Elastic limit state flexural-torsional postbuckling analysis of bars with open thin-walled cross-sections under axial thrust

This work deals with the elastic limit state flexural-torsional postbucklin g analysis of simply supported bars with open thin-walled asymmetric cross- sections under axial thrust. As it is well known stocky bars with the above type of cross-sections always fail by flexural-torsional buckling in the c ase of asymmetric cross-sections (whose centroid does not coincide with the shear centre), while in the case of monosymmetric cross-sections the failu re may occur either through flexural (Euler) buckling or flexural-torsional buckling depending on the geometric characteristics of the bars. In all th e above three cases the critical state is associated with postbuckling stre ngth. In this paper attention focuses on the first yielding occurring at th e initial part of the post-critical path of flexural-torsional buckling. Th is is, in case of bars made from ideal elastic-ideal plastic material, asso ciated with the maximum combined normal stress, due to axial compression, b ending and warping, which, along with the nonlinear equilibrium equation, y ield the maximum (ultimate) elastic load-carrying capacity. The elastic lim it state postbuckling analysis given here is demonstrated with the aid of e qual-leg angles commonly used in trusses. (C) 1999 Elsevier Science Ltd. Al l rights reserved.