.2.6 Reference Standards: Group 6.
20
3.3 Anchor bolts
 The following materials may be used for anchor bolts:
  Steel grades conforming to 1.2.1 Reference Standards: Group 1;
  Steel grades conforming to 1.2.4 Reference Standards: Group 4;
  Steel grades used for reinforcing bars conforming to EN 10080;
provided that the nominal yield strength does not exceed 640 N/mm^{2} when the anchor bolts are required to act in shear and not more than 900 N/mm^{2} otherwise.
3.4 Categories of bolted connections
3.4.1 Shear connections
 Bolted connections loaded in shear should be designed as one of the following:
 Category A: Bearing type
In this category bolts from class 4.6 up to and including class 10.9 should be used. No preloading and special provisions for contact surfaces are required. The design ultimate shear load should not exceed the design shear resistance, obtained from 3.6, nor the design bearing resistance, obtained from 3.6 and 3.7.
 Category B: Slipresistant at serviceability limit state
In this category preloaded bolts in accordance with 3.1.2(1) should be used. Slip should not occur at the serviceability limit state. The design serviceability shear load should not exceed the design slip resistance, obtained from 3.9. The design ultimate shear load should not exceed the design shear resistance, obtained from 3.6, nor the design bearing resistance, obtained from 3.6 and 3.7.
 Category C: Slipresistant at ultimate limit state
In this category preloaded bolts in accordance with 3.1.2(1) should be used. Slip should not occur at the ultimate limit state. The design ultimate shear load should not exceed the design slip resistance, obtained from 3.9, nor the design bearing resistance, obtained from 3.6 and 3.7. In addition for a connection in tension, the design plastic resistance of the net crosssection at bolt holes N_{net,Rd}, (see 6.2 of EN 199311), should be checked, at the ultimate limit state.
The design checks for these connections are summarized in Table 3.2.
3.4.2 Tension connections
 Bolted connection loaded in tension should be designed as one of the following:
 Category D: nonpreloaded
In this category bolts from class 4.6 up to and including class 10.9 should be used. No preloading is required. This category should not be used where the connections are frequently subjected to variations of tensile loading. However, they may be used in connections designed to resist normal wind loads.
 Category E: preloaded
In this category preloaded 8.8 and 10.9 bolts with controlled tightening in conformity with 1.2.7 Reference Standards: Group 7 should be used.
The design checks for these connections are summarized in Table 3.2.
21
Table 3.2: Categories of bolted connections
Category 
Criteria 
Remarks 
Shear connections 
A bearing type 
F_{v,Ed} F_{v,Ed} 
≤ ≤ 
F_{v,Rd} F_{b,Rd} 
No preloading required. Bolt classes from 4.6 to 10.9 may be used. 
B slipresistant at serviceability 
F_{v,Ed,ser} F_{v,Ed} F_{v,Ed} 
≤ ≤ ≤ 
F_{s,Rd,ser} F_{v,Rd} F_{b,Rd} 
Preloaded 8.8 or 10.9 bolts should be used. For slip resistance at serviceability see 3.9. 
C slipresistant at ultimate 
F_{v,Ed} F_{v,Ed} 
≤ ≤ 
F_{s,Rd} F_{b,Rd} 
Preloaded 8.8 or 10.9 bolts should be used. For slip resistance at ultimate see 3.9. N_{net,Rd} see 3.4.1(1) c). 
Σ F_{v,Ed} ≤ N_{net,Rd} 
Tension connections 
D nonpreloaded 
F_{t,Ed} F_{t,Ed} 
≤ ≤ 
F_{t,Rd} B_{p,Rd} 
No preloading required. Bolt classes from 4.6 to 10.9 may be used. B_{p,Rd} see Table 3.4. 
E preloaded 
F_{t,Ed} F_{t,Ed} 
≤ ≤ 
F_{t,Rd} B_{p,Rd} 
Preloaded 8.8 or 10.9 bolts should be used. B_{p,Rd} see Table 3.4. 
The design tensile force F_{t,Ed} should include any force due to prying action, see 3.11. Bolts subjected to both shear force and tensile force should also satisfy the criteria given in Table 3.4. 
NOTE: If preload is not explicitly used in the design calculations for slip resistances but is required for execution purposes or as a quality measure (e.g. for durability) then the level of preload can be specified in the National Annex.
22
3.5 Positioning of holes for bolts and rivets
 Minimum and maximum spacing and end and edge distances for bolts and rivets are given in Table 3.3.
 Minimum and maximum spacing, end and edge distances for structures subjected to fatigue, see EN 199319.
Table 3.3: Minimum and maximum spacing, end and edge distances
Distances and spacings, see Figure 3.1 
Minimum 
Maximum^{1)2)3)} 
Structures made from steels conforming to EN 10025 except steels conforming to EN 100255 
Structures made from steels conforming to EN 100255 
Steel exposed to the weather or other corrosive influences 
Steel not exposed to the weather or other corrosive influences 
Steel used unprotected 
End distance e_{1} 
1,2d_{0} 
4t + 40 mm 

The larger of 8t or 125 mm 
Edge distance e_{2} 
1,2d_{0} 
4t + 40 mm 

The larger of 8t or 125 mm 
Distance e_{3} in slotted holes 
1,5d_{0}^{4)} 



Distance e_{4} in slotted holes 
1,5d_{0}^{4)} 



Spacing p_{1} 
2,2d_{0} 
The smaller of 14t or 200 mm 
The smaller of 14t or 200 mm 
The smaller of 14t_{min} or 175 mm 
Spacing p_{1,0} 

The smaller of 14t or 200 mm 


Spacing p_{1,i} 

The smaller of 28t or 400 mm 


Spacing p_{2} ^{5)} 
2,4d_{0} 
The smaller of 14t or 200 mm 
The smaller of 14t or 200 mm 
The smaller of 14t_{min} or 175 mm 
^{1)} Maximum values for spacings, edge and end distances are unlimited, except in the following cases:
  for compression members in order to avoid local buckling and to prevent corrosion in exposed members (the limiting values are given in the table) and;
  for exposed tension members to prevent corrosion (the limiting values are given in the table).
^{2)} The local buckling resistance of the plate in compression between the fasteners should be calculated according to EN 199311 using 0,6 p_{1} as buckling length. Local buckling between the fasteners need not to be checked if p_{1}/t is smaller than 9 ε . The edge distance should not exceed the local buckling requirements for an outstand element in the compression members, see EN 199311. The end distance is not affected by this requirement.
^{3)} t is the thickness of the thinner outer connected part.
^{4)} The dimensional limits for slotted holes are given in 1.2.7 Reference Standards: Group 7.
^{5)} For staggered rows of fasteners a minimum line spacing of p_{2} = 1,2d_{0} may be used, provided that the minimum distance, L, between any two fasteners is greater or equal than 2,4d_{0}, see Figure 3.1b).

23
Figure 3.1: Symbols for end and edge distances and spacing of fasteners
3.6 Design resistance of individual fasteners
3.6.1 Bolts and rivets
 The design resistance for an individual fastener subjected to shear and/or tension is given in Table 3.4.
 For preloaded bolts in accordance with 3.1.2(1) the design preload, F_{p,Cd} ,to be used in design calculations should be taken as:
F_{p,Cd} = 0,7 f_{ub} A_{s} / γ_{M7} … (3.1)
NOTE: Where the preload is not used in design calculations see note to Table 3.2.
 The design resistances for tension and for shear through the threaded portion of a bolt given in Table 3.4 should only be used for bolts manufactured in conformity with 1.2.4 Reference Standard: Group 4. 24 For bolts with cut threads, such as anchor bolts or tie rods fabricated from round steel bars where the threads comply with EN 1090, the relevant values from Table 3.4 should be used. For bolts with cut threads where the threads do not comply with EN 1090 the relevant values from Table 3.4 should be multiplied by a factor of 0,85.
 The design shear resistance F_{v,Rd} given in Table 3.4 should only be used where the bolts are used in holes with nominal clearances not exceeding those for normal holes as specified in 1.2.7 Reference Standards: Group 7.
 M12 and M14 bolts may also be used in 2 mm clearance holes provided that the design resistance of the bolt group based on bearing is less than or equal to the design resistance of the bolt group based on bolt shear. In addition for class 4.8, 5.8, 6.8, 8.8 and 10.9 bolts the design shear resistance F_{v,Rd} should be taken as 0,85 times the value given in Table 3.4.
 Fit bolts should be designed using the method for bolts in normal holes.
 The thread of a fit bolt should not be included in the shear plane.
 The length of the threaded portion of a fit bolt included in the bearing length should not exceed 1/3 of the thickness of the plate, see Figure 3.2.
 The hole tolerance used for fit bolts should be in accordance with 1.2.7 Reference Standards: Group 7.
 In single lap joints with only one bolt row, see Figure 3.3, the bolts should be provided with washers under both the head and the nut. The design bearing resistance F_{b,Rd} for each bolt should be limited to:
F_{b,Rd} ≤ 1,5 f_{u} d t / γ_{M2} … (3.2)
NOTE: Single rivets should not be used in single lap joints.
 In the case of class 8.8 or 10.9 bolts, hardened washers should be used for single lap joints with only one bolt or one row of bolts.
 Where bolts or rivets transmitting load in shear and bearing pass through packing of total thickness t_{p} greater than onethird of the nominal diameter d, see Figure 3.4, the design shear resistance F_{v,Rd} calculated as specified in Table 3.4, should be multiplying by a reduction factor β_{p} given by:
 For double shear connections with packing on both sides of the splice, t_{p} should be taken as the thickness of the thicker packing.
 Riveted connections should be designed to transfer shear forces. If tension is present the design tensile force F_{t,Ed} should not exceed the design tension resistance F_{t,Rd} given in Table 3.4.
 For grade S 235 steel the “as driven” value of f_{ur} may be taken as 400 N/mm^{2}.
 As a general rule, the grip length of a rivet should not exceed 4,5d for hammer riveting and 6,5d for press riveting.
25
Figure 3.2: Threaded portion of the shank in the bearing length for fit bolts
Figure 3.3: Single lap joint with one row of bolts
Figure 3.4: Fasteners through packing
26
Table 3.4: Design resistance for individual fasteners subjected to shear and/or tension
Failure mode 
Bolts 
Rivets 
Shear resistance per shear plane 
  where the shear plane passes through the threaded portion of the bolt (A is the tensile stress area of the bolt A_{s}):
  for classes 4.6, 5.6 and 8.8:
α_{v} = 0,6
  for classes 4.8, 5.8, 6.8 and 10.9:
α_{v} = 0,5
  where the shear plane passes through the unthreaded portion of the bolt (A is the gross cross section of the bolt): α_{v} = 0,6


Bearing resistance ^{1), 2), 3)} 
where α_{b} is the smallest of α_{d} ; or 1,0; in the direction of load transfer:
  for end bolts: ; for inner bolts:
perpendicular to the direction of load transfer:
  for edge bolts: k_{1} is the smallest of and 2,5
  for inner bolts: k_{1} is the smallest of or 2,5

Tension resistance ^{2)} 
where k_{2} = 0,63 for countersunk bolt,
otherwise k_{2} = 0,9.


Punching shear resistance 
B_{p,Rd} = 0,6 π d_{m} t_{p} f_{u} / γ_{M2} 
No check needed 
Combined shear and tension 

^{l)} The bearing resistance F_{b,Rd} for bolts
 – in oversized holes is 0,8 times the bearing resistance for bolts in normal holes.
 – in slotted holes, where the longitudinal axis of the slotted hole is perpendicular to the direction of the force transfer, is 0,6 times the bearing resistance for bolts in round, normal holes.
^{2)} For countersunk bolt:
 – the bearing resistance F_{b,Rd} should be based on a plate thickness t equal to the thickness of the connected plate minus half the depth of the countersinking.
 – for the determination of the tension resistance F_{t,Rd} the angle and depth of countersinking should conform with 1.2.4 Reference Standards: Group 4, otherwise the tension resistance F_{t,Rd} should be adjusted accordingly.
^{3)} When the load on a bolt is not parallel to the edge, the bearing resistance may be verified separately for the bolt load components parallel and normal to the end.

27
3.6.2 Injection bolts
3.6.2.1 General
 Injection bolts may be used as an alternative to ordinary bolts and rivets for category A, B and C connections specified in 3.4.
 Fabrication and erection details for injection bolts are given in 1.2.7 Reference Standards: Group 7.
3.6.2.2 Design resistance
 The design method given in 3.6.2.2(2) to 3.6.2.2(6) should be used for connections with injection bolts of class 8.8 or 10.9. Bolt assemblies should conform with the requirements given in 1.2.4 Reference Standards: Group 4, but see 3.6.2.2(3) for when preloaded bolts are used.
 The design ultimate shear load of any bolt in a Category A connection should not exceed the smaller of the following: the design shear resistance of the bolt or a group of bolts as obtained from 3.6 and 3.7; the design bearing resistance of the resin as obtained from 3.6.2.2(5).
 Preloaded injection bolts should be used for category B and C connections, for which preloaded bolt assemblies in accordance with 3.1.2(1) should be used.
 The design serviceability shear load of any bolt in a category B connection and the design ultimate shear load of any bolt in a category C connection should not exceed the design slip resistance of the bolt as obtained from 3.9 at the relevant limit state plus the design bearing resistance of the resin as obtained from 3.6.2.2(5) at the relevant limit state. In addition the design ultimate shear load of a bolt in a category B or C connection should not exceed either the design shear resistance of the bolt as obtained from 3.6, nor the design bearing resistance of the bolt as obtained from 3.6 and 3.7.
 The design bearing resistance of the resin, F_{b,Rd,resin}, may be determined according to the following equation:
where
F_{b,Rd,resin} 
is the bearing strength of an injection bolt 
β 
is a coefficient depending of the thickness ratio of the connected plates as given in Table 3.5 and Figure 3.5 
f_{b,resin} 
is the bearing strength of the resin to be determined according to the 1.2.7 Reference Standards: Group 7. 
t_{b,resin} 
is the effective bearing thickness of the resin, given in Table 3.5 
k_{t} 
is 1,0 for serviceability limit state (long duration) is 1,2 for ultimate limit state 
k_{s} 
is taken as 1,0 for holes with normal clearances or (1,0  0,1 m), for oversized holes 
m 
is the difference (in mm) between the normal and oversized hole dimensions. In the case of short slotted holes as specified in 1.2.7 Reference Standards: Group 7, m = 0, 5 · (the difference (in mm) between the hole length and width). 
 When calculating the bearing resistance of a bolt with a clamping length exceeding 3d, a value of not more than 3d should be taken to determine the effective bearing thickness t_{b,resin}(see Figure 3.6).
28
Figure 3.5: Factor β as a function of the thickness ratio of the connected plates
Table 3.5: Values of β and t_{b,resin}
t_{1} / t_{2} 
β 
t_{b,resin} 
≥ 2,0 
1,0 
2 t_{2} ≤ 1,5 d 
1,0 < t_{1} / t_{2} < 2,0 
1,66  0,33 (t_{1} / t_{2}) 
t_{1} ≤ 1,5d 
≤ 1,0 
1,33 
t_{1} ≤ 1,5d 
Figure 3.6: Limiting effective length for long injection bolts
3.7 Group of fasteners
 The design resistance of a group of fasteners may be taken as the sum of the design bearing resistances F_{b,Rd} of the individual fasteners provided that the design shear resistance F_{v,Rd} of each individual fastener is greater than or equal to the design bearing resistance F_{b,Rd}. Otherwise the design resistance of a group of fasteners should be taken as the number of fasteners multiplied by the smallest design resistance of any of the individual fasteners.
3.8 Long joints
 Where the distance L_{j} between the centres of the end fasteners in a joint, measured in the direction of force transfer (see Figure 3.7), is more than 15 d, the design shear resistance F_{v,Rd} of all the fasteners calculated according to Table 3.4 should be reduced by multiplying it by a reduction factor β_{Lf}, given by:
29
but β_{Lf} ≤ 1,0 and β_{Lf} ≥ 0,75
 The provision in 3.8(1) does not apply where there is a uniform distribution of force transfer over the length of the joint, e.g. the transfer of shear force between the web and the flange of a section.
Figure 3.7: Long joints
3.9 Slipresistant connections using 8.8 or 10.9 bolts
3.9.1 Design Slip resistance
 The design slip resistance of a preloaded class 8.8 or 10.9 bolt should be taken as:
where:
k_{s} 
is 
given in Table 3.6 
n 
is 
the number of the friction planes 
μ 
is 
the slip factor obtained either by specific tests for the friction surface in accordance with 1.2.7 Reference Standards: Group 7 or when relevant as given in Table 3.7. 
 For class 8.8 and 10.9 bolts conforming with 1.2.4 Reference Standards: Group 4, with controlled tightening in conformity with 1.2.7 Reference Standards: Group 7, the preloading force F_{p,C} to be used in equation (3.6) should be taken as:
F_{p,C} = 0,7 f_{ub} A_{s} … (3.7)
Table 3.6: Values of k_{s}
Description 
k_{s} 
Bolts in normal holes. 
1,0 
Bolts in either oversized holes or short slotted holes with the axis of the slot perpendicular to the direction of load transfer. 
0,85 
Bolts in long slotted holes with the axis of the slot perpendicular to the direction of load transfer. 
0,7 
Bolts in short slotted holes with the axis of the slot parallel to the direction of load transfer. 
0,76 
Bolts in long slotted holes with the axis of the slot parallel to the direction of load transfer. 
0,63 
30
Table 3.7: Slip factor, μ, for preloaded bolts
Class of friction surfaces (see 1.2.7 Reference Standard: Group 7) 
Slip factor μ 
A 
0,5 
B 
0,4 
C 
0,3 
D 
0,2 
NOTE 1: The requirements for testing and inspection are given in 1.2.7 Reference Standards: Group 7.
NOTE 2: The classification of any other surface treatment should be based on test specimens representative of the surfaces used in the structure using the procedure set out in 1.2.7 Reference Standards: Group 7.
NOTE 3: The definitions of the class of friction surface are given in 1.2.7 Reference Standards: Group 7.
NOTE 4: With painted surface treatments a loss of preload may occur over time.

3.9.2 Combined tension and shear
 If a slipresistant connection is subjected to an applied tensile force, F_{t,Ed} or F_{t,Ed,ser}, in addition to the shear force, F_{v,Ed} or F_{v,Ed,ser}, tending to produce slip, the design slip resistance per bolt should be taken as follows:
for a category B connection:
for a category C connection:
 If, in a moment connection, a contact force on the compression side counterbalances the applied tensile force no reduction in slip resistance is required.
3.9.3 Hybrid connections
 As an exception to 2.4(3), preloaded class 8.8 and 10.9 bolts in connections designed as slipresistant at the ultimate limit state (Category C in 3.4) may be assumed to share load with welds, provided that the final tightening of the bolts is carried out after the welding is complete.
3.10 Deductions for fastener holes
3.10.1 General
 Deduction for holes in the member design should be made according to EN 199311.
31
3.10.2 Design for block tearing
 Block tearing consists of failure in shear at the row of bolts along the shear face of the hole group accompanied by tensile rupture along the line of bolt holes on the tension face of the bolt group. Figure 3.8 shows block tearing.
 For a symmetric bolt group subject to concentric loading the design block tearing resistance, V_{eff,1,Rd} is given by:
V_{eff,1,Rd} = f_{u} A_{nt} / γ_{M2} + (1 / √3) f_{y} A_{nv} / γ_{M0} … (3.9)
where
A_{nt} 
is 
net area subjected to tension; 
A_{nv} 
is 
net area subjected to shear. 
 For a bolt group subject to eccentric loading the design block shear tearing resistance V_{eff,2,Rd} is given by:
V_{eff,2,Rd} = 0,5 f_{u} A_{nt} / γ_{M2} + (1 / √3) f_{y} A_{nv} / γ_{M0} … (3.10)
Figure 3.8: Block tearing
32
3.10.3 Angles connected by one leg and other unsymmetrically connected members in tension
 The eccentricity in joints, see 2.7(1), and the effects of the spacing and edge distances of the bolts, should be taken into account in determining the design resistance of:
 – unsymmetrical members;
 – symmetrical members that are connected unsymmetrically, such as angles connected by one leg.
 A single angle in tension connected by a single row of bolts in one leg, see Figure 3.9, may be treated as concentrically loaded over an effective net section for which the design ultimate resistance should be determined as follows:
with 1 bolt:
with 2 bolts:
with 3 or more bolts:
where:
β_{2} and β_{3} 
are reduction factors dependent on the pitch p_{1} as given in Table 3.8. For intermediate values of p_{1} the value of β may be determined by linear interpolation; 
A_{net} 
is the net area of the angle. For an unequalleg angle connected by its smaller leg, A_{net} should be taken as equal to the net section area of an equivalent equalleg angle of leg size equal to that of the smaller leg. 
Table 3.8: Reduction factors β_{2} and β_{3}
Pitch 
p_{1} 
≤ 2,5 d_{o} 
≥ 5,0 d_{o} 
2 bolts 
β_{2} 
0,4 
0,7 
3 bolts or more 
β_{3} 
0,5 
0,7 
Figure 3.9: Angles connected by one leg
33
3.10.4 Lug angles
 The Lug angle shown in Figure 3.10 connects angle members and their fasteners to a gusset or other supporting part and should be designed to transmit a force 1,2 times the force in the outstand of the angle connected.
 The fasteners connecting the lug angle to the outstand of the angle member should be designed to transmit a force 1,4 times the force in the outstand of the angle member.
 Lug angles connecting a channel or a similar member should be designed to transmit a force 1,1 times the force in the channel flanges to which they are attached.
 The fasteners connecting the lug angle to the channel or similar member should be designed to transmit a force 1,2 times the force in the channel flange which they connect.
 In no case should less than two bolts or rivets be used to attach a lug angle to a gusset or other supporting part.
 The connection of a lug angle to a gusset plate or other supporting part should terminate at the end of the member connected. The connection of the lug angle to the member should run from the end of the member to a point beyond the direct connection of the member to the gusset or other supporting part.
Figure 3.10: Lug angles
3.11 Prying forces
 Where fasteners are required to carry an applied tensile force, they should be designed to resist the additional force due to prying action, where this can occur.
NOTE: The rules given in 6.2.4 implicitly account for prying forces.
3.12 Distribution of forces between fasteners at the ultimate limit state
 When a moment is applied to a joint, the distribution of internal forces may be either linear (i.e. proportional to the distance from the centre of rotation) or plastic, (i.e. any distribution that is in equilibrium is acceptable provided that the resistances of the components are not exceeded and the ductility of the components is sufficient).
 The elastic linear distribution of internal forces should be used for the following:
 – when bolts are used creating a category C slipresistant connection,
 – in shear connections where the design shear resistance F_{v,Rd} of a fastener is less than the design bearing resistance F_{b,Rd},
 – where connections are subjected to impact, vibration or load reversal (except wind loads).
 When a joint is loaded by a concentric shear only, the load may be assumed to be uniformly distributed amongst the fasteners, provided that the size and the class of fasteners is the same.
34
3.13 Connections made with pins
3.13.1 General
 Wherever there is a risk of pins becoming loose, they should be secured.
 Pin connections in which no rotation is required may be designed as single bolted connections, provided that the length of the pin is less than 3 times the diameter of the pin, see 3.6.1. For all other cases the method given in 3.13.2 should be followed.
 In pinconnected members the geometry of the unstiffnened element that contains a hole for the pin should satisfy the dimensional requirements given in Table 3.9.
Table 3.9: Geometrical requirements for pin ended members
Type A: Given thickness t

Type B: Given geometry

 Pin connected members should be arranged such to avoid eccentricity and should be of sufficient size to distribute the load from the area of the member with the pin hole into the member away from the pin.
3.13.2 Design of pins
 The design requirements for solid circular pins are given in Table 3.10.
 The moments in a pin should be calculated on the basis that the connected parts form simple supports. It should be generally assumed that the reactions between the pin and the connected parts are uniformly distributed along the length in contact on each part as indicated in Figure 3.11.
 If the pin is intended to be replaceable, in addition to the provisions given in 3.13.1 to 3.13.2, the contact bearing stress should satisfy:
σ_{h,Ed} ≤ f_{h,Rd} … (3.14)
where:
35
f_{h,Rd} = 2,5 f_{y}/γ_{M6,ser} … (3.16)
where:
d 
is 
the diameter of the pin; 
d_{0} 
is 
the diameter of the pin hole; 
F_{b,Ed,Ser} 
is 
the design value of the force to be transferred in bearing, under the characteristic load combination for serviceability limit states. 
Table 3.10: Design criteria for pin connections
Failure mode 
Design requirements 
Shear resistance of the pin 
F_{v,Rd} 
= 0,6 A f_{up} / γ_{M2} 
≥ 
F_{v,Ed} 
Bearing resistance of the plate and the pin 
F_{b,Rd} 
= 1,5 t d f_{y} / γ_{M0} 
≥ 
F_{b,Ed} 
If the pin is intended to be replaceable this requirement should also be satisfied. 
F_{b,Rd,ser} 
= 0,6 t d f_{y} / γ_{M6,ser} 
≥ 
F_{b,Ed,ser} 
Bending resistance of the pin 
M_{Rd} 
= 1,5 W_{eℓ} f_{yp}/γ_{M0} 
≥ 
M_{Ed} 
If the pin is intended to be replaceable this requirement should also be satisfied. 
M_{Rd,ser} 
= 0,8 W_{eℓ} f_{yp}/γ_{M6,ser} 
≥ 
M_{Ed,ser} 
Combined shear and bending resistance of the pin 

d 
is 
the diameter of the pin; 
f_{y} 
is 
the lower of the yield strengths of the pin and the connected part; 
f_{up} 
is 
the ultimate tensile strength of the pin; 
f_{yp} 
is 
the yield strength of the pin; 
t 
is 
the thickness of the connected part; 
A 
is 
the crosssectional area of a pin. 

36
Figure 3.11: Bending moment in a pin
37
4 Welded connections
4.1 General
 The provisions in this section apply to weldable structural steels conforming to EN 199311 and to material thicknesses of 4 mm and over. The provisions also apply to joints in which the mechanical properties of the weld metal are compatible with those of the parent metal, see 4.2.
For welds in thinner material reference should be made to EN 1993 part 1.3 and for welds in structural hollow sections in material thicknesses of 2,5 mm and over guidance is given section 7 of this Standard.
For stud welding reference should be made to EN 199411.
NOTE: Further guidance on stud welding can be found in EN ISO 14555 and EN ISO 13918.
 P Welds subject to fatigue shall also satisfy the principles given in EN 199319.
 Quality level C according to EN ISO 25817 is usually required, if not otherwise specified. The frequency of inspection of welds should be specified in accordance with the rules in 1.2.7 Reference Standards: Group 7. The quality level of welds should be chosen according to EN ISO 25817. For the quality level of welds used in fatigue loaded structures, see EN 199319.
 Lamellar tearing should be avoided.
 Guidance on lamellar tearing is given in EN 19931 10.
4.2 Welding consumables
 All welding consumables should conform to the relevant standards specified in 1.2.5 Reference Standards; Group 5.
 The specified yield strength, ultimate tensile strength, elongation at failure and minimum Charpy Vnotch energy value of the filler metal, should be equivalent to, or better than that specified for the parent material.
NOTE: Generally it is safe to use electrodes that are overmatched with regard to the steel grades being used.
4.3 Geometry and dimensions
4.3.1 Type of weld
 This Standard covers the design of fillet welds, fillet welds all round, butt welds, plug welds and flare groove welds. Butt welds may be either full penetration butt welds or partial penetration butt welds. Both fillet welds all round and plug welds may be either in circular holes or in elongated holes.
 The most common types of joints and welds are illustrated in EN 12345.
4.3.2 Fillet welds
4.3.2.1 General
 Fillet welds may be used for connecting parts where the fusion faces form an angle of between 60° and 120°.
38
 Angles smaller than 60° are also permitted. However, in such cases the weld should be considered to be a partial penetration butt weld.
 For angles greater than 120° the resistance of fillet welds should be determined by testing in accordance with EN 1990 Annex D: Design by testing.
 Fillet welds finishing at the ends or sides of parts should be returned continuously, full size, around the corner for a distance of at least twice the leg length of the weld, unless access or the configuration of the joint renders this impracticable.
NOTE: In the case of intermittent welds this rule applies only to the last intermittent fillet weld at corners.
 End returns should be indicated on the drawings.
 For eccentricity of singlesided fillet welds, see 4.12.
4.3.2.2 intermittent fillet welds
 Intermittent fillet welds should not be used in corrosive conditions.
 In an intermittent fillet weld, the gaps (L_{1} or L_{2}) between the ends of each length of weld L_{w} should fulfil the requirement given in Figure 4.1.
 In an intermittent fillet weld, the gap (L_{1} or L_{2}) should be taken as the smaller of the distances between the ends of the welds on opposite sides and the distance between the ends of the welds on the same side.
 In any run of intermittent fillet weld there should always be a length of weld at each end of the part connected.
 In a builtup member in which plates are connected by means of intermittent fillet welds, a continuous fillet weld should be provided on each side of the plate for a length at each end equal to at least threequarters of the width of the narrower plate concerned (see Figure 4.1).
39
Figure 4.1: Intermittent fillet welds
4.3.3 Fillet welds all round
 Fillet welds all round, comprising fillet welds in circular or elongated holes, may be used only to transmit shear or to prevent the buckling or separation of lapped parts.
 The diameter of a circular hole, or width of an elongated hole, for a fillet weld all round should not be less than four times the thickness of the part containing it.
 The ends of elongated holes should be semicircular, except for those ends which extend to the edge of the part concerned.
 The centre to centre spacing of fillet welds all round should not exceed the value necessary to prevent local buckling, see Table 3.3.
4.3.4 Butt welds
 A full penetration butt weld is defined as a weld that has complete penetration and fusion of weld and parent metal throughout the thickness of the joint.
40
 A partial penetration butt weld is defined as a weld that has joint penetration which is less than the full thickness of the parent material.
 Intermittent butt welds should not be used.
 For eccentricity in singlesided partial penetration butt welds, see 4.12.
4.3.5 Plug welds
 Plug welds may be used:
  to transmit shear,
  to prevent the buckling or separation of lapped parts, and
  to interconnect the components of builtup members
but should not be used to resist externally applied tension.
 The diameter of a circular hole, or width of an elongated hole, for a plug weld should be at least 8 mm more than the thickness of the part containing it.
 The ends of elongated holes should either be semicircular or else should have corners which are rounded to a radius of not less than the thickness of the part containing the slot, except for those ends which extend to the edge of the part concerned.
 The thickness of a plug weld in parent material up to 16 mm thick should be equal to the thickness of the parent material. The thickness of a plug weld in parent material over 16 mm thick should be at least half the thickness of the parent material and not less than 16 mm.
 The centre to centre spacing of plug welds should not exceed the value necessary to prevent local buckling, see Table 3.3.
4.3.6 Flare groove welds
 For solid bars the design effective throat thickness of flare groove welds, when fitted flush to the surface of the solid section of the bars, is defined in Figure 4.2. The definition of the design throat thickness of flare groove welds in rectangular hollow sections is given in 7.3.1(7).
Figure 4.2: Effective throat thickness of flare groove welds in solid sections
4.4 Welds with packings
 In the case of welds with packing, the packing should be trimmed flush with the edge of the part that is to be welded.
 Where two parts connected by welding are separated by packing having a thickness less than the leg length of weld necessary to transmit the force, the required leg length should be increased by the thickness of the packing.
41
 Where two parts connected by welding are separated by packing having a thickness equal to, or greater than, the leg length of weld necessary to transmit the force, each of the parts should be connected to the packing by a weld capable of transmitting the design force.
4.5 Design resistance of a fillet weld
4.5.1 Length of welds
 The effective length of a fillet weld l_{eff} should be taken as the length over which the fillet is fullsize. This maybe taken as the overall length of the weld reduced by twice the effective throat thickness a. Provided that the weld is full size throughout its length including starts and terminations, no reduction in effective length need be made for either the start or the termination of the weld.
 A fillet weld with an effective length less than 30 mm or less than 6 times its throat thickness, whichever is larger, should not be designed to carry load.
4.5.2 Effective throat thickness
 The effective throat thickness, a, of a fillet weld should be taken as the height of the largest triangle (with equal or unequal legs) that can be inscribed within the fusion faces and the weld surface, measured perpendicular to the outer side of this triangle, see Figure 4.3.
 The effective throat thickness of a fillet weld should not be less than 3 mm.
 In determining the design resistance of a deep penetration fillet weld, account may be taken of its additional throat thickness, see Figure 4.4, provided that preliminary tests show that the required penetration can consistently be achieved.
Figure 4.3: Throat thickness of a fillet weld
Figure 4.4: Throat thickness of a deep penetration fillet weld
4.5.3 Design Resistance of fillet welds
4.5.3.1 General
 The design resistance of a fillet weld should be determined using either the Directional method given in 4.5.3.2 or the Simplified method given in 4.5.3.3.
42
4.5.3.2 Directional method
 In this method, the forces transmitted by a unit length of weld are resolved into components parallel and transverse to the longitudinal axis of the weld and normal and transverse to the plane of its throat.
 The design throat area A_{w} should be taken as A_{w} = ∑a ℓ_{eff}.
 The location of the design throat area should be assumed to be concentrated in the root.
 A uniform distribution of stress is assumed on the throat section of the weld, leading to the normal stresses and shear stresses shown in Figure 4.5, as follows:
 
σ⊥ 
is 
the normal stress perpendicular to the throat 
 
σ∥ 
is 
the normal stress parallel to the axis of the weld 
 
τ⊥ 
is 
the shear stress (in the plane of the throat) perpendicular to the axis of the weld 
 
τ∥ 
is 
the shear stress (in the plane of the throat) parallel to the axis of the weld. 
Figure 4.5: Stresses on the throat section of a fillet weld
 The normal stress σ∥ parallel to the axis is not considered when verifying the design resistance of the weld.
 The design resistance of the fillet weld will be sufficient if the following are both satisfied:
[σ⊥^{2} + 3 (τ⊥^{2} + τ∥^{2})]^{0,5} ≤ f_{u} / (β_{w} γ_{M2}) and σ⊥ ≤ 0.9 f_{u} / γ_{M2} … (4.1)
where:
f_{u} 
is 
the nominal ultimate tensile strength of the weaker part joined; 
β_{w} 
is 
the appropriate correlation factor taken from Table 4.1. 
 Welds between parts with different material strength grades should be designed using the properties of the material with the lower strength grade.
43
Table 4.1: Correlation factor β_{w} for fillet welds
Standard and steel grade 
Correlation factor β_{w} 
EN 10025 
EN 10210 
EN 10219 
S 235 S 235 W 
S 235 H 
S 235 H 
0,8 
S 275 S 275 N/NL S 275 M/ML 
S 275 H S 275 NH/NLH 
S 275 H S 275 NH/NLH S 275 MH/MLH 
0,85 
S 355 S 355 N/NL S 355 M/ML S 355 W 
S 355 H S 355 NH/NLH 
S 355 H S 355 NH/NLH S 355 MH/MLH 
0,9 
S 420 N/NL S 420 M/ML 

S 420 MH/MLH 
1,0 
S 460 N/NL S 460 M/ML S 460 Q/QL/QL1 
S 460 NH/NLH 
S 460 NH/NLH S 460 MH/MLH 
1,0 
4.5.3.3 Simplified method for design resistance of fillet weld
 Alternatively to 4.5.3.2 the design resistance of a fillet weld may be assumed to be adequate if, at every point along its length, the resultant of all the forces per unit length transmitted by the weld satisfy the following criterion:
F_{w,Ed} ≤ F_{w,Rd} … (4.2)
where:
F_{w,Ed} 
is 
the design value of the weld force per unit length; 
F_{w,Rd} 
is 
the design weld resistance per unit length. 
 Independent of the orientation of the weld throat plane to the applied force, the design resistance per unit length F_{w,Rd} should be determined from:
F_{w,Rd} = f_{vw,d} a … (4.3)
where:
f_{vw,d} 
is 
the design shear strength of the weld. 
 The design shear strength f_{vw,d} of the weld should be determined from:
where:
f_{u} and β_{w} are defined in 4.5.3.2(6).
4.6 Design resistance of fillet welds all round
 The design resistance of a fillet weld all round should be determined using one of the methods given in 4.5.
44
4.7 Design resistance of butt welds
4.7.1 Full penetration butt welds
 The design resistance of a full penetration butt weld should be taken as equal to the design resistance of the weaker of the parts connected, provided that the weld is made with a suitable consumable which will produce allweld tensile specimens having both a minimum yield strength and a minimum tensile strength not less than those specified for the parent metal.
4.7.2 Partial penetration butt welds
 The design resistance of a partial penetration butt weld should be determined using the method for a deep penetration fillet weld given in 4.5.2(3).
 The throat thickness of a partial penetration butt weld should not be greater than the depth of penetration that can be consistently achieved, see 4.5.2(3).
4.7.3 Tbutt joints
 The design resistance of a Tbutt joint, consisting of a pair of partial penetration butt welds reinforced by superimposed fillet welds, may be determined as for a full penetration butt weld (see 4.7.1) if the total nominal throat thickness, exclusive of the unwelded gap, is not less than the thickness t of the part forming the stem of the tee joint, provided that the unwelded gap is not more than (t / 5) or 3 mm, whichever is less, see Figure 4.6 .
 The design resistance of a Tbutt joint which does not meet the requirements given in 4.7.3(1) should be determined using the method for a fillet weld or a deep penetration fillet weld given in 4.5 depending on the amount of penetration. The throat thickness should be determined in conformity with the provisions for fillet welds (see 4.5.2) or partial penetration butt welds (see 4.7.2) as relevant.
Figure 4.6: Effective full penetration of Tbutt welds
4.8 Design resistance of plug welds
 The design resistance F_{w,Rd} of a plug weld (see 4.3.3) should be taken as:
F_{w,Rd} = f_{vw,d} A_{w}, … (4.5)
where
f_{vw,d} 
is 
the design shear strength of a weld given in 4.5.3.3(3); 
A_{w} 
is 
the design throat area and should be taken as the area of the hole. 
45
4.9 Distribution of forces
 The distribution of forces in a welded connection may be calculated on the assumption of either elastic or plastic behaviour in conformity with 2.4 and 2.5.
 It is acceptable to assume a simplified load distribution within the welds.
 Residual stresses and stresses not subjected to transfer of load need not be included when checking the resistance of a weld. This applies specifically to the normal stress parallel to the axis of a weld.
 Welded joints should be designed to have adequate deformation capacity. However, ductility of the welds should not be relied upon.
 In joints where plastic hinges may form, the welds should be designed to provide at least the same design resistance as the weakest of the connected parts.
 In other joints where deformation capacity for joint rotation is required due to the possibility of excessive straining, the welds require sufficient strength not to rupture before general yielding in the adjacent parent material.
 If the design resistance of an intermittent weld is determined by using the total length ℓ_{tot}, the weld shear force per unit length F_{w,Ed} should be multiplied by the factor (e+ℓ)/ℓ, see Figure 4.7.
Figure 4.7: Calculation of weld forces for intermittent welds
4.10 Connections to unstiffened flanges
 Where a transverse plate (or beam flange) is welded to a supporting unstiffened flange of an I, H or other section, see Figure 4.8, and provided that the condition given in 4.10(3) is met, the applied force perpendicular to the unstiffened flange should not exceed any of the relevant design resistances as follows:
  that of the web of the supporting member of I or H sections as given in 6.2.6.2 or 6.2.6.3 as appropriate;
  those for a transverse plate on a RHS member as given in Table 7.13;
  that of the supporting flange as given by formula (6.20) in 6.2.6.4.3(1) calculated assuming the applied force is concentrated over an effective width, b_{eff}, of the flange as given in 4.10(2) or 4.10(4) as relevant.
46
Figure 4.8: Effective width of an unstiffened Tjoint
 For an unstiffened I or H section the effective width b_{eff} should be obtained from:
b_{eff} = t_{w} + 2s + 7kt_{f} … (4.6a)
where:
k = (t_{f} / t_{p})(f_{y,f} / f_{y,p}) but k ≤ 1 … (4.6b)
f_{y,f} 
is 
the yield strength of the flange of the I or H section; 
f_{y,p} 
is 
the yield strength of the plate welded to the 1 or H section. 
The dimension s should be obtained from:
  for a rolled I or H section: s = r … (4.6c)
  for a welded I or H section:
 For an unstiffened flange of an I or H section, the following criterion should be satisfied:
b_{eff} ≥ (f_{y,p} / f_{u,p}) b_{p} … (4.7)
where:
f_{u,p} 
is 
the ultimate strength of the plate welded to the I or H section; 
b_{p} 
is 
the width of the plate welded to the I or H section. 
Otherwise the joint should be stiffened.
 For other sections such as box sections or channel sections where the width of the connected plate is similar to the width of the flange, the effective width b_{eff} should be obtained from:
b_{eff} = 2t_{w} + 5t_{f} but b_{eff} ≤ 2t_{w} + 5 k t_{f} … (4.8)
NOTE: For hollow sections, see Table 7.13.
 Even if b_{eff} ≤ b_{p}, the welds connecting the plate to the flange need to be designed to transmit the design resistance of the plate b_{P} t_{P} f_{y,P} / γ_{M0} assuming a uniform stress distribution.
47
4.11 Long joints
 In lap joints the design resistance of a fillet weld should be reduced by multiplying it by a reduction factor β_{Lw} to allow for the effects of nonuniform distribution of stress along its length.
 The provisions given in 4.11 do not apply when the stress distribution along the weld corresponds to the stress distribution in the adjacent base metal, as, for example, in the case of a weld connecting the flange and the web of a plate girder.
 In lap joints longer than 150a the reduction factor β_{Lw} should be taken as β_{Lw.1} given by:
β_{Lw.1} = 1,2 – 0,2L_{j} /(150a) but β_{Lw.1} ≤ 1,0 … (4.9)
where:
L_{j} is the overall length of the lap in the direction of the force transfer.
 For fillet welds longer than 1,7 metres connecting transverse stiffeners in plated members, the reduction factor β_{Lw} may be taken as β_{Lw.2} given by:
β_{Lw.2} = 1,1 – L_{w} / 17 but β_{Lw.2} ≤ 1,0 and β_{Lw.2} ≥ 0,6 … (4.10)
where
L_{w} is the length of the weld (in metres).
4.12 Eccentrically loaded single fillet or singlesided partial penetration butt welds
 Local eccentricity should be avoided whenever it is possible.
 Local eccentricity (relative to the line of action of the force to be resisted) should be taken into account in the following cases:
  Where a bending moment transmitted about the longitudinal axis of the weld produces tension at the root of the weld, see Figure 4.9(a);
  Where a tensile force transmitted perpendicular to the longitudinal axis of the weld produces a bending moment, resulting in a tension force at the root of the weld, see Figure 4.9(b).
 Local eccentricity need not be taken into account if a weld is used as part of a weld group around the perimeter of a structural hollow section.
Figure 4.9: Single fillet welds and singlesided partial penetration butt welds
4.13 Angles connected by one leg
 In angles connected by one leg, the eccentricity of welded lap joint end connections may be allowed for by adopting an effective crosssectional area and then treating the member as concentrically loaded.
 For an equalleg angle, or an unequalleg angle connected by its larger leg, the effective area may be taken as equal to the gross area.
48
 For an unequalleg angle connected by its smaller leg, the effective area should be taken as equal to the gross crosssectional area of an equivalent equalleg angle of leg size equal to that of the smaller leg, when determining the design resistance of the crosssection, see EN 199311. However when determining the design buckling resistance of a compression member, see EN 199311, the actual gross crosssectional area should be used.
4.14 Welding in coldformed zones
 Welding may be carried out within a length 5t either side of a coldformed zone, see Table 4.2, provided that one of the following conditions is fulfilled:
  the coldformed zones are normalized after coldforming but before welding;
  the r/tratio satisfy the relevant value obtained from Table 4.2.
Table 4.2: Conditions for welding coldformed zones and adjacent material
r/t 
Strain due to cold forming (%) 
Maximum thickness (mm) 
Generally 
Fully killed Aluminiumkilled steel (Al ≥ 0,02 %) 
Predominantly static loading 
Where fatigue predominates 
≥ 25 
≤ 2 
any 
any 
any 
≥ 10 
≤ 5 
any 
16 
any 
≥ 3,0 
≤ 14 
24 
12 
24 
≥ 2,0 
≤ 20 
12 
10 
12 
≥ 1,5 
≤ 25 
8 
8 
10 
≥ 1,0 
≤ 33 
4 
4 
6 

NOTE Cold formed hollow sections according to EN 10.219 which do not satisfy the limits given in Table 4.2 can be assumed to satisfy these limits if these sections have a thickness not exceeding 12,5 mm and are Alkilled with a quality J2H, K2H, MH, MLH, NH or NLH and further satisfy C ≤ 0,18%, P ≤ 0,020% and S ≤ 0,012%.
In other cases welding is only permitted within a distance of 5t from the comers if it can be shown by tests that welding is permitted for that particular application.

49
5 Analysis, classification and modelling
5.1 Global analysis
5.1.1 General
 The effects of the behaviour of the joints on the distribution of internal forces and moments within a structure, and on the overall deformations of the structure, should generally be taken into account, but where these effects are sufficiently small they may be neglected.
 To identify whether the effects of joint behaviour on the analysis need be taken into account, a distinction may be made between three simplified joint models as follows:
  simple, in which the joint may be assumed not to transmit bending moments;
  continuous, in which the behaviour of the joint may be assumed to have no effect on the analysis;
  semicontinuous, in which the behaviour of the joint needs to be taken into account in the analysis.
 The appropriate type of joint model should be determined from Table 5.1, depending on the classification of the joint and on the chosen method of analysis.
 The design momentrotation characteristic of a joint used in the analysis may be simplified by adopting any appropriate curve, including a linearized approximation (e.g. bilinear or trilinear), provided that the approximate curve lies wholly below the design momentrotation characteristic.
Table 5.1: Type of joint model
Method of global analysis 
Classification of joint 
Elastic 
Nominally pinned 
Rigid 
Semirigid 
RigidPlastic 
Nominally pinned 
Fullstrength 
Partialstrength 
ElasticPlastic 
Nominally pinned 
Rigid and fullstrength 
Semirigid and partialstrength Semirigid and fullstrength Rigid and partialstrength 
Type of joint model 
Simple 
Continuous 
Semicontinuous 
5.1.2 Elastic global analysis
 The joints should be classified according to their rotational stiffness, see 5.2.2.
 The joints should have sufficient strength to transmit the forces and moments acting at the joints resulting from the analysis.
 In the case of a semirigid joint, the rotational stiffness S_{j} corresponding to the bending moment M_{j,Ed} should generally be used in the analysis. If M_{j,Ed} does not exceed 2/3 M_{j,Rd} the initial rotational stiffness S_{j,ini} may be taken in the global analysis, see Figure 5.1(a).
 As a simplification to 5.1.2(3), the rotational stiffness may be taken as S_{j,ini}/η in the analysis, for all values of the moment M_{j,Ed}, as shown in Figure 5.1(b), where η is the stiffness modification coefficient from Table 5.2.
 For joints connecting H or I sections S_{j} is given in 6.3.1.
50
Figure 5.1: Rotational stiffness to be used in elastic global analysis
Table 5.2: Stiffness modification coefficient η
Type of connection 
Beamtocolumn joints 
Other types of joints (beamtobeam joints, beam splices, column base joints) 
Welded 
2 
3 
Bolted endplates 
2 
3 
Bolted flange cleats 
2 
3,5 
Base plates 
 
3 
5.1.3 Rigidplastic global analysis
 The joints should be classified according to their strength, see 5.2.3.
 For joints connecting H or I sections M_{j,Rd} is given in 6.2.
 For joints connecting hollow sections the method given in section 7 may be used.
 The rotation capacity of a joint should be sufficient to accommodate the rotations resulting from the analysis.
 For joints connecting H or I sections the rotation capacity should be checked according to 6.4.
5.1.4 Elastic plastic global analysis
 The joints should be classified according to both stiffness (see 5.2.2) and strength (see 5.2.3).
 For joints connecting H or I sections M_{j,Rd} is given in 6.2, S_{j} is given in 6.3.1 and ϕ_{Cd} is given in 6.4.
 For joints connecting hollow sections the method given in section 7 may be used.
 The moment rotation characteristic of the joints should be used to determine the distribution of internal forces and moments.
 As a simplification, the bilinear design momentrotation characteristic shown in Figure 5.2 may be adopted. The stiffness modification coefficient η should be obtained from Table 5.2.
51
Figure 5.2: Simplified bilinear design momentrotation characteristic
5.1.5 Global analysis of lattice girders
 The provisions given in 5.1.5 apply only to structures whose joints are verified according to section 7.
 The distribution of axial forces in a lattice girder may be determined on the assumption that the members are connected by pinned joints (see also 2.7).
 Secondary moments at the joints, caused by the rotational stiffnesses of the joints, may be neglected both in the design of the members and in the design of the joints, provided that both of the following conditions are satisfied:
  the joint geometry is within the range of validity specified in Table 7.1, Table 7.8, Table 7.9 or Table 7.20 as appropriate;
  the ratio of the system length to the depth of the member in the plane of the lattice girder is not less than the appropriate minimum value. For building structures, the appropriate minimum value may be assumed to be 6. Larger values may apply in other parts of EN 1993;
  the eccentricity is within the limits specified in 5.1.5(5).
 The moments resulting from transverse loads (whether inplane or outofplane) that are applied between panel points, should be taken into account in the design of the members to which they are applied. Provided that the conditions given in 5.1.5(3) are satisfied:
  the brace members may be considered as pinconnected to the chords, so moments resulting from transverse loads applied to chord members need not be distributed into brace members, and vice versa;
  the chords may be considered as continuous beams, with simple supports at panel points.
 Moments resulting from eccentricities may be neglected in the design of tension chord members and brace members. They may also be neglected in the design of connections if the eccentricities are within the following limits:
  −0,55 d_{0} ≤ e ≤ 0,25 d_{0} … (5.1a)
  −0,55 h_{0} ≤ e ≤ 0,25 h_{0} … (5.1b)
where:
e 
is 
the eccentricity defined in Figure 5.3; 
d_{0} 
is 
the diameter of the chord; 
h_{0} 
is 
the depth of the chord, in the plane of the lattice girder. 
 When the eccentricities are within the limits given in 5.1.5(5), the moments resulting from the eccentricities should be taken into account in the design of compression chord members. In this case the moments produced by the eccentricity should be distributed between the compression chord 52 members on each side of the joint, on the basis of their relative stiffness coefficients I/L , where L is the system length of the member, measured between panel points.
 When the eccentricities are outside the limits given in 5.1.5(5), the moments resulting from the eccentricities should be taken into account in the design of the joints and the members . In this case the moments produced by the eccentricity should be distributed between all the members meeting at the joint, on the basis of their relative stiffness coefficients I/L.
 The stresses in a chord resulting from moments taken into account in the design of the chord, should also be taken into account in determining the factors k_{m}, k_{n} and k_{p} used in the design of the joints, see Table 7.2 to Table 7.5, Table 7.10 and Table 7.12 to Table 7.14.
 The cases where moments should be taken into account are summarized in Table 5.3.
Figure 5.3: Eccentricity of joints
Table 5.3 Allowance for bending moments
Type of component 
Source of the bending moment 
Secondary effects 
Transverse loading 
Eccentricity 
Compression chord 
Not if 5.1.5(3) is satisfied 
Yes 
Yes 
Tension chord 
Not if 5.1.5(3) and (5) are satisfied 
Brace member 
Not if 5.1.5(3) and (5) are satisfied 
Joint 
Not if 5.1.5(3) and (5) are satisfied 
53
5.2 Classification of joints
5.2.1 General
 The details of all joints should fulfil the assumptions made in the relevant design method, without adversely affecting any other part of the structure.
 Joints may be classified by their stiffness (see 5.2.2) and by their strength (see 5.2.3).
NOTE: The National Annex may give additional information on the classification of joints by their stiffness and strength to that given in 5.2.2.1(2).
5.2.2 Classification by stiffness
5.2.2.1 General
 A joint may be classified as rigid, nominally pinned or semirigid according to its rotational stiffness, by comparing its initial rotational stiffness S_{j,ini} with the classification boundaries given in 5.2.2.5.
NOTE: Rules for the determination of S_{j,ini} for joints connecting H or I sections are given in 6.3.1. Rules for the determination of S_{j,ini} for joints connecting hollow sections are not given in this Standard.
 A joint may be classified on the basis of experimental evidence, experience of previous satisfactory performance in similar cases or by calculations based on test evidence.
5.2.2.2 Nominally pinned joints
 A nominally pinned joint should be capable of transmitting the internal forces, without developing significant moments which might adversely affect the members or the structure as a whole.
 A nominally pinned joint should be capable of accepting the resulting rotations under the design loads.
5.2.2.3 Rigid joints
 Joints classified as rigid may be assumed to have sufficient rotational stiffness to justify analysis based on full continuity.
5.2.2.4 Semirigid joints
 A joint which does not meet the criteria for a rigid joint or a nominally pinned joint should be classified as a semirigid joint.
NOTE: Semirigid joints provide a predictable degree of interaction between members, based on the design momentrotation characteristics of the joints.
 Semirigid joints should be capable of transmitting the internal forces and moments.
5.2.2.5 Classification boundaries
 Classification boundaries for joints other than column bases are given in 5.2.2.1(1) and Figure 5.4.
54
Figure 5.4: Classification of joints by stiffness
 Column bases may be classified as rigid provided the following conditions are satisfied:
5.2.3 Classification by strength
5.2.3.1 General
 A joint may be classified as fullstrength, nominally pinned or partial strength by comparing its design moment resistance M_{j,Rd} with the design moment resistances of the members that it connects. When classifying joints, the design resistance of a member should be taken as that member adjacent to the joint.
5.2.3.2 Nominally pinned joints
 A nominally pinned joint should be capable of transmitting the internal forces, without developing significant moments which might adversely affect the members or the structure as a whole.
55
 A nominally pinned joint should be capable of accepting the resulting rotations under the design loads.
 A joint may be classified as nominally pinned if its design moment resistance M_{j,Rd} is not greater than 0,25 times the design moment resistance required for a fullstrength joint, provided that it also has sufficient rotation capacity.
5.2.3.3 Fullstrength joints
 The design resistance of a full strength joint should be not less than that of the connected members.
 A joint may be classified as fullstrength if it meets the criteria given in Figure 5.5.
Figure 5.5: Fullstrength joints
5.2.3.4 Partialstrength joints
 A joint which does not meet the criteria for a fullstrength joint or a nominally pinned joint should be classified as a partialstrength joint.
5.3 Modelling of beamtocolumn joints
 To model the deformational behaviour of a joint, account should be taken of the shear deformation of the web panel and the rotational deformation of the connections.
 Joint configurations should be designed to resist the internal bending moments M_{b1,Ed} and M_{b2,Ed}, normal forces N_{b1,Ed} and N_{b2,Ed} and shear forces V_{b1,Ed} and V_{b2,Ed} applied to the joints by the connected members, see Figure 5.6.
 The resulting shear force V_{wp,Ed} in the web panel should be obtained using:
V_{wp,Ed} = (M_{b1,Ed} – M_{b2,Ed})/ z – (V_{c1,Ed} – V_{c2,Ed})/2 … (5.3)
where:
z is the lever arm, see 6.2.7.
 To model a joint in a way that closely reproduces the expected behaviour, the web panel in shear and each of the connections should be modelled separately, taking account of the internal moments and forces in the members, acting at the periphery of the web panel, see Figure 5.6(a) and Figure 5.7.
 As a simplified alternative to 5.3(4), a singlesided joint configuration may be modelled as a single joint, and a doublesided joint configuration may be modelled as two separate but interacting joints, one on each side. As a consequence a doublesided beamtocolumn joint configuration has two momentrotation characteristics, one for the righthand joint and another for the lefthand joint.
56
 In a doublesided, beamtocolumn joint each joint should be modelled as a separate rotational spring, as shown in Figure 5.8, in which each spring has a momentrotation characteristic that takes into account the behaviour of the web panel in shear as well as the influence of the relevant connections.
 When determining the design moment resistance and rotational stiffness for each of the joints, the possible influence of the web panel in shear should be taken into account by means of the transformation parameters β_{1} and β_{2}, where:
β_{1} 
is 
the value of the transformation parameter β for the righthand side joint; 
β_{2} 
is 
the value of the transformation parameter β for the lefthand side joint. 
NOTE: The transformation parameters β_{1} and β_{2} are used directly in 6.2.7.2(7) and 6.3.2(1). They are also used in 6.2.6.2(1) and 6.2.6.3(4) in connection with Table 6.3 to obtain the reduction factor ω for shear.
 Approximate values for β_{1} and β_{2} based on the values of the beam moments M_{b1,Ed} and M_{b2,Ed} at the periphery of the web panel, see Figure 5.6(a), may be obtained from Table 5.4.
Figure 5.6: Forces and moments acting on the joint
Figure 5.7: Forces and moments acting on the web panel at the connections
57
Figure 5.8: Modelling the joint
 As an alternative to 5.3(8), more accurate values of β_{1} and β_{2} based on the values of the beam moments M_{j,b1,Ed} and M_{j,b2,Ed} at the intersection of the member centrelines, may be determined from the simplified model shown in Figure 5.6(b) as follows:
where:
M_{j,b1,Ed} 
is 
the moment at the intersection from the right hand beam; 
M_{j,b2,Ed} 
is 
the moment at the intersection from the left hand beam. 
 In the case of an unstiffened doublesided beamtocolumn joint configuration in which the depths of the two beams are not equal, the actual distribution of shear stresses in the column web panel should be taken into account when determining the design moment resistance.
58
Table 5.4: Approximate values for the transformation parameter β
Type of joint configuration 
Action 
Value of β 

M_{b1,Ed} 
β ≈ 1 

M_{b1,Ed} = M_{b2,Ed} 
β = 0 *) 
M_{b1,Ed} / M_{b2,Ed} > 0 
β ≈ 1 
M_{b1,Ed} / M_{b2,Ed} < 0 
β ≈ 2 
M_{b1,Ed} + M_{b2,Ed} = 0 
β ≈ 2 
*) In this case the value of β is the exact value rather than an approximation. 
59
6 Structural joints connecting H or I sections
6.1 General
6.1.1 Basis
 This section contains design methods to determine the structural properties of joints in frames of any type. To apply these methods, a joint should be modelled as an assembly of basic components, see 1.4(1).
 The basic components used in this Standard are identified in Table 6.1 and their properties should be determined in accordance with the provisions given in this Standard. Other basic components may be used provided their properties are based on tests or analytical and numerical methods supported by tests, see EN 1990.
NOTE: The design methods for basic joint components given in this Standard are of general application and can also be applied to similar components in other joint configurations. However the specific design methods given for determining the design moment resistance, rotational stiffness and rotation capacity of a joint are based on an assumed distribution of internal forces for joint configurations indicated in Figure 1.2. For other joint configurations, design methods for determining the design moment resistance, rotational stiffness and rotation capacity should be based on appropriate assumptions for the distribution of internal forces.
6.1.2 Structural properties
6.1.2.1 Design momentrotation characteristic
 A joint may be represented by a rotational spring connecting the centre lines of the connected members at the point of intersection, as indicated in Figure 6.1(a) and (b) for a singlesided beamtocolumn joint configuration. The properties of the spring can be expressed in the form of a design momentrotation characteristic that describes the relationship between the bending moment M_{j,Ed} applied to a joint and the corresponding rotation ϕ_{Ed} between the connected members. Generally the design momentrotation characteristic is nonlinear as indicated in Figure 6.1(c).
 A design momentrotation characteristic, see Figure 6.1(c) should define the following three main structural properties:
  moment resistance;
  rotational stiffness;
  rotation capacity.
NOTE: In certain cases the actual momentrotation behaviour of a joint includes some rotation due to such effects as bolt slip, lack of fit and, in the case of column bases, foundationsoil interactions. This can result in a significant amount of initial hinge rotation that may need to be included in the design momentrotation characteristic.
 The design momentrotation characteristics of a beamtocolumn joint should be consistent with the assumptions made in the global analysis of the structure and with the assumptions made in the design of the members, see EN 199311.
 The design momentrotation characteristic for joints and column bases of I and H sections as obtained from 6.3.1(4) may be assumed to satisfy the requirements of 5.1.1(4) for simplifying this characteristic for global analysis purposes.
60
6.1.2.2 Design Moment resistance
 The design moment resistance M_{j,Rd}, which is equal to the maximum moment of the design momentrotation characteristic, see Figure 6.1(c), should be taken as that given by 6.1.3(4)
6.1.2.3 Rotational stiffness
 The rotational stiffness S_{j}, which is the secant stiffness as indicated in Figure 6.1(c), should be taken as that given by 6.3.1(4). For a design momentrotation characteristic this definition of S_{j} applies up to the rotation ϕ_{Xd} at which M_{j,Ed} first reaches M_{j,Rd}, but not for larger rotations, see Figure 6.1(c). The initial rotational stiffness S_{j,ini}, which is the slope of the elastic range of the design momentrotation characteristic, should be taken as that given by 6.1.3(4).
6.1.2.4 Rotation capacity
 The design rotation capacity ϕ_{Cd} of a joint, which is equal to the maximum rotation of the design momentrotation characteristic, see Figure 6.1(c), should be taken as that given by 6.1.3(4).
Figure 6.1: Design momentrotation characteristic for a joint
6.1.3 Basic components of a joint
 The design momentrotation characteristic of a joint should depend on the properties of its basic components, which should be among those identified in 6.1.3(2).
 The basic joint components should be those identified in Table 6.1, together with the reference to the application rules which should be used for the evaluation of their structural properties.
 Certain joint components may be reinforced. Details of the different methods of reinforcement are given in 6.2.4.3 and 6.2.6.
 The relationships between the properties of the basic components of a joint and the structural properties of the joint should be those given in the following clauses:
  for moment resistance in 6.2.7 and 6.2.8;
  for rotational stiffness in 6.3.1;
  for rotation capacity in 6.4.
61
Table 6.1: Basic joint components
Component 
Reference to application rules 
Design Resistance 
Stiffness coefficient 
Rotation capacity 
1 
Column web panel in shear 

6.2.6.1 
6.3.2 
6.4.2 and 6.4.3 
2 
Column web In transverse compression 

6.2.6.2 
6.3.2 
6.4.2 and 6.4.3 
3 
Column web in transverse tension 

6.2.6.3 
6.3.2 
6.4.2 and 6.4.3 
4 
Column flange in bending 

6.2.6.4 
6.3.2 
6.4.2 and 6.4.3 
5 
Endplate in bending 

6.2.6.5 
6.3.2 
6.4.2 
6 
Flange cleat in bending 

6.2.6.6 
6.3.2 
6.4.2 62 
7 
Beam or column flange and web in compression 

6.2.6.7 
6.3.2 
*) 
8 
Beam web in tension 

6.2.6.8 
6.3.2 
*) 
9 
Plate in tension or compression 

in tension  EN 199311 in compression:  EN 199311 
6.3.2 
*) 
10 
Bolts in tension 

With column flange:  6.2.6.4 with endplate:  6.2.6.5 with flange cleat:  6.2.6.6 
6.3.2 
6.4.2 
11 
Bolts in shear 

3.6 
6.3.2 
6.4.2 
12 
Bolts in bearing (on beam flange, column flange, endplate or cleat) 

3.6 
6.3.2 
*) 63 
13 
Concrete in compression including grout 

6.2.6.9 
6.3.2 
*) 
14 
Base plate in bending under compression 

6.2.6.10 
6.3.2 
*) 
15 
Base plate in bending under tension 

6.2.6.11 
6.3.2 
*) 
16 
Anchor bolts in tension 

6.2.6.12 
6.3.2 
*) 
17 
Anchor bolts in shear 

6.2.2 
*) 
*) 
18 
Anchor bolts in bearing 

6.2.2 
*) 
*) 
19 
Welds 

4 
6.3.2 
*) 
20 
Haunched beam 

6.2.6.7 
6.3.2 
*) 
*) No information available in this part. 
64
6.2 Design Resistance
6.2.1 Internal forces
 The stresses due to the internal forces and moments in a member may be assumed not to affect the design resistances of the basic components of a joint, except as specified in 6.2.1(2) and 6.2.1(3).
 The longitudinal stress in a column should be taken into account when determining the design resistance of the column web in compression, see 6.2.6.2(2).
 The shear in a column web panel should be taken into account when determining the design resistance of the following basic components:
  column web in transverse compression, see 6.2.6.2;
  column web in transverse tension, see 6.2.6.3.
6.2.2 Shear forces
 In welded connections, and in bolted connections with endplates, the welds connecting the beam web should be designed to transfer the shear force from the connected beam to the joint, without any assistance from the welds connecting the beam flanges.
 In bolted connections with endplates, the design resistance of each boltrow to combined shear and tension should be verified using the criterion given in Table 3.4, taking into account the total tensile force in the bolt, including any force due to prying action.
NOTE: As a simplification, bolts required to resist in tension may be assumed to provide their full design resistance in tension when it can be shown that the design shear force does not exceed the sum of:
 the total design shear resistance of those bolts that are not required to resist tension and;
 (0,4/1,4) times the total design shear resistance of those bolts that are also required to resist tension.
 In bolted connections with angle flange cleats, the cleat connecting the compression flange of the beam may be assumed to transfer the shear force in the beam to the column, provided that:
  The gap g between the end of the beam and the face of the column does not exceed the thickness t_{a} of the angle cleat;
  the force does not exceed the design shear resistance of the bolts connecting the cleat to the column;
  the web of the beam satisfies the requirement given in EN 199315, section 6.
 The design shear resistance of a joint may be derived from the distribution of internal forces within that joint, and the design resistances of its basic components to these forces, see Table 6.1.
 In base plates if no special elements for resisting shear are provided, such as block or bar shear connectors, it should be demonstrated that the design friction resistance of the base plate, see 6.2.2(6), and, in cases where the bolt holes are not oversized, the design shear resistance of the anchor bolts, see 6.2.2(7), added up is sufficient to transfer the design shear force. The design bearing resistance of the block or bar shear connectors with respect to the concrete should be checked according to EN 1992.
 In a column base the design friction resistance F_{f,Rd} between base plate and grout should be derived as follows:
F_{f,Rd} = C_{f,d} N_{c,Ed} … (6.1)
where:
65
C_{f,d} 
is 
the coefficient of friction between base plate and grout layer. The following values may be used:
  for sandcement mortar C_{f,d} = 0,20;
  for other types of grout the coefficient of friction C_{f,d} should be determined by testing in accordance with EN 1990, Annex D;

N_{c,Ed} 
is 
is the design value of the normal compressive force in the column. 
NOTE: If the column is loaded by a tensile normal force, F_{f,Rd} = 0.
 In a column base the design shear resistance of an anchor bolt F_{vb,Rd} should be taken as the smaller of F_{1,vb,Rd} and F_{2,vb,Rd} where:
  F_{1,vb,Rd} is the shear resistance of the anchor bolt, see 3.6.1
 
where:
α_{b} 
= 
0,44  0,0003 f_{yb} 
f_{yb} 
is 
the yield strength of the anchor bolt, where 235 N/mm^{2} ≤ f_{yb} ≤ 640 N/mm^{2} 
 The design shear resistance F_{v,Rd} between a column base plate and a grout layer should be derived as follows:
F_{v,Rd} = F_{f,Rd} + n F_{vb,Rd} … (6.3)
where:
n 
is 
the number of anchor bolts in the base plate. 
 The concrete and reinforcement used in the base should be designed in accordance with EN 1992.
6.2.3 Bending moments
 The design moment resistance of any joint may be derived from the distribution of internal forces within that joint and the design resistances of its basic components to these forces, see Table 6.1.
 Provided that the axial force N_{Ed} in the connected member does not exceed 5% of the design resistance N_{pℓ,Rd} of its crosssection, the design moment resistance M_{j,Rd} of a beamto column joint or beam splice may be determined using the method given in 6.2.7.
 The design moment resistance M_{j,Rd} of a column base may be determined using the method given in 6.2.8.
 In all joints, the sizes of the welds should be such that the design moment resistance of the joint M_{j,Rd} is always limited by the design resistance of its other basic components, and not by the design resistance of the welds.
 In a beamtocolumn joint or beam splice in which a plastic hinge is required to form and rotate under any relevant load case, the welds should be designed to resist the effects of a moment at least equal to the smaller of:
  the design plastic moment resistance of the connected member M_{pℓ,Rd}
  α a times the design moment resistance of the joint M_{j,Rd}
where:
α = 1,4 
 for frames in which the bracing system satisfies the criterion (5.1) in EN 199311 clause 5.2.1(3) with respect to sway; 
α = 1,7 
 for all other cases. 
66
 In a bolted connection with more than one boltrow in tension, as a simplification the contribution of any boltrow may be neglected, provided that the contributions of all other boltrows closer to the centre of compression are also neglected.
6.2.4 Equivalent Tstub in tension
6.2.4.1 General
 In bolted connections an equivalent Tstub in tension may be used to model the design resistance of the following basic components:
  column flange in bending;
  endplate in bending;
  flange cleat in bending;
  base plate in bending under tension.
 Methods for modelling these basic components as equivalent Tstub flanges, including the values to be used for e_{min}, ℓ_{eff} and m, are given in 6.2.6.
 The possible modes of failure of the flange of an equivalent Tstub may be assumed to be similar to those expected to occur in the basic component that it represents.
 The total effective length ∑ℓ_{eff} of an equivalent Tstub, see Figure 6.2, should be such that the design resistance of its flange is equivalent to that of the basic joint component that it represents.
NOTE: The effective length of an equivalent Tstub is a notional length and does not necessarily correspond to the physical length of the basic joint component that it represents.
 The design tension resistance of a Tstub flange should be determined from Table 6.2.
NOTE: Prying effects are implicitly taken into account when determining the design tension resistance according to Table 6.2.
 In cases where prying forces may develop, see Table 6.2, the design tension resistance of a Tstub flange F_{T,Rd} should be taken as the smallest value for the three possible failure modes 1, 2 and 3.
 In cases where prying forces may not develop the design tension resistance of a Tstub flange F_{T,Rd} should be taken as the smallest value for the two possible failure modes according to Table 6.2.
Figure 6.2: Dimensions of an equivalent Tstub flange
67
Table 6.2: Design Resistance F_{T,Rd} of a Tstub flange

Prying forces may develop, i.e. L_{b} ≤ L_{b}* 
No prying forces 
Mode 1 
Method 1 
Method 2 (alternative method) 

without backing plates 


with backing plates 


Mode 2 

Mode 3 
F_{T,3,Rd} = ΣF_{t,Rd} 
Mode 1: Complete yielding of the flange
Mode 2: Bolt failure with yielding of the flange
Mode 3: Bolt failure
L_{b} 
is 
 the bolt elongation length, taken equal to the grip length (total thickness of material and washers), plus half the sum of the height of the bolt head and the height of the nut or 


 the anchor bolt elongation length, taken equal to the sum of 8 times the nominal bolt diameter, the grout layer, the plate thickness, the washer and half the height of the nut 

F_{T,Rd} 
is 
the design tension resistance of a Tstub flange 
Q 
is 
the prying force 
M_{pℓ,1,Rd} 
= 
0,25∑ℓ _{eff,1} t_{f}^{2} f_{y} / γ _{M0} 
M_{pℓ,2,Rd} 
= 
0,25∑ℓ _{eff,2} t_{f}^{2} f_{y} / γ _{M0} 
M_{bp,Rd} 
= 
0,25∑ℓ _{eff,1} t_{bp}^{2} f_{y,bp} / γ _{M0} 
n 
= 
e_{min} but n ≤ 1,25m 
n_{b} 
is 
the number of bolt rows (with 2 bolts per row) 
F_{t,Rd} 
is 
the design tension resistance of a bolt, see Table 3.4; 
∑F_{t,Rd} 
is 
the total value of F_{t,Rd} for all the bolts in the Tstub; 
∑ℓ_{eff,1} 
is 
is the value of ∑ℓ_{eff} for mode 1; 
∑ℓ_{eff,2} 
is 
is the value of ∑ℓ_{eff} for mode 2; 
e_{min}, m and t_{f} are as indicated in figure 6.2. 
f_{y,bp} 
is 
the yield strength of the backing plates; 
t_{bp} 
is 
the thickness of the backing plates; 
e_{w} 

= d_{w} / 4; 
d_{w} 
is 
the diameter of the washer, or the width across points of the bolt head or nut, as relevant. 

NOTE 1: In bolted beamtocolumn joints or beam splices it may be assumed that prying forces will develop.
NOTE 2: In method 2, the force applied to the Tstub flange by a bolt is assumed to be uniformly distributed under the washer, the bolt head or the nut, as appropriate, see figure, instead of concentrated at the centreline of the bolt. This assumption leads to a higher value for mode 1, but leaves the values for F_{T,12,Rd} and modes 2 and 3 unchanged.


68
6.2.4.2 Individual boltrows, boltgroups and groups of boltrows
 Although in an actual Tstub flange the forces at each boltrow are generally equal, when an equivalent Tstub flange is used to model a basic component listed in 6.2.4.1(1), allowance should be made for the different in forces at each boltrow.
 When using the equivalent Tstub approach to model a group of bolt rows it may be necessary to divide the group into separate boltrows and use an equivalent Tstub to model each separate boltrow.
 When using the Tstub approach to model a group of bolt rows the following conditions should be satisfied:
 the force at each boltrow should not exceed the design resistance determined considering only that individual boltrow;
 the total force on each group of boltrows, comprising two or more adjacent boltrows within the same boltgroup, should not exceed the design resistance of that group of boltrows.
 When determining the design tension resistance of a basic component represented by an equivalent Tstub flange, the following parameters should be calculated:
 the design resistance of an individual boltrow, determined considering only that boltrow;
 the contribution of each boltrow to the design resistance of two or more adjacent boltrows within a boltgroup, determined considering only those boltrows.
 In the case of an individual boltrow ∑ℓ_{eff} should be taken as equal to the effective length ℓ_{eff} tabulated in 6.2.6 for that boltrow taken as an individual boltrow.
 (6) In the case of a group of boltrows ∑ℓ_{eff} should be taken as the sum of the effective lengths ℓ_{eff} tabulated in 6.2.6 for each relevant boltrow taken as part of a boltgroup.
6.2.4.3 Backing plates
 Backing plates may be used to reinforce a column flange in bending as indicated in Figure 6.3.
 Each backing plate should extend at least to the edge of the column flange, and to within 3 mm of the toe of the root radius or of the weld.
 The backing plate should extend beyond the furthermost bolt rows active in tension as defined in Figure 6.3.
 Where backing plates are used, the design resistance of the Tstub F_{T,Rd} should be determined using the method given in Table 6.2.
Figure 6.3: Column flange with backing plates
69
6.2.5 Equivalent Tstub in compression
 In steel toconcrete joints, the flange of an equivalent Tstub in compression may be used to model the design resistances for the combination of the following basic components:
  the steel base plate in bending under the bearing pressure on the foundation;
  the concrete and/or grout joint material in bearing.
 The total effective length l_{eff} and the total effective width b_{eff} of an equivalent Tstub should be such that the design compression resistance of the Tstub is equivalent to that of the basic joint component it represents.
NOTE: The values for the effective length and the effective width of an equivalent Tstub are notional values for these lengths and may differ to the physical dimensions of the basic joint component it represents.
 The design compression resistance of a Tstub flange F_{C,Rd} should be determined as follows:
F_{C,Rd} = f_{jd} b_{eff} l_{eff} … (6.4)
where:
b_{eff} 
is 
the effective width of the Tstub flange, see 6.2.5(5) and 6.2.5(6) 
l_{eff} 
is 
the effective length of the Tstub flange, see 6.2.5(5) and 6.2.5(6) 
f _{jd} 
is 
the design bearing strength of the joint, see 6.2.5(7) 
 The forces transferred through a Tstub should be assumed to spread uniformly as shown in Figure 6.4(a) and (b). The pressure on the resulting bearing area should not exceed the design bearing strength f_{jd} and the additional bearing width, c, should not exceed:
c = t [f_{y} / (3 f_{jd} γ_{M0})]^{0.5} … (6.5)
where:
t 
is 
the thickness of the Tstub flange; 
f_{y} 
is 
the yield strength of the Tstub flange. 
 Where the projection of the physical length of the basic joint component represented by the Tstub is less than c, the effective area should be taken as indicated in Figure 6.4(a)
 Where the projection of the physical length of the basic joint component represented by the Tstub exceeds c on any side, the part of the additional projection beyond the width c should be neglected, see Figure 6.4(b).
Figure 6.4: Area of equivalent TStub in compression
70
 The design bearing strength of the joint f_{jd} should be determined from:
f_{jd} = β_{j} F_{Rdu} / (b_{eff} l_{eff}) … (6.6)
where:
β_{j} 
is 
the foundation joint material coefficient, which may be taken as 2/3 provided that the characteristic strength of the grout is not less than 0,2 times the characteristic strength of the concrete foundation and the thickness of the grout is not greater than 0,2 times the smallest width of the steel base plate. In cases where the thickness of the grout is more than 50 mm, the characteristic strength of the grout should be at least the same as that of the concrete foundation. 
F_{Rdu} 
is 
the concentrated design resistance force given in EN 1992, where A_{c0} is to be taken as (b_{eff} l_{eff}).

6.2.6 Design Resistance of basic components
6.2.6.1 Column web panel in shear
 The design methods given in 6.2.6.1(2) to 6.2.6.1(14) are valid provided the column web slenderness satisfies the condition d_{c}/t_{w} ≤ 69ε .
 For a singlesided joint, or for a doublesided joint in which the beam depths are similar, the design plastic shear resistance V_{wp,Rd} of an unstiffened column web panel, subject to a design shear force V_{wp,Ed}, see 5.3(3), should be obtained using:
where:
A_{vc} 
is 
the shear area of the column, see EN 199311. 
 The design shear resistance may be increased by the use of stiffeners or supplementary web plates.
 Where transverse web stiffeners are used in both the compression zone and the tension zone, the design plastic shear resistance of the column web panel V_{wp,Rd} may be increased by V_{wp,add,Rd} given by:
where:
d_{s} 
is 
the distance between the centrelines of the stiffeners; 
M_{pℓ,fc,Rd} 
is 
the design plastic moment resistance of a column flange 
M_{pℓ,st,Rd} 
is 
the design plastic moment resistance of a stiffener. 
NOTE: In welded joints, the transverse stiffeners should be aligned with the corresponding beam flange.
 When diagonal web stiffeners are used the design plastic shear resistance of a column web should be determined according to EN 199311.
NOTE: In doublesided beamtocolumn joint configurations without diagonal stiffeners on the column webs, the two beams are assumed to have similar depths.
 Where a column web is reinforced by adding a supplementary web plate, see Figure 6.5, the shear area A_{vc} may be increased by b_{s} t_{wc}. If a further supplementary web plate is added on the other side of the web, no further increase of the shear area should be made.
71
 Supplementary web plates may also be used to increase the rotational stiffness of a joint by increasing the stiffness of the column web in shear, compression or tension, see 6.3.2(1).
 The steel grade of the supplementary web plate should be equal to that of the column.
 The width b_{s} should be such that the supplementary web plate extends at least to the toe of the root radius or of the weld.
 The length ℓ_{s} should be such that the supplementary web plate extends throughout the effective width of the web in tension and compression, see Figure 6.5.
 The thickness t_{s} of the supplementary web plate should be not less than the column web thickness t_{wc}.
 The welds between the supplementary web plate and profile should be designed to resist the applied design forces.
 The width b_{s} of a supplementary web plate should be less than 40ε t_{s}.
 Discontinuous welds may be used in non corrosive environments.
Figure 6.5: Examples of supplementary web plates
6.2.6.2 Column web in transverse compression
 The design resistance of an unstiffened column web subject to transverse compression should be determined from:
72
where:
ω 
is 
a reduction factor to allow for the possible effects of interaction with shear in the column web panel according to Table 6.3; 
b_{eff,c,wc} 
is 
the effective width of column web in compression: 
 
for a welded connection:


a_{c}, r_{c} and a_{b} are as indicated in Figure 6.6 
 
for bolted endplate connection:


s_{p} is the length obtained by dispersion at 45° through the endplate (at least t_{p} and, provided that the length of endplate below the flange is sufficient, up to 2t_{p}). 
 
for bolted connection with angle flange cleats: b_{eff,c,wc} = 2t_{a} + 0,6r_{a} + 5 (t_{fc} + s) 
… (6.12) 

 
for a rolled I or H section column: 
s = r_{c} 


 
for a welded I or H section column: 


ρ 
is 
the reduction factor for plate buckling: 
 
if ≤ 0,72: 
ρ = 1,0 
… (6.13a) 
 
if > 0,72: 

… (6.13b) 

is 
the plate slenderness:

 
for a rolled I or H section column: 
d_{wc} = h_{c} – 2(t_{fc} + r_{c}) 
 
for a welded I or H section column: 

k_{wc} 
is 
a reduction factor and is given in 6.2.6.2(2). 
Table 6.3: Reduction factor ω for interaction with shear
Transformation parameter β 
Reduction factor ω 
0 ≤ β ≤ 0,5 
ω = 1 
0,5 < β < 1 
ω = ω_{1} + 2(1 – β) (1 – ω_{1}) 
β = 1 
ω = ω_{1} 
1 < β < 2 
ω = ω_{1} + (β – 1) (ω_{2} – ω_{1}) 
β = 2 
ω = ω_{2} 


A_{vc} 
is 
the shear area of the column, see 6.2.6.1; 
β 
is 
the transformation parameter, see 5.3(7). 

73
 Where the maximum longitudinal compressive stress σ_{com,Ed} due to axial force and bending moment in the column exceeds 0,7f_{y,wc} in the web (adjacent to the root radius for a rolled section or the toe of the weld for a welded section), its effect on the design resistance of the column web in compression should be allowed for by multiplying the value of F_{c,wc,Rd} given by expression (6.9) by a reduction factor k_{wc} as follows:
  when σ_{com,Ed} ≤ 0,7 f_{y,wc} : k_{wc} = 1
  when σ_{com,Ed} > 0,7 f_{y,wc} : k_{wc} = 1,7 – σ_{com,Ed} / f_{y,wc} … (6.14)
NOTE: Generally the reduction factor k_{wc} is 1,0 and no reduction is necessary. It can therefore be omitted in preliminary calculations when the longitudinal stress is unknown and checked later.
Figure 6.6: Transverse compression on an unstiffened column
 The ‘columnsway’ buckling mode of an unstiffened column web in compression illustrated in Figure 6.7 should normally be prevented by constructional restraints.
Figure 6.7: ‘Columnsway’ buckling mode of an unstiffened web
 Stiffeners or supplementary web plates may be used to increase the design resistance of a column web in transverse compression.
74
 Transverse stiffeners or appropriate arrangements of diagonal stiffeners may be used (in association with or as an alternative to transverse stiffeners) in order to increase the design resistance of the column web in compression.
NOTE: In welded joints, the transverse stiffeners should be aligned with the corresponding beam flange. In bolted joints, the stiffener in the compression zone should be aligned with the centre of compression as defined Figure 6.15.
 Where an unstiffened column web is reinforced by adding a supplementary web plate conforming with 6.2.6.1, the effective thickness of the web may be taken as 1,5 t_{wc} if one supplementary web plate is added, or 2,0 t_{wc} if supplementary web plates are added to both sides of the web. In calculating the reduction factor ω for the possible effects of shear stress, the shear area A_{vc} of the web may be increased only to the extent permitted when determining its design shear resistance, see 6.2.6.1(6).
6.2.6.3 Column web in transverse tension
 The design resistance of an unstiffened column web subject to transverse tension should be determined from:
where:
ω 
is 
a reduction factor to allow for the interaction with shear in the column web panel. 
 For a welded connection, the effective width b_{eff,t,wc} of a column web in tension should be obtained using:
where:
 
for a rolled I or H section column: 
s = r_{c} 
 
for a welded I or H section column: 

where:
a_{c} and r are as indicated in Figure 6.8 and a_{b} is as indicated in Figure 6.6.
 For a bolted connection, the effective width b_{eff,t,wc} of column web in tension should be taken as equal to the effective length of equivalent Tstub representing the column flange, see 6.2.6.4.
 The reduction factor ω to allow for the possible effects of shear in the column web panel should be determined from Table 6.3, using the value of b_{eff,t,wc} given in 6.2.6.3(2) or 6.2.6.3(3) as appropriate.
 Stiffeners or supplementary web plates may be used to increase the design tension resistance of a column web.
 Transverse stiffeners and/or appropriate arrangements of diagonal stiffeners may be used to increase the design resistance of the column web in tension.
NOTE: In welded joints, the transverse stiffeners are normally aligned with the corresponding beam flange.
75
 The welds connecting diagonal stiffeners to the column flange should be fillin welds with a sealing run providing a combined throat thickness equal to the thickness of the stiffeners.
 Where an unstiffened column web is reinforced by adding supplementary web plates conforming with 6.2.6.1, the design tension resistance depends on the throat thickness of the longitudinal welds connecting the supplementary web plates. The effective thickness of the web t_{w,eff} should be taken as follows:
  when (he longitudinal welds are full penetration butt welds with a throat thickness a ≥ t_{s} then:
 
for one supplementary web plate: 
t_{w,eff} = l,5 t_{wc} 
… (6.17) 
 
for supplementary web plates both sides: 
t_{w,eff} = 2,0 t_{wc} 
… (6.18) 
  when the longitudinal welds are fillet welds with a throat thickness then for either one or two supplementary web plates:
 
for steel grades S 235, S 275 or S 355: 
t_{w,eff} = 1,4 t_{wc} 
… (6.19a) 
 
for steel grades S 420 or S 460: 
t_{w,eff} = 1,3 t_{wc} 
… (6.19b) 
 In calculating the reduction factor ω for the possible effects of shear stress, the shear area A_{vc} of a column web reinforced by adding supplementary web plates may be increased only to the extent permitted when determining its design shear resistance, see 6.2.6.1(6).
6.2.6.4 Column flange in tranverse bending
6.2.6.4.1 Unstiffened column flange, bolted connection
 The design resistance and failure mode of an unstiffened column flange in tranverse bending, together with the associated bolts in tension, should be taken as similar to those of an equivalent Tstub flange, see 6.2.4, for both:
  each individual boltrow required to resist tension;
  each group of boltrows required to resist tension.
 The dimensions e_{min} and m for use in 6.2.4 should be determined from Figure 6.8.
 The effective length of equivalent Tstub flange should be determined for the individual boltrows and the boltgroup in accordance with 6.2.4.2 from the values given for each boltrow in Table 6.4.
76
Figure 6.8: Definitions of e, e_{min}, r_{c} and m
Table 6.4: Effective lengths for an unstiffened column flange
Boltrow Location 
Boltrow considered individually 
Boltrow considered as part of a group of boltrows 
Circular patterns ℓ_{eff,cp} 
Non ℓ_{eff,nc} 
Circular patterns ℓ_{eff,cp} 
Noncircular patterns ℓ_{eff,nc} 
Inner boltrow 
2πm 
4m + l,25e 
2p 
p 
End boltrow 
The smaller of: 2πm πm + 2e_{1} 
The smaller of: 4m + l,25e 2m + 0,625e + e_{1} 
The smaller of: πm + p 2e_{1} + p 
The smaller of: 2m + 0,625e + 0,5p e_{1} + 0,5p 
Mode 1: 
ℓ_{eff,1} = ℓ_{eff,nc} but ℓ_{eff,1} ≤ ℓ_{eff,cp} 
Σℓ_{eff,1} = Σℓ_{eff,nc} but Σℓ_{eff,1} ≤ Σℓ_{eff,cp} 
Mode 2: 
ℓ_{eff,2} = ℓ_{eff,nc} 
Σℓ_{eff,2} = Σℓ_{eff,nc} 
e_{1} is the distance from the centre of the fasteners in the end row to the adjacent free end of the column flange measured in the direction of the axis of the column profile (see row 1 and row 2 in Figure 6.9). 
77
6.2.6.4.2 Stiffened column flange, joint with bolted endplate or flange cleats
 Transverse stiffeners and/or appropriate arrangements of diagonal stiffeners may be used to increase the design resistance of the column flange in bending.
 The design resistance and failure mode of a stiffened column flange in transverse bending, together with the associated bolls in tension, should be taken as similar to those of an equivalent Tstub flange, see 6.2.4, for both:
  each individual boltrow required to resist tension;
  each group of boltrows required to resist tension.
 The groups of boltrows on either side of a stiffener should be modelled as separate equivalent Tstub flanges, see Figure 6.9. The design resistance and failure mode should be determined separately for each equivalent Tstub.
Figure 6.9: Modelling a stiffened column flange as separate Tstubs
 The dimensions e_{min} and m for use in 6.2.4 should be determined from Figure 6.8.
 The effective lengths of an equivalent Tstub flange ℓ_{eff} should be determined in accordance with 6.2.4.2 using the values for each boltrow given in Table 6.5. The value of a for use in Table 6.5 should be obtained from Figure 6.11.
 The stiffeners should meet the requirements specified in 6.2.6.1.
78
Table 6.5: Effective lengths for a stiffened column flange
Boltrow Location 
Boltrow considered individually 
Boltrow considered as part of a group of boltrows 
Circular patterns ℓ_{eff,cp} 
Noncircular patterns ℓ_{eff,nc} 
Circular patterns ℓ_{eff,cp} 
Noncircular patterns ℓ_{eff,nc} 
Boltrow adjacent to a stiffener 
2πm 
αm 
πm + p 
0,5p + αm − (2m + 0,625e) 
Other inner boltrow 
2πm 
4m + l,25e 
2p 
p 
Other end boltrow 
The smaller of: 2πm πm + 2e_{1} 
The smaller of: 4m + l,25e 2m + 0,625e + e_{1} 
The smaller of: πm + p 2e_{1} + p 
The smaller of: 2m + 0,625e + 0,5p e_{1} + 0,5p 
End boltrow adjacent to a stiffener 
The smaller of: 2πm πm + 2e_{1} 
e_{1} + αm − (2m + 0,625e) 
not relevant 
not relevant 
For Mode 1: 
ℓ_{eff,1} = ℓ_{eff,nc} but ℓ_{eff,1} ≤ ℓ_{eff,cp} 
Σℓ_{eff,1} = Σℓ_{eff,nc} but Σℓ_{eff,1} ≤ Σℓ_{eff,cp} 
For Mode 2: 
ℓ_{eff,2} = ℓ_{eff,nc} 
Σℓ_{eff,2} = Σℓ_{eff,nc} 
α should be obtained from Figure 6.11. e_{1} is the distance from the centre of the fasteners in the end row to the adjacent stiffener of the column flange measured in the direction of the axis of the column profile (see row 1 and row 4 in Figure 6.9). 
6.2.6.4.3 Unstiffened column flange, welded connection
 In a welded joint, the design resistance F_{fc,Rd} of an unstiffened column flange in bending, due to tension or compression from a beam flange, should be obtained using:
F_{fc,Rd} = b_{eff,b,fc} t _{fb} f _{γ,fb} / γ _{M0} … (6.20)
where:
b_{eff,b,fc} is the effective breath b_{eff} defined in 4.10 where the beam flange is considered as a plate.
NOTE: See also the requirements specified in 4.10 .
6.2.6.5 Endplate in bending
 The design resistance and failure mode of an endplate in bending, together with the associated bolts in tension, should be taken as similar to those of an equivalent Tstub flange, see 6.2.4 for both:
  each individual boltrow required to resist tension;
  each group of boltrows required to resist tension.
 The groups of boltrows either side of any stiffener connected to the endplate should be treated as separate equivalent Tstubs. In extended endplates, the boltrow in the extended part should also be treated as a separate equivalent Tstub, see Figure 6.10. The design resistance and failure mode should be determined separately for each equivalent Tstub.
 The dimension e_{min} required for use in 6.2.4 should be obtained from Figure 6.8 for that part of the endplate located between the beam flanges. For the endplate extension e_{min} should be taken as equal to e_{x}, see Figure 6.10.
 The effective length of an equivalent Tstub flange ℓ_{eff} should be determined in accordance with 6.2.4.2 using the values for each boltrow given in Table 6.6.
79
 The values of m and m_{x} for use in Table 6.6 should be obtained from Figure 6.10.
Figure 6.10: Modelling an extended endplate as separate Tstubs
Table 6.6: Effective lengths for an endplate
Boltrow Location 
Boltrow considered individually 
Boltrow considered as part of a group of boltrows 
Circular patterns ℓ_{eff,cp} 
Noncircular patterns ℓ_{eff,nc} 
Circular patterns ℓ_{eff,cp} 
Noncircular patterns ℓ_{eff,nc} 
Boltrow outside tension flange of beam 
Smallest of: 2πm_{x} πm_{x} + w πm_{x} + 2e 
Smallest of: 4m_{x} + 1,25e_{x} e+2m_{x}+0,625e_{x} 0,5b_{p} 0,5w+2m_{x}+0,625e_{x} 
— 
— 
First boltrow below tension flange of beam 
2πm 
αm 
πm + p 
0,5p + αm − (2m + 0,625e) 
Other inner boltrow 
2πm 
4m + l,25e 
2p 
p 
Other end boltrow 
2πm 
4m + l,25e 
πm + p 
2m+0,625e+0,5p 
Mode 1: 
ℓ_{eff,1} = ℓ_{eff,nc} but ℓ_{eff,1} ≤ ℓ_{eff,cp} 
Σℓ_{eff,1} = Σℓ_{eff,nc} but Σℓ_{eff,1} ≤ Σℓ_{eff,cp} 
Mode 2: 
ℓ_{eff,2} = ℓ_{eff,nc} 
Σℓ_{eff,2} = Σℓ_{eff,nc} 
α should be obtained from Figure 6.11. 
80
Figure 6.11: Values of α for stiffened column flanges and endplates
6.2.6.6 Flange cleat in bending
 The design resistance and failure mode of a bolted angle flange cleat in bending, together with the associated bolts in tension, should be taken as similar to those of an equivalent Tstub flange, see 6.2.4.
 The effective length ℓ_{eff} of the equivalent Tstub flange should be taken as 0,5b_{a} where b_{a} is the length of the angle cleat, see Figure 6.12.
81
 The dimensions e_{min} and m for use in 6.2.4 should be determined from Figure 6.13.
Figure 6.12: Effective length ℓ_{eff} of an angle flange cleat
Figure 6.13: Dimensions e_{min} and m for a bolted angle cleat
6.2.6.7 Beam flange and web in compression
 The resultant of the design compression resistance of a beam flange and the adjacent compression zone of the beam web, may be assumed to act at the level of the centre of compression, see 6.2.7. The design compression resistance of the combined beam flange and web is given by the following expression:
F_{c,fb,Rd} = M_{c,Rd}/(h − t_{fb}) … (6.21)
where:
h 
is the depth of the connected beam; 
M_{c,Rd} 
is the design moment resistance of the beam crosssection, reduced if necessary to allow for shear, see EN 199311. For a haunched beam M_{c,Rd} may be calculated neglecting the intermediate flange. 
t_{fb} 
is the flange thickness of the connected beam. 
82
If the height of the beam including the haunch exceeds 600 mm the contribution of the beam web to the design compression resistance should be limited to 20%.
 If a beam is reinforced with haunches they should be arranged such that:
  the steel grade of the haunch should match that of the member;
  the flange size and the web thickness of the haunch should not be less than that of the member;
  the angle of the haunch flange to the flange of the member should not be greater than 45°;
  the length of stiff bearing s_{s} should be taken as equal to the thickness of the haunch flange parallel to the beam.
 If a beam is reinforced with haunches, the design resistance of beam web in compression should be determined according to 6.2.6.2.
6.2.6.8 Beam web in tension
 In a bolted endplate connection, the design tension resistance of the beam web should be obtained from:
F_{t,wb,Rd} = b_{eff,t,wb} t_{wb} f_{y,wb} / γ _{M0} … (6.22)
 The effective width b_{eff,t,wb} of the beam web in tension should be taken as equal to the effective length of the equivalent Tstub representing the endplate in bending, obtained from 6.2.6.5 for an individual boltrow or a boltgroup.
6.2.6.9 Concrete in compression including grout
 The design bearing strength of the joint between the base plate and its concrete support should be determined taking account of the material properties and dimensions of both the grout and the concrete support. The concrete support should be designed according to EN 1992.
 The design resistance of concrete in compression, including grout, together with the associated base plate in bending F_{c,pl,Rd}, should be taken as similar to those of an equivalent Tstub, see 6.2.5.
6.2.6.10 Base plate in bending under compression
 The design resistance of a base plate in bending under compression, together with concrete slab on which the column base is placed F_{c,pl,Rd}, should be taken as similar to those of an equivalent Tstub, see 6.2.5.
6.2.6.11 Base plate in bending under tension
 The design resistance and failure mode of a base plate in bending under tension, together with the associated anchor bolts in tension F_{t,pl,Rd}, may be determined using the rules given in 6.2.6.5.
 In the case of base plates prying forces which may develop should not be taken into consideration when determining the thickness of the base plate. Prying forces should be taken into account when determining the anchor bolts.
6.2.6.12 Anchor bolt in tension
 Anchor bolts should be designed to resist the effects of the design loads. They should provide design resistance to tension due to uplift forces and bending moments where appropriate.
 When calculating the tension forces in the anchor bolts due to bending moments, the lever arm should not be taken as more than the distance between the centroid of the bearing area on the compression side and the centroid of the bolt group on the tension side.
NOTE: Tolerances on the positions of the anchor bolts may have an influence.
83
 The design resistance of the anchor bolts should be taken as the smaller of the design tension resistance of the anchor bolt, see 3.6, and the design bond resistance of the concrete on the anchor bolt according to EN 199211.
 One of the following methods should be used to secure anchor bolts into the foundation:
  a hook (Figure 6.14(a)),
  a washer plate (Figure 6.14(b)),
  some other appropriate load distributing member embedded in the concrete,
  some other fixing which has been adequately tested and approved.
 When the bolts are provided with a hook, the anchorage length should be such as to prevent bond failure before yielding of the bolt. The anchorage length should be calculated in accordance with EN 199211. This type of anchorage should not be used for bolts with a yield strength f_{yb} higher than 300 N/mm^{2}.
 When the anchor bolts are provided with a washer plate or other load distributing member, no account should be taken of the contribution of bond. The whole of the force should be transferred through the load distributing device.
Figure 6.14: Fixing of anchor bolts
6.2.7 Design moment resistance of beamtocolumn joints and splices
6.2.7.1 General
 The applied design moment M_{j,Ed} should satisfy:
84
 The methods given in 6.2.7 for determining the design moment resistance of a joint M_{j,Rd} do not take account of any coexisting axial force N_{Ed} in the connected member. They should not be used if the axial force in the connected member exceeds 5% of the design plastic resistance N_{pℓ,Rd} of its crosssection.
 If the axial force N_{Ed} in the connected beam exceeds 5% of the design resistance, N_{pl,Rd}, the following conservative method may be used:
where:
M_{j,Rd} 
is 
the design moment resistance of the joint, assuming no axial force; 
N_{j,Rd} 
is 
the axial design resistance of the joint, assuming no applied moment. 
 The design moment resistance of a welded joint should be determined as indicated in Figure 6.15(a).
 The design moment resistance of a bolted joint with a flush endplate that has only one boltrow in tension (or in which only one boltrow in tension is considered, see 6.2.3(6)) should be determined as indicated in Figure 6.15(c).
 The design moment resistance of a bolted joint with angle flange cleats should be determined as indicated in Figure 6.15(b).
 The design moment resistance of a bolted endplate joint with more than one row of bolts in tension should generally be determined as specified in 6.2.7.2.
 As a conservative simplification, the design moment resistance of an extended endplate joint with only two rows of bolts in tension may be approximated as indicated in Figure 6.16, provided that the total design resistance F_{Rd} does not exceed 3,8F_{t,Rd}, where F_{t,Rd} is given in Table 6.2. In this case the whole tension region of the endplate may be treated as a single basic component. Provided that the two boltrows are approximately equidistant either side of the beam flange, this part of the endplate may be treated as a Tstub to determine the boltrow force F_{1,Rd}. The value of F_{2,Rd} may then be assumed to be equal to F_{1,Rd}, and so F_{Rd} may be taken as equal to 2F_{1,Rd}.
 The centre of compression should be taken as the centre of the stress block of the compression forces. As a simplification the centre of compression may be taken as given in Figure 6.15.
 A splice in a member or part subject to tension should be designed to transmit all the moments and forces to which the member or part is subjected at that point.
 Splices should be designed to hold the connected members in place. Friction forces between contact surfaces may not be relied upon to hold connected members in place in a bearing splice.
 Wherever practicable the members should be arranged so that the centroidal axis of any splice material coincides with the centroidal axis of the member. If eccentricity is present then the resulting forces should be taken into account.
85
Type of connection 
Centre of compression 
Lever arm 
Force distributions 
a) Welded connection

In line with the mid thickness of the compression flange 
z = h  t_{fb}
h 
is the depth of the connected beam 
t_{fb} 
is the thickness of the beam flange 


b) Bolted connection with angle flange cleats

In line with the midthickness of the leg of the angle cleat on the compression flange 
Distance from the centre of compression to the boltrow in tension 

c) Bolted endplate connection with only one boltrow active in tension

In line with the midthickness of the compression flange 
Distance from the centre of compression to the boltrow in tension 

d) Bolted extended endplate connection with only two boltrows active in tension

In line with the midthickness of the compression flange 
Conservatively z may be taken as the distance from the centre of compression to a point midway between these two boltrows 

e) Other bolted endplate connections with two or more boltrows in tension

In line with the midthickness of the compression flange 
An approximate value may be obtained by taking the distance from the centre of compression to a point midway between the farthest two boltrows in tension 
A more accurate value may be determined by taking the lever arm z as equal to z_{eq} obtained using the method given in 6.3.3.1. 
Figure 6.15: Centre of compression, lever arm z and force distributions for deriving the design moment resistance M_{j,Rd}
86
Figure 6.16: Simplified models for bolted joints with extended endplates
 Where the members are not prepared for full contact in bearing, splice material should be provided to transmit the internal forces and moments in the member at the spliced section, including the moments due to applied eccentricity, initial imperfections and secondorder deformations. The internal forces and moments should be taken as not less than a moment equal to 25% of the moment capacity of the weaker section about both axes and a shear force equal to 2.5% of the normal force capacity of the weaker section in the directions of both axes.
 Where the members are prepared for full contact in bearing, splice material should be provided to transmit at least 25% of the maximum compressive force in the column.
 The alignment of the abutting ends of members subjected to compression should be maintained by cover plates or other means. The splice material and its fastenings should be proportioned to carry forces at the abutting ends, acting in any direction perpendicular to the axis of the member. In the design of splices the second order effects should also be taken into account.
 Splices in flexural members should comply with the following:
 Compression flanges should be treated as compression members;
 Tension flanges should be treated as tension members;
 Parts subjected to shear should be designed to transmit the following effects acting together:
  the shear force at the splice;
  the moment resulting from the eccentricity, if any, of the centroids of the groups of fasteners on each side of the splice;
  the proportion of moment, deformation or rotations carried by the web or part, irrespective of any shedding of stresses into adjoining parts assumed in the design of the member or part.
6.2.7.2 Beamtocolumn joints with bolted endplate connections
 The design moment resistance of M_{j,Rd} beamtocolumn joint with a bolted endplate connection may be determined from:
where:
F_{tr,Rd} 
is 
the effective design tension resistance of boltrow r ; 
h_{r} 
is 
the distance from boltrow r to the centre of compression; 
r 
is 
the boltrow number. 
87
NOTE: In a bolted joint with more than one boltrow in tension, the boltrows are numbered starting from the boltrow farthest from the centre of compression.
 For bolted endplate connections, the centre of compression should be assumed to be in line with the centre of the compression flange of the connected member.
 The effective design tension resistance F_{tr,Rd} for each boltrow should be determined in sequence, starting from boltrow 1, the boltrow farthest from the centre of compression, then progressing to boltrow 2, etc.
 When determining the effective design tensin resistance F_{tr,Rd} for boltrow r the effective design tension resistance of all other boltrows closer to the centre of compression should be ignored.
 The effective design tension resistance F_{tr,Rd} of boltrow r should be taken as its design tension resistance F_{t,Rd} as an individual boltrow determined from 6.2.7.2(6), reduced if necessary to satisfy the conditions specified in 6.2.7.2(7), (8) and (9).
 The effective design tension resistance F_{tr,Rd} of boltrow r, taken as an individual boltrow, should be taken as the smallest value of the design tension resistance for an individual boltrow of the following basic components:
 
the column web in tension 
F_{t,wc,Rd} 
 
see 6.2.6.3; 
 
the column flange in bending 
F_{t,fc,Rd} 
 
see 6.2.6.4; 
 
the endplate in bending 
F_{t,cp,Rd} 
 
see 6.2.6.5; 
 
the beam web in tension 
F_{t,wb,Rd} 
 
see 6.2.6.8. 
 The effective design tension resistance F_{tr,Rd} of boltrow r should, if necessary, be reduced below the value of F_{t,Rd} text deleted to ensure that, when account is taken of all boltrows up to and including boltrow r the following conditions are satisfied:
 
the total design resistance ΣF_{t,Rd} ≤ V_{wp,Rd}/β  with β from 5.3(7) 
 
see 6.2.6.1; 
 
the total design resistance ΣF_{t,Rd} does not exceed the smaller of: 

 
the design resistance of the column web in compression F_{c,wc,Rd} 
 
see 6.2.6.2; 

 
the design resistance of the beam flange and web in compression F_{c,fb,Rd} 
 
see 6.2.6.7. 
 The effective design tension resistance F_{tr,Rd} of boltrow r should, if necessary, be reduced below the value of F_{t,Rd} text deleted , to ensure that the sum of the design resistances taken for the boltrows up to and including boltrow r that form part of the same group of boltrows, does not exceed the design resistance of that group as a whole. This should be checked for the following basic components:
 
the column web in tension 
F_{t,wc,Rd} 
 
see 6.2.6.3; 
 
the column flange in bending 
F_{t,fc,Rd} 
 
see 6.2.6.4; 
 
the endplate in bending 
F_{t,ep,Rd} 
 
see 6.2.6.5; 
 
the beam web in tension 
F_{t,wb,Rd} 
 
see 6.2.6.8. 
 Where the effective design tension resistance F_{tx,Rd} of one of the previous boltrows x is greater than 1,9F_{t,Rd}, then the effective design tension resistance F_{tr,Rd} for boltrow r should be reduced, if necessary, in order to ensure that:
F_{tr,Rd} ≤ F_{tx,Rd} h_{r}/h_{x} … (6.26)
where:
h_{x} 
is 
the distance from boltrow x to the centre of compression; 88 
x 
is 
the boltrow farthest from the centre of compression that has a design tension resistance greater than 1,9F_{t,Rd}. 
NOTE: The National Annex may give further information on the use of equation (6.26).
 The method described in 6.2.7.2(1) to 6.2.7.2(9) may be applied to a bolted beam splice with welded endplates, see Figure 6.17, by omitting the items relating to the column.
Figure 6.17: Bolted beam splices with welded endplates
6.2.8 Design resistance of column bases with base plates
6.2.8.1 General
 Column bases should be of sufficient size, stiffness and strength to transmit the axial forces, bending moments and shear forces in columns to their foundations or other supports without exceeding the load carrying capacity of these supports.
 The design bearing strength between the base plate and its support may be determined on the basis of a uniform distribution of compressive force over the bearing area. For concrete foundations the bearing stress should not exceed the design bearing strength, f_{jd}, given in 6.2.5(7).
 For a column base subject to combined axial force and bending the forces between the base plate and its support can take one of the following distribution depending on the relative magnitude of the applied axial force and bending moment:
  In the case of a dominant compressive axial force, full compression may develop under both column flanges as shown in Figure 6.18(a).
  In the case of a dominant tensile force, full tension may develop under both flanges as shown in Figure 6.18(b).
  In the case of a dominant bending moment compression may develop under one column flange and tension under the other as shown in Figure 6.18(c) and Figure 6.18(d).
 Base plates should be designed using the appropriate methods given in 6.2.8.2 and 6.2.8.3.
 One of the following methods should be used to resist the shear force between the base plate and its support:
  Frictional design resistance at the joint between the base plate and its support added up with the design shear resistance of the anchor bolts.
  The design shear resistance of the surrounding part of the foundation.
If anchor bolts are used to resist the shear forces between the base plate and its support, rupture of the concrete in bearing should also be checked, according to EN 1992.
89
Where the above methods are inadequate special elements such as blocks or bar shear connectors should be used to transfer the shear forces between the base plate and its support.
Figure 6.18: Determination of the lever arm z for column base connections
6.2.8.2 Column bases only subjected to axial forces
 The design resistance, N_{j,Rd}, of a symmetric column base plate subject to an axial compressive force applied concentrically may be determined by adding together the individual design resistance F_{C,Rd} of the three Tstubs shown in Figure 6.19 (Two Tstubs under the column flanges and one Tstub under the column web.) The three Tstubs should not be overlapping, see Figure 6.19. The design resistance of each of these Tstubs should be calculated using the method given in 6.2.5.
Figure 6.19: Non overlapping Tstubs
6.2.8.3 Column bases subjected to axial forces and bending moments
 The design moment resistance M_{j,Rd} of a column base subject to combined axial force and moment should be determined using the method given in Table 6.7 where the contribution of the concrete portion just under the column web (Tstub 2 of Figure 6.19) to the compressive capacity is omitted. The following parameters are used in this method:
 
F_{T,l,Rd} 
is the design tension resistance of the left hand side of the joint 
 
see 6.2.8.3(2) 
 
F_{T,r,Rd} 
is the design tension resistance of the right hand side of the joint 
 
see 6.2.8.3(3) 
 
F_{C,l,Rd} 
is the design compressive resistance of the left hand side of the joint 
 
see 6.2.8.3(4) 
 
F_{C,r,Rd} 
is the design compressive resistance of the right hand side of the joint 
 
see 6.2.8.3(5) 
90
 The design tension resistance F_{T,l,Rd} of the left side of the joint should be taken as the smallest values of the design resistance of following basic components:
 
the column web in tension under the left column flange 
F_{t,wc,Rd} 
 
see 6.2.6.3; 
 
the base plate in bending under the left column flange 
F_{t,pl,Rd} 
 
see 6.2.6.11. 
 The design tension resistance F_{T,r,Rd} of the right side of the joint should be taken as the smallest values of the design resistance of following basic components:
 
the column web in tension under the right column flange 
F_{t,wc,Rd} 
 
see 6.2.6.3; 
 
the base plate in bending under the right column flange 
F_{t,pl,Rd} 
 
see 6.2.6.11. 
 The design compressive resistance F_{C,l,Rd} of the left side of the joint should be taken as the smallest values of the design resistance of following basic components:
 
the concrete in compression under the left column flange 
F_{c,pl,Rd} 
 
see 6.2.6.9; 
 
the left column flange and web in compression 
F_{c,fc,Rd} 
 
see 6.2.6.7. 
 The design compressive resistance F_{C,r,Rd} of the right side of the joint should be taken as the smallest values of the design resistance of following basic components:
 
the concrete in compression under the right column flange 
F_{c,pl,Rd} 
 
see 6.2.6.9; 
 
the right column flange and web in compression 
F_{c,fc,Rd} 
 
see 6.2.6.7. 
 For the calculation of z_{T,l}, z_{C,l}, z_{T,r}, z_{C,r} see 6.2.8.1.
Table 6.7: Design moment resistance M_{j,Rd} of column bases
Loading 
Lever arm z 
Design moment resistance M_{j,Rd} 
Left side in tension Right side in compression 
z = z_{T,l} + z_{C,r} 
N_{Ed} > 0 and e > z_{T,l} 
N_{Ed} ≤ 0 and e ≤ z_{C,r} 
The smaller of 
Left side in tension Right side in tension 
z = z_{T,l} + z_{T,r} 
N_{Ed} > 0 and 0 < e < z_{T,l} 
N_{Ed} > 0 and z_{T,r} < e ≤ 0 
The smaller of 
The smaller of 
Left side in compression Right side in tension 
z = z_{C,l} + z_{T,r} 
N_{Ed} > 0 and e ≤ −z_{T,r} 
N_{Ed} ≤ 0 and e > z_{C,l} 
The smaller of 
Left side in compression Right side in compression 
z = z_{C,l} + z_{C,r} 
N_{Ed} ≤ 0 and 0 < e < z_{C,l} 
N_{Ed} ≤ 0 and −z_{C,r} < e ≤ 0 
The smaller of 
The smaller of 
M_{Ed} > 0 is clockwise, N_{Ed} > 0 is tension

91
6.3 Rotational stiffness
6.3.1 Basic model
 The rotational stiffness of a joint should be determined from the flexibilities of its basic components, each represented by an elastic stiffness coefficient k_{i} obtained from 6.3.2.
NOTE: These elastic stiffness coefficients are for general application.
 For a bolted endplate joint with more than one row of bolts in tension, the stiffness coefficients k_{i} for the related basic components should be combined. For beamtocolumn joints and beam splices a method is given in 6.3.3 and for column bases a method is given in 6.3.4.
 In a bolted end plate joint with more than one boltrow in tension, as a simplification the contribution of any boltrow may be neglected, provided that the contributions of all other boltrows closer to the centre of compression are also neglected. The number of boltrows retained need not necessarily be the same as for the determination of the design moment resistance.
 Provided that the axial force N_{Ed} in the connected member does not exceed 5% of the design resistance N_{pℓ,Rd} of its crosssection, the rotational stiffness S_{j} of a beamtocolumn joint or beam splice, for a moment M_{j,Ed} less than the design moment resistance M_{j,Rd} of the joint, may be obtained with sufficient accuracy from:
where:
k_{i} 
is 
the stiffness coefficient for basic joint component i; 
z 
is 
the lever arm, see 6.2.7; 
μ 
is 
the stiffness ratio S_{j,ini}/S_{j}, see 6.3.1(6). 
NOTE: The initial rotational stiffness S_{j,ini} of the joint is given by expression (6.27) with μ = 1,0.
 The rotational stiffness S_{j} of a column base, for a moment M_{j,Ed} less than the design moment resistance M_{j,Rd} of the joint, may be obtained with sufficient accuracy from 6.3.4.
 The stiffness ratio μ should be determined from the following:
in which the coefficient ψ is obtained from Table 6.8.
92
Table 6.8: Value of the coefficient ψ
Type of connection 
ψ 
Welded 
2,7 
Bolted endplate 
2,7 
Bolted angle flange cleats 
3,1 
Base plate connections 
2,7 
 The basic components that should be taken into account when calculating the stiffness of a welded beamtocolumn joint and a joint with bolted angle flange cleats are given in Table 6.9. Similarly, the basic components for a bolted endplate connection and a base plate are given in Table 6.10. In both of these tables the stiffness coefficients, k_{i} ,for the basic components are defined in Table 6.11.
 For beamtocolumn end plate joints the following procedure should be used for obtaining the joint stiffness. The equivalent stiffness coefficient, k_{eq}, and the equivalent lever arm, z_{eq}, of the joint should be obtained from 6.3.3. The stiffness of the joint should then be obtained from 6.3.1(4) based on the stiffness coefficients, k_{eq} (for the joint), k_{1} (for the column web in shear), and with the lever arm, z, taken equal to the equivalent lever arm of the joint, z_{eq}.
Table 6.9: Joints with welded connections or bolted angle flange cleat connections
Beamtocolumn joint with welded connections 
Stiffness coefficients k_{i} to be taken into account 
Singlesided 
k_{1}; k_{2}; k_{3} 
Doublesided – Moments equal and opposite 
k_{2}; k_{3} 
Doublesided – Moments unequal 
k_{1}; k_{2}; k_{3} 
Beamtocolumn joint with Bolted angle flange cleat connections 
Stiffness coefficients k_{i} to be taken into account 
Singlesided 
k_{1}; k_{2}; k_{3}; k_{4}; k_{6}; k_{10}; k_{11} *); k_{12} **) 
Doublesided – Moments equal and opposite 
k_{2}; k_{3}; k_{4}; k_{6}; k_{10}; k_{11} *); k_{12} **) 
Doublesided – Moments unequal 
k_{1}; k_{2}; k_{4}; k_{6}; k_{10}; k_{11} *); k_{12} **) 

*) Two k_{11} coefficients, one for each flange;
**) Four k_{12} coefficients, one for each flange and one for each cleat.

93
Table 6.10: Joints with bolted endplate connections and base plate connections
Beamtocolumn joint with bolted endplate connections 
Number of boltrows in tension 
Stiffness coefficients k_{i} to be taken into account 
Singlesided 
One 
k_{1}; k_{2}; k_{3}; k_{4}; k_{5}; k_{10} 
Two or more 
k_{1}; k_{2}; k_{eq} 
Double sided – Moments equal and opposite 
One 
k_{2}; k_{3}; k_{4}; k_{5}; k_{10} 
Two or more 
k_{2}; k_{eq} 
Double sided – Moments unequal 
One 
k_{1}; k_{2}; k_{3}; k_{4}; k_{5}; k_{10} 
Two or more 
k_{1}; k_{2}; k_{eq} 
Beam splice with bolted endplates 
Number of boltrows in tension 
Stiffness coefficients k_{i} to be taken into account 
Double sided  Moments equal and opposite 
One 
k_{5} [left]; k_{5} [right]; k_{10} 
Two or more 
k_{eq} 
Base plate connections 
Number of boltrows in tension 
Stiffness coefficients k_{i} to be taken into account 
Base plate connections 
One 
k_{13}; k_{15}; k_{16} 
Two or more 
k_{13}; k_{15} and k_{16} for each bolt row 
6.3.2 Stiffness coefficients for basic joint components
 The stiffness coefficients for basic joint component should be determined using the expressions given in Table 6.11.
94
Table 6.11: Stiffness coefficients for basic joint components
Component 
Stiffness coefficient k_{i} 
Column web panel in shear 
Unstiffened, singlesided joint, or a doublesided joint in which the beam depths are similar 
stiffened 

k_{1} = ∞ 
z 
is 
the lever arm from Figure 6.15; 
β 
is 
the transformation parameter from 5.3(7). 

Column web in compression 
unstiffened 
stiffened 

k_{2} = ∞ 
b_{eff,c,wc} 
is the effective width from 6.2.6.2 

Column web in tension 
stiffened or unstiffened bolted connection with a single boltrow in tension or unstiffened welded connection 
stiffened welded connection 

k_{3} = ∞ 
b_{eff,t,wc} 
is the effective width of the column web in tension from 6.2.6.3. For a joint with a single boltrow in tension, b_{eff,t,wc} should be taken as equal to the smallest of the effective lengths ℓ_{eff} (individually or as part of a group of boltrows) given for this boltrow in Table 6.4 (for an unstiffened column flange) or Table 6.5 (for a stiffened column flange). 

Column flange in bending (for a single boltrow in tension) 
ℓ_{eff} 
is the smallest of the effective lengths (individually or as part of a bolt group) for this boltrow given in Table 6.4 for an unstiffened column flange or Table 6.5 for a stiffened column flange; 
m 
is as defined in Figure 6.8. 

Endplate in bending (for a single boltrow in tension) 
ℓ_{eff} 
is the smallest of the effective lengths (individually or as part of a group of boltrows) given for this boltrow in Table 6.6; 
m 
is generally as defined in Figure 6.11, but for a boltrow located in the extended part of an extended endplate m = m_{x}, where m_{x} is as defined in Figure 6.10. 

Flange cleat in bending 
ℓ_{eff} 
is the effective length of the flange cleat from Figure 6.12; 
m 
is as defined in Figure 6.13. 
95 
Bolts in tension (for a single boltrow) 
k_{10} = 1,6 A_{s} / L_{b} preloaded or nonpreloaded
L_{b} 
is the bolt elongation length, taken as equal to the grip length (total thickness of material and washers), plus half the sum of the height of the bolt head and the height of the nut. 

Bolts in shear 
nonpreloaded 
preloaded *) 

k_{11} = ∞ 
d_{M16} 
is the nominal diameter of an M16 bolt; 
n_{b} 
is the number of boltrows in shear. 

Bolts in bearing (for each component j on which the bolts bear) 
nonpreloaded 
preloaded *) 

k_{12} = ∞ 
k_{b} = k_{b1} but k_{b} ≤ k_{b2} k_{b1} = 0,25 e_{b} / d + 0,5 but k_{b1} ≤ 1,25 k_{b2} = 0,25 p_{b} / d + 0,375 but k_{b2} ≤ 1,25 k_{t} = 1,5 t_{j} / d_{M16} but k_{t} ≤ 2,5 
e_{b} 
is the distance from the boltrow to the free edge of the plate in the direction of load transfer; 
f_{u} 
is the ultimate tensile strength of the steel on which the bolt bears; 
p_{b} 
is the spacing of the boltrows in the direction of load transfer; 
t_{j} 
is the thickness of that component. 

Concrete in compression (including grout) 
b_{eff} 
is the effective width of the Tstub flange, see 6.2.5(3); 
l_{eff} 
is the effective length of the Tstub flange, see 6.2.5(3). 

Plate in bending under compression 
k_{14} = ∞
This coefficient is already taken into consideration in the calculation of the stiffness coefficient k_{13}

Base plate in bending under tension (for a single bolt row in tension) 
with prying forces **) 
without prying forces **) 


l_{eff} 
is the effective length of the Tstub flange, see 6.2.5(3); 
t_{p} 
is the thickness of the base plate; 
m 
is the distance according to Figure 6.8. 

Anchor bolts in tension 
with prying forces **) 
without prying forces **) 
k_{16} = 1,6 A_{s} / L_{b} 
k_{16} = 2,0 A_{s} / L_{b} 
L_{b} 
is the anchor bolt elongation length, taken as equal to the sum of 8 times the nominal bolt diameter, the grout layer, the plate thickness, the washer and half of the height of the nut. 

*) 
provided that the bolts have been designed not to slip into bearing at the load level concerned 
**) 
prying forces may develop, if 
96 
NOTE 1: When calculating b_{eff} and l_{eff} the distance c should be taken as 1,25 times the base plate thickness. 
NOTE 2: Backing plates should be assumed not to affect the rotational stiffness S_{j} of the joint. 
NOTE 3: For welds (k_{19}) the stiffness coefficient should be taken as equal to infinity. This component need not be taken into account when calculating the rotational stiffness S_{j}. 
NOTE 4: For beam flange and web in compression (k_{7}), beam web in tension (k_{8}), plate in tension or compression (k_{9}), haunched beams (k_{20}), the stiffness coefficients should be taken as equal to infinity. These components need not be taken into account when calculating the rotational stiffness S_{j}. 
NOTE 5: Where a supplementary web plate is used, the stiffness coefficients for the relevant basic joint components k_{1} to k_{3} should be increased as follows: 
 
k_{1} for the column web panel in shear should be based on the increased shear area A_{vc} from 6.2.6.1(6); 
 
k_{2} for the column web in compression should be based on the effective thickness of the web from 6.2.6.2(6); 
 
k_{3} for the column web in tension, should be based on the effective thickness of the web from 6.2.6.3(8). 
6.3.3 Endplate joints with two or more boltrows in tension
6.3.3.1 General method
 For endplate joints with two or more boltrows in tension, the basic components related to all of these boltrows should be represented by a single equivalent stiffness coefficient k_{eq} determined from:
where:
h_{r} 
is 
the distance between boltrow r and the centre of compression; 
k_{eff,r} 
is 
the effective stiffness coefficient for boltrow r taking into account the stiffness coefficients k_{i} for the basic components listed in 6.3.3.1(4) or 6.3.3.1(5) as appropriate; 
z_{eq} 
is 
the equivalent lever arm, see 6.3.3.1(3). 
 The effective stiffness coefficient k_{eff,r} for boltrow r should be determined from:
where:
k_{i,r} 
is 
the stiffness coefficient representing component i relative to boltrow r. 
97
 The equivalent lever arm z_{eq} should be determined from:
 In the case of a beamtocolumn joint with an endplate connection, k_{eq} should be based upon (and replace) the stiffness coefficients k_{i} for:
  the column web in tension (k_{3});
  the column flange in bending (k_{4});
  the endplate in bending (k_{5});
  the bolts in tension (k_{10}).
 in the case of a beam splice with bolted endplates, k_{eq} should be based upon (and replace) the stiffness coefficients k_{i} for:
  the endplates in bending (k_{5});
  the bolts in tension (k_{10}).
6.3.3.2 Simplified method for extended endplates with two boltrows in tension
 For extended endplate connections with two boltrows in tension, (one in the extended part of the endplate and one between the flanges of the beam, see Figure 6.20), a set of modified values may be used for the stiffness coefficients of the related basic components to allow for the combined contribution of both boltrows. Each of these modified values should be taken as twice the corresponding value for a single boltrow in the extended part of the endplate.
NOTE: This approximation leads to a slightly lower estimate of the rotational stiffness.
 When using this simplified method, the lever arm z should be taken as equal to the distance from the centre of compression to a point midway between the two boltrows in tension, see Figure 6.20.
Figure 6.20: Lever arm z for simplified method
6.3.4 Column bases
 The rotational stiffness, S_{j}, of a column base subject to combined axial force and bending moment should be calculated using the method given in Table 6.12. This method uses the following stiffness coefficients:
k_{T,1} 
is the tension stiffness coefficient of the left hand side of the joint and the inverse of it should be taken as equal to the sum of the inverses of the stiffness coefficients k_{15} and k_{16} (given in Table 6.11) acting on the left hand side of the joint. 98 
k_{T,r} 
is the tension stiffness coefficient of the right hand side of the joint and the inverse of it should be taken as equal to the sum of the inverses of the stiffness coefficients k_{15} and k_{16} (given in Table 6.11) acting on the right hand side of the joint. 
k_{C,l} 
is the compression stiffness coefficient of the left hand side of the joint and should be taken as equal to the stiffness coefficient k_{13} (given in Table 6.11) acting on the left hand side of the joint. 
k_{C,r} 
is the compression stiffness coefficient of the right hand side of the joint and should be taken as equal to the stiffness coefficient k_{13} (given in Table 6.11) acting on the right hand side of the joint. 
 For the calculation of z_{T,l}, z_{C,l}, z_{T,r}, z_{C,r} see 6.2.8.1.
Table 6.12: Rotational stiffness S_{j} of column bases
Loading 
Lever arm z 
Rotational stiffness S_{j,ini} 
Left side in tension Right side in compression 
z = z_{T,l} + z_{C,r} 
N_{Ed} > 0 and e > z_{T,l} 
N_{Ed} ≤ 0 and e ≤ z_{C,r} 

Left side in tension Right side in tension 
z = z_{T,l} + z_{T,r} 
N_{Ed} > 0 and 0 < e < z_{T,l} 
N_{Ed} > 0 and z_{T,r} < e ≤ 0 

Left side in compression Right side in tension 
z = z_{C,l} + z_{T,r} 
N_{Ed} > 0 and e ≤ z_{T,r} 
N_{Ed} ≤ 0 and e > z_{C,l} 

Left side in compression Right side in compression 
z = z_{C,l} + z_{C,r} 
N_{Ed} ≤ 0 and 0 < e < z_{C,l} 
N_{Ed} ≤ 0 and z_{C,r} < e ≤ 0 

M_{Ed} > 0 is clockwise, N_{Ed} > 0 is tension, μ see 6.3.1(6).

6.4 Rotation capacity
6.4.1 General
 P In the case of rigid plastic global analysis, a joint at a plastic hinge location shall have sufficient rotation capacity.
 The rotation capacity of a bolted or welded joint should be determined using the provisions given in 6.4.2 or 6.4.3. The design methods given in these clauses are only valid for S235, S275 and S355 steel grades and for joints in which the design value of the axial force N_{Ed} in the connected member does not exceed 5% of the design plastic resistance N_{pℓ,Rd} of its crosssection.
 As an alternative to 6.4.2 and 6.4.3 the rotation capacity of a joint need not be checked provided that the design moment resistance M_{j,Rd} of the joint is at least 1.2 times the design plastic moment resistance M_{pl,Rd} of the cross section of the connected member.
99
 In cases not covered by 6.4.2 and 6.4.3 the rotation capacity may be determined by testing in accordance with EN 1990, Annex D. Alternatively, appropriate calculation models may be used, provided that they are based on the results of tests in accordance with EN 1990.
6.4.2 Bolted joints
 A beamtocolumn joint in which the design moment resistance of the joint M_{j,Rd} is governed by the design resistance of the column web panel in shear, may be assumed to have adequate rotation capacity for plastic global analysis, provided that d_{wc}/t_{w} ≤ 69ε .
 A joint with either a bolted endplate or angle flange cleat connection may be assumed to have sufficient rotation capacity for plastic analysis, provided that both of the following conditions are satisfied:
 the design moment resistance of the joint is governed by the design resistance of either:
  the column flange in bending or
  the beam endplate or tension flange cleat in bending.
 the thickness t of either the column flange or the beam endplate or tension flange cleat (not necessarily the same basic component as in (a)) satisfies:
where:
f_{y} 
is 
the yield strength of the relevant basic component; 
d 
is 
the nominal diameter of the bolt; 
f_{ub} 
is 
the ultimate tensile strength of the bolt material. 
 A joint with a bolted connection in which the design moment resistance M_{j,Rd} is governed by the design resistance of its bolts in shear, should not be assumed to have sufficient rotation capacity for plastic global analysis.
6.4.3 Welded Joints
 The rotation capacity ϕ_{Cd} of a welded beamtocolumn connection may be assumed to be not less that the value given by the following expression provided that its column web is stiffened in compression but unstiffened in tension, and its design moment resistance is not governed by the design shear resistance of the column web panel, see 6.4.2(1):
ϕ_{Cd} = 0,025 h_{c}/h_{b} … (6.33)
where:
h_{b} 
is 
the depth of the beam; 
h_{c} 
is 
the depth of the column. 
 An unstiffened welded beamtocolumn joint designed in conformity with the provisions of this section, may be assumed to have a rotation capacity ϕ_{Cd} of at least 0,015 radians.
100
7 Hollow section joints
7.1 General
7.1.1 Scope
 This section gives detailed application rules to determine the static design resistances of uniplanar and multiplanar joints in lattice structures composed of circular, square or rectangular hollow sections, and of uniplanar joints in lattice structures composed of combinations of hollow sections with open sections.
 The static design resistances of the joints are expressed in terms of maximum design axial and/or moment resistances for the brace members.
 These application rules are valid both for hot finished hollow sections to EN 10210 and for cold formed hollow sections to EN 10219, if the dimensions of the structural hollow sections fulfil the requirements of this section.
 For hot finished hollow sections and cold formed hollow sections the nominal yield strength of the end product should not exceed 460 N/mm^{2}. For end products with a nominal yield strength higher than 355 N/mm^{2} , the static design resistances given in this section should be reduced by a factor 0,9.
 The nominal wall thickness of hollow sections should not be less than 2,5 mm.
 The nominal wall thickness of a hollow section chord should not be greater than 25 mm unless special measures have been taken to ensure that the through thickness properties of the material will be adequate.
 For fatigue assessment see EN 199319.
 The types of joints covered are indicated in Figure 7.1.
7.1.2 Field of application
 The application rules for hollow section joints may be used only where all of the conditions given in 7.1.2(2) to 7.1.2(8) are satisfied.
 The compression elements of the members should satisfy the requirements for Class 1 or Class 2 given in EN 199311 for the condition of axial compression .
 The angles θ_{i} between the chords and the brace members, and between adjacent brace members, should satisfy:
θ_{i} ≥ 30°
 The ends of members that meet at a joint should be prepared in such a way that their crosssectional shape is not modified. Flattened end connections and cropped end connections are not covered in this section.
 In gap type joints, in order to ensure that the clearance is adequate for forming satisfactory welds, the gap between the brace members should not be less than (t_{1} + t_{2}).
 In overlap type joints, the overlap should be large enough to ensure that the interconnection of the brace members is sufficient for adequate shear transfer from one brace to the other. In any case the overlap should be at least 25%.
If the overlap exceeds λ_{ov,lim.} = 60% in case the hidden seam of the overlapped brace is not welded or λ_{ov,lim.} = 80% in case the hidden seam of the overlapped brace is welded or if the braces are rectangular sections with h_{i} < b_{i} and/or h_{j} < b_{j}, the connection between the braces and the chord face should be checked for shear.
101
 Where overlapping brace members have different thicknesses and/or different strength grades, the member with the lowest t_{i} f_{yi} value should overlap the other member.
 Where overlapping brace members are of different widths, the narrower member should overlap the wider one.
Figure 7.1: Types of joints in hollow section lattice girders
102
7.2 Design
7.2.1 General
 P The design values of the internal axial forces both in the brace members and in the chords at the ultimate limit state shall not exceed the design resistances of the members determined from EN 199311.
 P The design values of the internal axial forces in the brace members at the ultimate limit state shall also not exceed the design resistances of the joints given in 7.4, 7.5, 7.6 or 7.7 as appropriate.
 The stresses σ_{0,Ed} or σ_{p,Ed} in the chord at a joint should be determined from:
where:
7.2.2 Failure modes for hollow section joints
 The design joint resistances of connections between hollow sections and of connections between hollow sections and open sections, should be based on the following failure modes as applicable:
 Chord face failure (plastic failure of the chord face) or chord plastification (plastic failure of the chord crosssection);
 Chord side wall failure (or chord web failure) by yielding, crushing or instability (crippling or buckling of the chord side wall or chord web) under the compression brace member;
 Chord shear failure;
 Punching shear failure of a hollow section chord wall (crack initiation leading to rupture of the brace members from the chord member);
 Brace failure with reduced effective width (cracking in the welds or in the brace members);
 Local buckling failure of a brace member or of a hollow section chord member at the joint location.
NOTE: The phrases printed in boldface type in this list are used to describe the various failure modes in the tables of design resistances given in 7.4 to 7.7.
 Figure 7.2 illustrates failure modes (a) to (f) for joints between CHS brace and chord members.
 Figure 7.3 illustrates failure modes (a) to (f) for joints between RHS brace and chord members.
 Figure 7.4 illustrates failure modes (a) to (f) for joints between CHS or RHS brace members and I or H section chord members.
 Although the resistance of a joint with properly formed welds is generally higher under tension than under compression, the design resistance of the joint is generally based on the resistance of the brace in compression to avoid the possible excessive local deformation or reduced rotation capacity or deformation capacity which might otherwise occur.
103
Figure 7.2: Failure modes for joints between CHS members
104
Figure 7.3: Failure modes for joints between RHS brace members and RHS chord members
105
Figure 7.4: Failure modes for joints between CHS brace members and RHS brace members and I or H section chord members
106
7.3 Welds
7.3.1 Design resistance
 P The welds connecting the brace members to the chords shall be designed to have sufficient resistance to allow for nonuniform stressdistributions and sufficient deformation capacity to allow for redistribution of bending moments.
 In welded joints, the connection should normally be formed around the entire perimeter of the hollow section by means of a butt weld, a fillet weld, or combinations of the two. However in partially overlapping joints the hidden part of the connection need not be welded, provided that the axial forces in the brace members are such that their components perpendicular to the axis of the chord do not differ by more than 20%.
 Typical weld details are indicated in 1.2.7 Reference Standards: Group 7.
 The design resistance of the weld, per unit length of perimeter of a brace member, should not normally be less than the design resistance of the crosssection of that member per unit length of perimeter.
 The required throat thickness should be determined from section 4.
 The criterion given in 7.3.1(4) may be waived where a smaller weld size can be justified both with regard to resistance and with regard to deformation capacity and rotation capacity, taking account of the possibility that only part of its length is effective.
 For rectangular structural hollow sections the design throat thickness of flare groove welds is defined in Figure 7.5.
Figure 7.5: Design throat thickness of flare groove welds in rectangular structural hollow section
 For welding in coldformed zones, see 4.14.
107
7.4 Welded joints between CHS members
7.4.1 General
 Provided that the geometry of the joints is within the range of validity given in Table 7.1, the design resistances of welded joints between circular hollow section members may be determined using 7.4.2 and 7.4.3.
 For joints within the range of validity given in Table 7.1, only chord face failure and punching shear need be considered. The design resistance of a connection should be taken as the minimum value for these two criteria.
 For joints outside the range of validity given in Table 7.1, all the failure modes given in 7.2.2 should be considered, in addition, the secondary moments in the joints caused by their rotational stiffness should be taken into account.
Table 7.1: Range of validity for welded joints between CHS brace members and CHS chords
Diameter ratio

0.2 ≤ d_{i}/d_{0} ≤ 1,0 
Chords 
tension 
10 ≤ d_{0}/t_{0} ≤ 50 (generally), but: 
compression 
Class 1 or 2 and 10 ≤ d_{0}/t_{0} ≤ 50 (generally), but: 
Braces 
tension 
d_{i}/t_{i} ≤ 50 
compression 
Class 1 or 2 
Overlap 
25% ≤ λ_{ov} ≤ λ_{ov,lim.}, see 7.1.2 (6) 
Gap 
g ≥ t_{1} + t_{2}

7.4.2 Uniplanar joints
 P In brace member connections subject only to axial forces, the design internal axial force N_{i,Ed} shall not exceed the design axial resistance of the welded joint N_{i,Rd} obtained from Table 7.2, Table 7.3 or Table 7.4 as appropriate.
 Brace member connections subject to combined bending and axial force should satisfy:
where:
M_{ip,i,Rd} 
is 
the design inplane moment resistance; 
M_{ip,i,Ed} 
is 
the design inplane internal moment; 
M_{op,i,Rd} 
is 
the design outofplane moment resistance; 
M_{op,i,Ed} 
is 
the design outofplane internal moment. 
108
Table 7.2: Design axial resistances of welded joints between CHS brace members and CHS chords
Chord face failure  T and Y joints 


Chord face failure  X joints 


Chord face failure  K and N gap or overlap joints 


Punching shear failure for K, N and KT gap joints and T, Y and X joints 
[i = 1, 2 or 3] 
When d_{i} ≤ d_{0} – 2t_{0} : 
Factors k_{g} and k_{p} 

For n_{p} > 0 (compression): For n_{p} ≤ 0 (tension): 
k_{p} = 1 – 0,3 n_{p}(1 + n_{p}) k_{p} = 1,0 
but 
k_{p} ≤ 1,0 
109
Table 7.3: Design resistances of welded joints connecting gusset plates to CHS members
Chord face failure 

N_{1,Rd} = k_{p} f_{y0} t_{0}^{2} (4 + 20β^{2}) / γ_{M 5}
M_{ip,1,Rd} = 0
M_{op,1,Rd} = 0,5 b_{1} N_{1,Rd}


M_{ip,1,Rd} = 0
M_{op,1,Rd} = 0,5 b_{1} N_{1,Rd}


N_{1,Rd} = 5k_{p} f_{y0} t_{0}^{2} (1 + 0,25η) / γ_{M 5}
M_{ip,1,Rd} = h_{1} N_{1,Rd}
M_{op,1,Rd} = 0


N_{1,Rd} = 5k_{p} f_{y0} t_{0}^{2} (1 + 0,25η) / γ_{M 5}
M_{ip,1,Rd} = h_{1} N_{1,Rd}
M_{op,1,Rd} = 0

Punching shear failure 

Range of validity 
Factor k_{p} 
In addition to the limits given in Table 7.1:
β ≥ 0,4 
and 
η ≤ 4 
where β = b_{1} / d_{0} 
and 
η = h_{1}/d_{0} 

For n_{p} > 0 (compression):
k_{p} = 1 – 0,3 n_{p}(1 + n_{p}) 
but 
k_{p} ≤ 1,0 
For n_{p} ≤ 0 (tension): 

k_{p} = 1,0 

110
Table 7.4: Design resistances of welded joints connecting I, H or RHS sections to CHS members
Chord face failure 

N_{1,Rd} = k_{p} f_{y0} t_{0}^{2} (4 + 20β^{2})(1 + 0,25η) / γ_{M 5}
M_{ip,1,Rd} = h_{1} N_{1,Rd} / (1 + 0,25η)
M_{op,1,Rd} = 0,5 b_{1} N_{1,Rd}


M_{ip,1,Rd} = h_{1} N_{1,Rd} / (1 + 0,25η)
M_{op,1,Rd} = 0,5 b_{1} N_{1,Rd}


N_{1,Rd} = k_{p} f_{y0} t_{0}^{2} (4 + 20β^{2})(1 + 0,25η) / γ_{M 5}
M_{ip,1,Rd} = h_{1} N_{1,Rd}
M_{op,1,Rd} = 0,5 b_{1} N_{1,Rd}


M_{ip,1,Rd} = h_{1} N_{1,Rd}
M_{op,1,Rd} = 0,5 b_{1} N_{1,Rd}

Punching shear failure 
I or H sections with η > 2 (for axial compression and outofplane bending) and RHS sections: 

All other cases: 

where t_{1} is the flange or wall thickness of the transverse I, H, or RHS section 

Range of validity 
Factor k_{p} 
In addition to the limits given in Table 7.1:

β ≥ 0,4 
and 
η ≤ 4 
where 
β = b_{1} / d_{0} 
and 
η = h_{1}/d_{0} 

For n_{p} > 0 (compression):
k_{p} = 1 – 0,3 n_{p}(1 + n_{p}) 
but 
k_{p} ≤ 1,0 
For n_{p} ≤ 0 (tension): 

k_{p} = 1,0 

111
 The design internal moment M_{i,Ed} may be taken as the value at the point where the centreline of the brace member meets the face of the chord member.
 The design inplane moment resistance and the design outofplane moment resistance M_{i,Rd} should be obtained from Table 7.3, Table 7.4 or Table 7.5 as appropriate.
 The special types of welded joints indicated in Table 7.6 should satisfy the appropriate design criteria specified for each type in that table.
 Values of the factor k_{g} which is used in Table 7.2 for K, N and KT joints are given in Figure 7.6. The factor k_{g} is used to cover both gap type and overlap type joints by adopting g for both the gap and the overlap and using negative values of g to represent the overlap q as defined in Figure 1.3(b).
Figure 7.6: Values of the factor k_{g} for use in table 7.2
112
113
Table 7.6: Design criteria for special types of welded joints between CHS brace members and CHS chords
Type of joint 
Design criteria 
The forces may be either tension or compression but should act in the same direction for both members.

N_{1,Ed} ≤ N_{1,Rd}
where N_{1,Rd} is the value of N_{1,Rd} for an X joint from Table 7.2.

Members 1 and 3 are here in compression and member 2 is here in tension.

N_{1,Ed} sin θ_{1} + N_{3,Ed} sin θ_{3} ≤ N_{1,Rd} sin θ_{1}
N_{2,Ed} sin θ_{2} ≤ N_{1,Rd} sin θ_{1}
where N_{1,Rd} is the value of N_{1,Rd} for a K joint from Table 7.2 but with replaced by:

All bracing members should always be in either compression or tension.

N_{1,Ed} sin θ_{1} + N_{2,Ed} sin θ_{2} ≤ N_{x,Rd} sin θ_{x}
where N_{x,Rd} is the value of N_{x,Rd} for an X joint from Table 7.2, where N_{x,Rd} sin θ_{x} is the larger of:
 N_{1,Rd} sin θ_{1}  and  N_{2,Rd} sin θ_{2} 

Member 1 is always in compression and member 2 is always in tension.

N_{i,Ed} ≤ N_{i,Rd}
where N_{i,Rd} is the value of N_{i,Rd} for a K joint from Table 7.2, provided that, in a gaptype joint, at section 11 the chord satisfies:

114
7.4.3 Multiplanar joints
 In each relevant plane of a multiplanar joint, the design criteria given in 7.4.2 should be satisfied using the reduced design resistances obtained from 7.4.3(2).
 The design resistances for each relevant plane of a multiplanar joint should be determined by applying the appropriate reduction factor μ given in Table 7.7 to the resistance of the corresponding uniplanar joint calculated according to 7.4.2 by using the appropriate chord force for k_{p} .
Table 7.7: Reduction factors for multiplanar joints
Type of joint 
Reduction factor μ 
TT joint 
60° ≤ φ ≤ 90° 
Member 1 may be either tension or compression.

μ = 1,0 
XX joints 
Members 1 and 2 can be either in compression or tension. N_{2,Ed}/N_{1,Ed} is negative if one member is in tension and one in compression.

μ = 1 + 0,33 N_{2,Ed} / N_{1,Ed}
taking account of the sign of N_{1,Ed} and N_{2,Ed} where  N_{2,Ed}  ≤  N_{1,Ed} 

KK joint 
60° ≤ φ ≤ 90° 
Member 1 is always in compression and member 2 is always in tension.

μ = 0,9
provided that, in a gaptype joint, at section 11 the chord satisfies:

115
7.5 Welded joints between CHS or RHS brace members and RHS chord members
7.5.1 General
 Provided that the geometry of the joints is within the range of validity given in Table 7.8, the design resistances of welded joints between hollow section brace members and rectangular or square hollow section chord members may be determined using 7.5.2 and 7.5.3.
 For joints within the range of validity given in Table 7.8, only the design criteria covered in the appropriate table need be considered. The design resistance of a connection should be taken as the minimum value for all applicable criteria.
 For joints outside the range of validity given in Table 7.8, all the failure modes given in 7.2.2 should be considered. In addition, the secondary moments in the joints caused by their rotational stiffness should be taken into account.
Table 7.8: Range of validity for welded joints between CHS or RHS brace members and RHS chord members
Type of joint 
Joint parameters [ i = 1 or 2, j = overlapped brace] 
b_{i} / b_{0} or d_{1} / b_{0} 
b_{i} / t_{i} and h_{i} / t_{i} or d_{i} / t_{i} 
h_{0} / b_{0} and h_{i} / b_{i} 
b_{0} / t_{0} and h_{0} / t_{0} 
Gap or overlap
b_{i} / b_{j}

Compression 
Tension 
T, Y or X 
b_{i} / b_{0} ≥ 0,25 
b_{i} / t_{i} ≤ 35
and
h_{i} / t_{i} ≤ 35
and
Class 1 or 2

b_{i} / t_{i} ≤ 0,35
and
h_{i} / t_{i} ≤ 0,35

≥ 0,5
but
≤ 2,0

≤ 35
and
Class 1 or 2

– 
K gap
N gap

b_{i} / b_{0} ≥ 0,35 and
≥ 0,1 + 0,01 b_{0} / t_{0}

≤ 35
and
Class 1 or 2

g / b_{0} ≥ 0,5(1 – β) but ≤ 1,5(1 – β)_{1)}
and as a minimum
g ≥ t_{1} + t_{2}

K overlap
N overlap

b_{i} / b_{0} ≥ 0,25 
Class 1 
Class 1 or 2 
25% ≤ λ_{ov} ≤ λ_{ov,lim.}^{2)}
b_{i} / b_{j} ≤ 0,75

Circular brace member 
d_{i} / b_{0} ≥ 0,4
but ≤ 0,8

Class 1 
d_{i} / t_{i} ≤ 50 
As above but with d_{i} replacing b_{i} and d_{j} replacing b_{j}. 
^{1)} If g/b_{0} > 1,5(1 – β) and g > t_{1} + t_{2} treat the joint as two separate T or Y joints.
^{2)} λ_{ov,lim.} = 60% if the hidden seam is not welded and 80% if the hidden seam is welded. If the overlap exceeds λ_{ov,lim.} or if the braces are rectangular sections with h_{i} < b_{i} and/or h_{j} < b_{j}, the connection between the braces and chord face has to be checked for shear.

116
7.5.2 Uniplanar joints
7.5.2.1 Unreinforced joints
 In brace member connections subject only to axial forces, the design internal axial force N_{i,Ed} should not exceed the design axial resistance of the welded joint N_{i,Rd} , determined from 7.5.2.1(2) or 7.5.2.1(4) as appropriate.
 For welded joints between square or circular hollow section brace members and square hollow section chord members only, where the geometry of the joints is within the range of validity given in Table 7.8 and also satisfies the additional conditions given in Table 7.9, the design axial resistances may be determined from the expressions given in Table 7.10.
 For joints within the range of validity of Table 7.9, the only design criteria that need be considered are chord face failure and brace failure with reduced effective width. The design axial resistance should be taken as the minimum value for these two criteria.
NOTE: The design axial resistances for joints of hollow section brace members to square hollow section chords given in Table 7.10 have been simplified by omitting design criteria that are never critical within the range of validity of Table 7.9.
 The design axial resistances of any unreinforced welded joint between CHS or RHS brace members and RHS chords, within the range of validity of Table 7.8, may be determined using the expressions given in text deleted Table 7.11, Table 7.12 or Table 7.13 as appropriate. For reinforced joints see 7.5.2.2.
Table 7.9: Additional conditions for the use of Table 7.10
Type of brace 
Type of joint 
Joint parameters 
Square hollow section 
T, Y or X 
b_{i}/b_{0} ≤ 0,85 
b_{0}/t_{0} ≥ 10 
K gap or N gap 

b_{0}/t_{0} ≥ 15 
Circular hollow section 
T, Y or X 

b_{0}/t_{0} ≥ 10 
K gap or N gap 

b_{0}/t_{0} ≥ 15 
117
Table 7.10: Design axial resistances of welded joints between square or circular hollow section
Type of joint 
Design resistance [i = 1 or 2, j = overlapped brace] 
T, Y and X joints 
Chord face failure 
β ≤ 0,85 


K and N joints 
Chord face failure 
β ≤ 1,0 


K, N and overlap joints ^{*)} 
Brace failure 
25% ≤ λ_{ov} < 50% 
Member i or member j may be either tension or compression but one should be tension and the other compression


Brace failure 
50% ≤ λ_{ov} < 80% 

Brace failure 
λ_{ov} ≥ 80% 

Parameters b_{eff}, b_{c,ov} and k_{n} 

For n > 0 (compression): 




but 
k_{n} ≤ 1,0 
For n ≤ 0 (tension): 


k_{n} ≤ 1,0 
For circular braces, multiply the above resistances by π/4, replace b_{1} and h_{1} by d_{1} and replace b_{2} and h_{2} by d_{2} 
*) Only the overlapping brace member i need be checked. The brace member efficiency (i.e. the design resistance of the joint divided by the design plastic resistance of the brace member) of the overlapped brace member j should be taken as equal to that of the overlapping brace member.
See also Table 7.8. 
118
Table 7.11: Design axial resistances of welded T, X and Y joints between RHS or CHS braces and RHS chords
Type of joint 
Design resistance 

Chord face failure 
β ≤ 0,85 

Chord side wall buckling ^{1)} 
β = 1,0^{2)} 

Brace failure 
β ≥ 0,85 
N_{1,Rd} = f_{yi}t_{1} (2h_{1} – 4t_{1} + 2b_{eff}) / γ_{M 5} 
Punching shear 
0,85 ≤ β ≤ (1  1/γ) 

^{1)} For X joints with cosθ_{1} > h_{1}/h_{0} use the smaller of this value and the design shear resistance of the chord side walls given for K and N gap joints in Table 7.12.
^{2)} For 0,85 ≤ β ≤ 1,0 use linear interpolation between the value for chord face failure at β = 0,85 and the governing value for chord side wall failure at β = 1,0 (side wall buckling or chord shear).

For circular braces, multiply the above resistances by π/4, replace b_{1} and h_{1} by d_{1} and replace b_{2} and h_{2} by d_{2}. 
For tension:
f_{b} = f_{y0}
For compression:
f_{b} = χ f_{y0} (T and Y joints)
f_{b} = 0,8 χ f_{y0} sin θ_{1} (X joints)
where χ is the reduction factor for flexural buckling obtained from EN 199311 using the relevant buckling curve and a normalized slenderness determined from:



For n > 0 (compression): 
For n ≤ 0 (tension): 
but 


119
120
Table 7.13: Design resistances of welded joints connecting gusset plates or I or H sections to RHS members
Transverse plate 
Chord face failure β ≤ 0,85 


Chord side wall crushing 
when b_{1} ≥ b_{0} – 2t_{0} 
N_{1,Rd} = k_{n}f_{y0}t_{0} (2t_{1} + 10t_{0}) / γ_{M 5} 
Punching shear 
when b_{1} ≥ b_{0} – 2t_{0} 

Longitudinal plate 
Chord face failure 


I or H section 

As a conservative approximation, if , N_{1,Rd} for an I or H section may be assumed to be equal to the design resistance of two transverse plates of similar dimensions to the flanges of the 1 or H section, determined as specified above.
If , a linear interpolation between one and two plates should be made.
M_{ip,1,Rd} = N_{1,Rd} (h_{1} – t_{1})
N_{1,Rd} is the capacity of one flange; β is the ratio of the width of the flange of the 1 or H brace section and the width of the RHS chord.

Range of validity 
In addition to the limits given in Table 7.8:
0,5 ≤ β ≤ 1,0 b_{0}/t_{0} ≤ 30

Parameters b_{eff}, b_{e,p} and k_{m} 

For n > 0 (compression): 
For n ≤ 0 (tension): 
but 
k_{m} = 1,3(1 – n) k_{m} ≤ 1,0 k_{m} = 1,0 


*) Fillet welded connections should be designed in accordance with 4.10. 
121
 Brace member connections subjected to combined bending and axial force should satisfy the following requirement:
where:
M_{ip,i,Rd} 
is 
the design inplane moment resistance 
M_{ip,i,Ed} 
is 
the design inplane internal moment 
M_{op,i,Rd} 
is 
the design outofplane moment resistance 
M_{op,i,Ed} 
is 
the design outofplane internal moment 
 The design internal moment M_{i,Ed} may be taken as the value at the point where the centreline of the brace member meets the face of the chord member.
 For unreinforced joints, the design inplane moment resistance and design outofplane moment resistance M_{i,Rd} should be obtained from Table 7.13 or Table 7.14 as appropriate. For reinforced joints see 7.5.2.2.
 The special types of welded joints indicated in Table 7.15 and Table 7.16 should satisfy the appropriate design criteria specified for each type in that table.
7.5.2.2 Reinforced joints
 Various types of joint reinforcement may be used. The appropriate type depends upon the failure mode that, in the absence of reinforcement, governs the design resistance of the joint.
 Flange reinforcing plates may be used to increase the resistance of the joint to chord face failure, punching shear failure or brace failure with reduced effective width.
 A pair of side plates may be used to reinforce a joint against chord side wall failure or chord shear failure.
 In order to avoid partial overlapping of brace members in a K or N joint, the brace members may be welded to a vertical stiffener.
 Any combinations of these types of joint reinforcement may also be used.
 The grade of steel used for the reinforcement should not be lower than that of the chord member.
 The design resistances of reinforced joints should be determined using Table 7.17 and Table 7.18.
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Table 7.14: Design resistance moments of welded joints between RHS brace members and RHS chords
T and X joints 
Design resistance 
Inplane moments (θ = 90°) 
Chord face failure 
β ≤ 0,85 


Chord side wall crushing 
0,85 < β ≤ 1,0 
M_{ip,l,Rd} = 0,5 f_{yk} t_{0} (h_{1} + 5t_{0})^{2} / γ_{M5}
f_{yk} = f_{y0} 
for T joints 
f_{yk} = 0,8 f_{y0} 
for X joints 

Brace failure 
0,85 < β ≤ 1,0 
M_{ip,l,Rd} = f_{yl} (W_{pl,1} − (1 − b_{eff} / b_{1})b_{1} (h_{1} − t_{1})t_{1}) / γ_{M5} 
Outofplane moments (θ = 90°) 
Chord face failure 
β ≤ 0,85 


Chord side wall crushing 
0,85 < β ≤ 1,0 
M_{op,l,Rd} = f_{yk} t_{0} (b_{0} − t_{0})(h_{1} + 5t_{0}) / γ_{M5}
f_{yk} = f_{y0} 
for T joints 
f_{yk} = 0,8 f_{y0} 
for X joints 

Chord distortional failure (T joints only) *) 

Brace failure 
0,85 < β ≤ 1,0 
M_{op,l,Rd} = f_{yl} (W_{pl,1} − 0,5 (1 − b_{eff} / b_{1})^{2} b_{1}^{2} t_{1})/ γ_{M5} 
Parameters b_{eff} and k_{n} 
but b_{eff} ≤ b_{1}

For n > 0 (compression): 
For n ≤ 0 (tension): 
but 
k_{n} ≤ 1,0 k_{n} = 1,0 

*) This criterion does not apply where chord distortional failure is prevented by other means. 
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Table 7.15: Design criteria for special types of welded joints between RHS brace members and RHS chords
Type of joint 
Design criteria 
The members may be in either tension or compression and should act as in the same direction for both members.

N_{1,Rd} ≤ N_{1,Rd}
where N_{1,Rd} is the value of N_{1,Rd} for an X joint from Table 7.11.

The member 1 is always in compression and member 2 is always in tension.

N_{1,Ed} sin θ_{1} + N_{3,Ed} sin θ_{3} ≤ N_{1,Rd} sin θ_{1} N_{2,Ed} sin θ_{2} ≤ N_{1,Rd} sin θ_{1}
where N_{1,Rd} is the value of N_{1,Rd} for a K joint from
Table 7.12, but with
replaced by:

All bracing members should be either compression or tension.

N_{1,Ed} sin θ_{1} + N_{2,Ed} sin θ_{2} ≤ N_{x,Rd} sin θ_{x}
where N_{x,Rd} is the value of N_{x,Rd} for an X joint from Table 7.11, and N_{x,Rd} θ_{x} is the larger of:
 N_{1,Rd} sin θ_{1}  and  N_{2,Rd} sin θ_{2} 

Member 1 is always in compression and member 2 is always in tension.

N_{i,Ed} ≤ N_{i,Rd}
where N_{i,Rd} is the value of N_{i,Rd} for a K joint from Table 7.12, provided that, in a gaptype joint, at section 11 the chord satisfies:

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Table 7.16: Design criteria for welded knee joints and crankedchord joints in RHS members
Type of joint 
Criteria 
Welded knee joints 

The crosssection should be Class 1 for pure bending, see EN 199311.
N_{Ed} ≤ 0,2N_{pℓ,Rd}
and
If θ ≤ 90°: 

If 90° < θ ≤ 180: 

where k_{90} is the value of k for θ = 90°.


t_{p} ≥ 1,5t and ≥ 10 mm

Crankedchord 

N_{i,Ed} ≤ N_{i,Rd}
where N_{i,Rd} is the value of N_{i,Rd} for a K or N overlap joint from Table 7.12.

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Table 7.17: Design resistances of reinforced welded T, Y and X joints between RHS or CHS brace members and RHS chords
Type of joint 
Design resistance 
Reinforced with flange plates to avoid chord face failure, brace failure or punching shear. 
Tension loading 
β_{p} ≤ 0,85 


Compression loading 
β_{p} ≤ 0,85 

and
b_{p} ≥ b_{0} − 2t_{0} t_{p} ≥ 2t_{1}
Take N_{1,Rd} as the value of N_{1,Rd} for a T, X or Y joint from Table 7.11, but with k_{n} = 1,0 and t_{0} replaced by t_{p} for chord face failure, brace failure and punching shear only.

Reinforced with side plates to avoid chord side wall buckling or chord side wall shear. 

ℓ_{p} ≥ 1,5h_{1} / sin θ_{1} t_{p} ≥ 2t_{1}
Take N_{1,Rd} as the value of N_{1,Rd} for a T, X or Y joint from Table 7.11, but with t_{0} replaced by (t_{0} + t_{p}) for chord side wall buckling failure and chord side wall shear failure only.

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Table 7.18: Design resistances of reinforced welded K and N joints between RHS or CHS brace members and RHS chords
Type of joint 
Design resistance [i = 1 or 2] 
Reinforced with flange plates to avoid chord face failure, brace failure or punching shear. 

b_{p} ≥ b_{0} − 2t_{0} t_{p} ≥ 2t_{1} and 2t_{2}
Take N_{i,Rd} as the value of N_{i,Rd} for a K or N joint from Table 7.12, but with t_{0} replaced by t_{p} for chord face failure, brace failure and punching shear only.

Reinforced with a pair of side plates to avoid chord shear failure. 

Take N_{i,Rd} as the value of N_{i,Rd} for a K or N joint from Table 7.12, but with t_{0} replaced by (t_{0} + t_{p}) for chord shear failure only.

Reinforced by a division plate between the brace members because of insufficient overlap. 

t_{p} ≥ 2t_{1} and 2t_{2}
Take N_{i,Rd} as the value of N_{i,Rd} for a K or N overlap joint from Table 7.12 with λ_{ov} < 80%, but with and b_{j}, t_{j} and f_{yj} replaced by b_{p}, t_{p} and f_{yp} in the expression for b_{c,ov} given in Table 7.10.

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7.5.3 Multiplanar joints
 In each relevant plane of a multiplanar joint, the design criteria given in 7.5.2 should be satisfied using the reduced design resistances obtained from 7.5.3(2).
 The design resistances for each relevant plane of a multiplanar joint should be determined by applying the appropriate reduction factor μ given in Table 7.19 to the resistance of the corresponding uniplanar joint calculated according to 7.5.2 with the appropriate chord load in the multiplanar situation.
Table 7.19: Reduction factors for multiplanar joints
Type of joint 
Reduction factor μ 
TT joint 
60° ≤ φ ≤ 90° 
Member 1 may be either tension or compression.

μ = 0,9 
XX joint 
Members 1 and 2 can be either in compression or tension. N_{2,Ed}/N_{1,Ed} is negative if one member is in tension and one in compression.

μ = 0,9(1 + 0,33N_{2,Ed} / N_{1,Ed})
taking account of the sign of N_{1,Ed} and N_{2,Ed}
where  N_{2,Ed}  ≤  N_{1,Ed} 

KK joint 
60° ≤ φ ≤ 90° 

μ = 0,9
provided that, in a gaptype joint, at section 11 the chord satisfies:

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7.6 Welded joints between CHS or RHS brace members and I or H section chords
 Provided that the geometry of the joints is within the range of validity given in Table 7.20, the design resistances of the joints should be determined using the expressions given in Table 7.21 or Table 7.22 as appropriate.
Table 7.20: Range of validity for welded joints between CHS or RHS brace members and I or H section chord members
Type of joint 
Joint parameter [i = 1 or 2, j = overlapped brace] 
d_{w}/t_{w} 
b_{i}/t_{i} and h_{i}/t_{i} or d_{i}/t_{i} 
h_{i}/b_{i} 
b_{0}/t_{f} 
b_{i}/b_{j} 
Compression 
Tension 
X 
Class 1
and
d_{w} ≤ 400 mm 


≥ 0,5 but ≤ 2,0 
Class 1 or 2 
– 
T or Y 
Class 1 or 2
and
d_{w} ≤ 400 mm 
1,0 
– 
K gap
N gap 
K overlap
N overlap 
≥ 0,5 but ≤ 2,0 
≥ 0,75 25% ≤ λ_{ov} ≤ λ_{ov,lim.} ^{1)} 
^{1)} λ_{ov,lim.} = 60% if the hidden seam is not welded and 80% if the hidden seam is welded. If the overlap exceeds λ_{ov,lim.} or if the braces are rectangular sections with h_{i} < b_{i} and/or h_{j} < b_{j}, the connection between the braces and chord face has to be checked for shear. 
 For joints within the range of validity given in Table 7.20, only the failure modes covered in the appropriate table need be considered. The design resistance of a connection should be taken as the minimum value for all applicable criteria.
 For joints outside the range of validity given in Table 7.20, all the failure modes given in 7.2.2 should be considered. In addition, the secondary moments in the joints caused by their rotational stiffness should be taken into account.
 In brace member connections subjected only to axial forces, the design axial force N_{i,Ed} should not exceed the design axial resistance of the welded joint N_{i,Rd}, determined from Table 7.21.
 Brace member connections subject to combined bending and axial force should satisfy:
where:
M_{ip,i,Rd} 
is 
the design inplane moment resistance; 
M_{ip,i,Ed} 
is 
the design inplane internal moment. 
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Table 7.21: Design resistances of welded joints between RHS or CHS brace members and I or H section chords
Type of joint 
Design resistance [i = 1 or 2, j = overlapped brace] 
T, Y and X joints 
Chord web yielding 


Brace failure 
N_{l,Rd} = 2f_{yl}t_{l} p_{eff}/γ_{M}_{5} 
K and N gap joints 
Chord web yielding 
Brace failure need not be checked if:
g/t_{f} ≤ 20 − 28β; β ≤ 1,0 − 0,03γ
where γ = b_{0}/2t_{f}
and for CHS:
0,75 ≤ d_{1}/d_{2} ≤ 1,33
or for CHS:
0,75 ≤ b_{1}/b_{2} ≤ 1,33 


Brace failure 
N_{l,Rd} = 2f_{yi}t_{i} p_{eff}/γ_{M}_{5} 
Chord Shear 

K, N and overlap joints ^{*)} 
Brace failure 
25% ≤ λ_{ov} < 50% 
Members i and j may be in either tension or compression


Brace failure 
50% ≤ λ_{ov} < 80% 
N_{i,Rd} = f_{yi}t_{i} (b_{eff} + b_{e,ov} + 2h_{i} − 4t_{i})/γ_{M}_{5} 
Brace failure 
λ_{ov} ≥ 80% 
N_{i,Rd} = f_{yi}t_{i} (b_{i} + b_{e,ov} + 2h_{i} − 4t_{i})/γ_{M}_{5} 
A_{V} = A_{0} − (2 − α) b_{0} t_{f} + (t_{w} + 2R) t_{f}
For RHS:
For CHS: α = 0

p_{eff} = t_{w} + 2r + 7t_{f}f_{y0}/f_{yi}
but for T, Y, X joints and K and N gap joints:
p_{eff} ≤ b_{i} + h_{i} − 2t_{i}
but for K and N overlap joints: p_{eff} ≤ b_{i} 
but
b_{w} ≤ 2t_{i} + 10(t_{f} + r)

but b_{e,ov} ≤ b_{i} 
For CHS braces multiply the above resistances for brace failure by π/4, replace b_{1} and h_{1} by d_{1} and replace b_{2} and h_{2} by d_{2}, except for chord shear. 
*) Only the overlapping brace member i need be checked. The efficiency (i.e. the design resistance of the joint divided by the design plastic resistance of the brace member) of the overlapped brace member j should be taken as equal to that of the overlapping brace member. See also Table 7.20. 
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 The design internal moment M_{i,Ed} may be taken as the value at the point where the centreline of the brace member meets the face of the chord member.
 The design inplane moment resistance M_{ip,l,Rd} should be obtained from Table 7.22.
 If stiffeners in the chord (see Figure 7.7) are used, then the design brace failure resistance N_{i,Rd} for T, X, Y, Kgap and Ngap joints (Table 7.22) is determined as follows:
N_{i,Rd} = 2 f_{yi} t_{i} (b_{eff} + b_{eff,s}) / γ_{M5} … (7.6)
where:
b_{eff} = t_{w} + 2r + 7 t_{f} f_{y0} / f_{yi} 
but 
≤ b_{i} + h_{i} − 2t_{i} 
b_{eff,s} = t_{s} + 2a + 7 t_{f} f_{y0} / f_{yi} 
but 
≤ b_{i} + h_{i} − 2t_{i} 
b_{eff} + b_{eff,s} ≤ b_{i} + h_{i} − 2t_{i} 
where:
a 
is stiffener weld throat thickness, ‘2a’ becomes ‘a’ if single sided fillet welds are used; 
s 
refers to the stiffener. 
 The stiffeners should be at least as thick as the Isection web.
Table 7.22: Design moment resistances of welded joints between rectangular hollow section brace members and I or H section chords
Type of joint 
Design resistance [i = 1 or 2, j = overlapped brace] 
T and Y joints 
Chord web yielding 

M_{ip,l,Rd} = 0,5 f _{y0}t_{w}b_{w} (h_{1} − t_{1}) / γ _{M5} 
Brace failure 
M_{ip,l,Rd} = f _{y1}t_{1}p_{eff} h_{z} / γ _{M5} 
Parameters p_{eff} and b_{w} 
p_{eff} = t _{w} + 2r + 7 t _{f} f _{y0} / f _{y1} but p_{eff} ≤ b_{1} + h_{1} + 2t_{1} 

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Figure 7.7: Stiffeners for lsection chords
7.7 Welded joints between CHS or RHS brace members and channel section chord members
 Provided that the geometry of the joints is within the range of validity given in Table 7.23, the design resistances of welded joints between hollow section brace members and channel section chord members may be determined using Table 7.24.
 The secondary moments in the joints caused by their bending stiffness should be taken into account.
 In a gap type joint, the design axial resistance of the chord crosssection N_{0,Rd} should be determined allowing for the shear force transferred between the brace members by the chord, neglecting the associated secondary moment. Verification should be made according to EN 199311.
Table 7.23: Range of validity for welded joints between CHS or RHS brace members and channel section chord
Type of joint 
Joint parameter [i = 1 or 2, j = overlapped brace] 
b_{i}/b_{0} 
b_{i}/t_{i} and h_{i}/t_{i} or d_{i}/t_{i} 
h_{i}/b_{i} 
b_{0}/t_{0} 
Gap or overlap b_{i}/b_{j} 
Compression 
Tension 
K gap
N gap 
≥ 0,4
and
b_{0} ≤ 400 mm 


≥ 0,5 but ≤ 2,0 
Class 1 or 2 
0,5(1−β*) ≤ g/b_{0}* ≤ 1,5(1−β*) ^{1)}
and
g ≥ t_{1} + t_{2} 
K overlap
N overlap 
≥ 0,25
and
b_{0} ≤ 400 mm 
25% ≤ λ_{ov} ≤ λ_{ov,lim.} ^{2)}
b_{i}/b_{j} ≥ 0,75 
β* = b_{1}/b_{0}* b_{0}* = b_{0} − 2 (t_{w} + r_{0})
^{l)} This condition only apply when β ≤ 0,85.
^{2)} λ_{ov,lim.} = 60% if the hidden seam is not welded and 80% if the hidden seam is welded. If the overlap exceeds λ_{ov,lim.} or if the braces are rectangular sections with h_{i} < b_{i} and/or h_{j} < b_{j}, the connection between the braces and chord face has to be checked for shear.

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Table 7.24: Design resistance of welded joints between RHS or CHS brace members and channel section chords
Type of joint 
Design resistance [i = 1 or 2, j = overlapped brace] 
K and N gap joints 
Brace failure 

N_{i,Rd} = f_{yi}t_{i} (b_{i} + b_{eff} + 2h_{i} − 4t_{i})/γ_{M}_{5} 
Chord failure 

K, N and overlap joints ^{*)} 
Brace failure 
25% ≤ λ_{ov} < 50% 


Brace failure 
50% ≤ λ_{ov} < 80% 
N_{i,Rd} = f_{yi}t_{i} (b_{eff} + b_{e,ov} + 2h_{i} − 4t_{i})/γ_{M}_{5} 
Brace failure 
λ_{ov} ≥ 80% 
N_{i,Rd} = f_{yi}t_{i} (b_{i} + b_{e,ov} + 2h_{i} − 4t_{i})/γ_{M}_{5} 
A_{v} = A_{0} − (1 − α) b_{0}^{*} t_{0}
b_{0}^{*} = b_{0}  2 (t_{w} + r_{0})
For RHS:
For CHS: α = 0
V_{Ed} = (N_{i,Ed} sin θ_{i})_{max} 

For CHS braces except for the chord shear , multiply the above resistances by π/4, replace b_{1} and h_{1} by d_{1} and replace b_{2} and h_{2} by d_{2} 
*) Only the overlapping brace member i need be checked. The efficiency (i.e. the design resistance of the joint divided by the design plastic resistance of the brace member) of the overlapped brace member j should be taken as equal to that of the overlapping brace member. 
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