Finite-element analysis of a composite frame under large lateral cyclic loading

This paper presents finite-element (FE) modeling and nonlinear analysis of steel-concrete composite frames subjected to very large cyclic loading. A three-dimensional FE model is developed to carry out the nonlinear analysis. Modeling details of the steel frame, the reinforced concrete (RC) slab, the interactions between the RC slab and the frame beams, and the associated constitutive relationships for cyclic loading are presented. A composite frame previously tested by the writers is analyzed using the proposed FE model. Good correlation is observed between the experimental and analytical hysteresis curves up to rotation amplitude of 0.04 rad. One of the notable observations during the loading to large rotations is the fracture at steel beam ends. To simulate such behavior, a simplified fractured steel connection model is introduced. The proposed nonlinear model is found to be capable of capturing the fracture behavior of beam ends to an acceptable accuracy.