Joints - The Behaviour and Design of Steel Structures to EC3 - page 404

Applied force

Applied force

Prying
force

Prying
force

Bolt forces

(a) Bolted T-stub assembly (b) Prying action

Figure 9.13 T-stub elements.

Supporting
member

Supporting
member

Supporting
member

Angle cleat

Top cleat

R Ed R Ed

R Ed

Beam Beam Beam

End plate

Angle seat

(a) Angle seat (b) Flexible end plate (c) Angle cleat

Figure 9.14 Common flexible end joints.

9.4.2.3 Design moment stiffness

Jointsneedtobeclassifiedforframeanalysispurposes(Chapter8)asbeingeither
effectively pinned (low moment stiffness), semi-rigid, or effectively rigid (high-
momentstiffness).Whenajointcannotbeassumedtobeeithereffectivelypinned
orrigid,thenitsmomentstiffnessneedstobedeterminedsothatitcanbeclassified.
If a frame is to be analysed as if semi-rigid (Section 8.3.3), then the moment
stiffnesses of its semi-rigid joints need to be used in the analysis.
In the component method used in Clause 6.3 of EC3-1-8 [1], the moment stiff-
ness of a joint is determined from the inverse of the sum of the flexibilities of the
componentsusedateachlinkinthechainofforcetransferthroughthejoint.Thus
theflexibilitiesofanyplateorcleatcomponentsusedmustbeincludedwiththose
of the fasteners. Plates are comparatively stiff (and often assumed to be rigid)
whenloadedintheirplanes,butarecomparativelyflexiblewhenbentoutoftheir
planes.Ingeneral,theoverallbehaviourofajointcanbeassessedbydetermining
the path by which force is transferred through the joint, and by synthesising the
responses of all the components to their individual loads.