Elastic-plastic instability of flexibly connected non-orthogonal frames

Abstract

A nonlinear elastic-plastic instability analysis of plane non-orthogonal frames, with or without elastic rotational restraints at the supports and semi-rigid connections is presented. The nonlinear flexible connections are represented by polynomial models. Both stability and strength are incorporated in the analysis. The effect of slenderness ratio, elastic rotational restraint at the supports, rise to span ratio and semi-rigid connections are fully assessed. In most cases considered, failure occurs through plastic collapse. It is found that in some cases limit point instability can occur before plastic collapse. From the geometries analyzed, it is concluded that for design application the assumption of linear (instead of nonlinear, polynomial) connection behavior is not adequate for gabled frames.