Local buckling of thin-plate elements - The Behaviour and Design of Steel Structures to EC3 - page 100

Local buckling of
thin-plate elements
4.1Introduction
The behaviour of compression members was discussed in Chapter 3, where it
was assumed that no local distortion of the cross-section took place, so that
failure was only due to overall buckling and yielding. This treatment is appro-
priate for solid section members, and for members whose cross-sections are
composed of comparatively thick-plate elements, including many hot-rolled steel
sections.
However,insomecasesthemembercross-sectioniscomposedofmoreslender-
plateelements,asforexampleinsomebuilt-upmembersandinmostlight-gauge,
cold-formedmembers.Theseslender-plateelementsmaybucklelocallyasshown
in Figure 4.1, and the member may fail prematurely, as indicated by the reduc-
tion from the full line to the dashed line in Figure 4.2. A slender-plate element
doesnotfailbyelasticbuckling,butexhibitssignificantpost-bucklingbehaviour,
as indicated in Figure 4.3. Because of this, the plate's resistance to local fail-
ure depends not only on its slenderness, but also on its yield strength and
residual stresses, as shown in Figure 4.4. The resistance of a plate element
of intermediate slenderness is also influenced significantly by its geometrical
imperfections, while the resistance of a stocky-plate element depends primar-
ily on its yield stress and strain-hardening moduli of elasticity, as indicated in
Figure 4.4.
In this chapter, the behaviour of thin rectangular plates subjected to in-plane
compression, shear, bending, or bearing is discussed. The behaviour under com-
pression is applied to the design of plate elements in compression members and
compression flanges in beams. The design of beam webs is also discussed, and
the influence of the behaviour of thin plates on the design of plate girders to EC3
is treated in detail.