Inelastic Cyclic Model for Steel Braces

A beam-column element that can accurately model the inelastic cyclic behavior of steel braces is presented. A bounding surface plasticity model in stress-resultant space coupled with a backward Euler algorithm is used to keep track of spread of plasticity through the cross section. Deterioration of cross-section stiffness due to local buckling is accounted for through a damage model. The proposed formulation has been implemented in a large deformation analysis program and is shown to be capable of predicting with reasonable accuracy the experimentally observed inelastic behavior of a variety of members subjected to reversed cyclic loading and a subassemblage under simulated seismic conditions.