GENERALIZED ELASTIC BUCKLING OF RESTRAINED I-BEAMS BY FEM

Beam-columns of a doubly symmetric cross section generally experience overall buckling in a lateral-torsional mode. Members with thin webs a nd stocky flanges have been shown in a number of studies to buckle in a so-called lateral-distortional mode, involving distortion of the web of the I-section in the plane of its cross section. For simply suppor ted members, it has been shown further that the effects of this web di stortion in reducing the overall buckling load is not great. This is n ot the case for members with elastic restraint, where distortion of th e web can be of significance in the buckling behavior. This paper deve lops a general line-type finite element with 16 degrees of freedom tha t can be used to study the elastic buckling of restrained I-section be am-columns. The accuracy of the method is demonstrated, and the stabil ity of an elastically restrained half-through girder is studied.