A simple nonlinear frame element and its application to postbuckling analysis

摘要

Based on the assumption of small strains, small rotations, and small displacements, the elastic stiffness matrix and geometric stiffness matrix are derived for a two-dimensional frame element using the force-displacement relations well known in mechanics of materials. This approach is referred to as a direct approach, which differs from the conventional ones in that there is no need to deal with terms such as variations, potential energy, nonlinear strains, etc. Through consideration of the rigid body properties of initially stressed elements, the proposed element matrices have been successfully employed in the postbuckling analysis of structural frames. The advantage of the present approach is its simplicity and clear physical meanings involved.