Optimal design of steel frames to enhance overall stability

Abstract

The overall stability of a planar framed structure can be enhanced by maximizing the fundamental linear elastic buckling eigenvalue of the structure, holding the total weight fixed. In its simplest form, the optimality criteria for this objective is that the combined axial and flexural strain energy of the structure, bent in the fundamental buckling mode, be distributed in accord with the weight distribution of the structure. An algorithm to achieve this object involves the solution of the linearized buckling eigenvalue problem as the main computational task. The resulting structure has a limit load considerably higher than the initial design. In addition to increased strength, the structure will also generally exhibit improved post-limit behavior.