Some Issues in the Collapse Analysis of Frame Structures

Based on generalized functions, a mixed hinge model for beam-column members was proposed, which can be applied in describing discontinuous displacements in the collapse process of structures. The governing equations were built in the current unstressed configuration. Meanwhile, a Lagrangian multiplier approach was introduced for the analysis of collisions, where no assumption of rigid body with soft surface is needed. As demonstrations, a portal frame subjected to monotonously increasing lateral force, as well as a beam freeing to collide into the ground, was analyzed. Some conclusions were drawn out.