MACROMODEL-BASED NONLINEAR SIMULATION OF STEEL-CONCRETE COMPOSITE FRAME STRUCTURES

The nonlinear responses of steel-concrete composite structures to extreme loads are numerically simulated using a macromodel-based approach. The development of the simulation model is guided by the realization that interactions between different composite components and transfer of forces through the joint are critical to predict the nonlinear behavior. The model proposed for composite beams, incorporates partial interaction between the concrete slab and the steel beam. The model proposed for CFST columns adopts fiber-based stress-strain relations that enable the consideration of strength and ductility for confined concrete and local buckling of the steel tube. The flexibility of the composite beam-to-CFST column connection is modeled as a panel zone. The validity of the simplified approach is evaluated by comparison of both overall response and local actions with those obtained from test results. It is demonstrated that the proposed methodology is viable for nonlinear analysis of composite structures wherein the modeling strategies are amenable to available features in modern nonlinear structural analysis software.