STATIC/DYNAMIC ANALYSIS OF LOCALLY BUCKLED FRAMES.

The static and dynamic behavior of plane frames composed of thin-walled steel members is presented. Frame analysis includes post-local-buckling and/or first-order geometric nonlinearities. Post-local-buckling behavior is included using the effective width concept, which includes both axial and bending stresses. Direct iteration is used to calculate the effective cross section properties for members that have locally buckled. An exact elastic stiffness matrix, finite element geometric stiffness, consistent mass and Rayleigh damping matrix formulation is used to discretize the dynamic equilibrium equations. The nonlinear dynamic equations are solved using a modified Newton-Raphson iteration strategy coupled with Newmark's time integration scheme