Simplified nonlinear response simulation of composite steel–concrete beams and CFST columns

A computationally efficient macromodeling scheme to simulate the nonlinear behavior of composite structural connections consisting of steel–concrete composite beams and concrete-filled steel tubular (CFST) columns is investigated. The model proposed for composite beams, validated using four full scale composite beam tests, 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. The proposed methodology is shown to be viable for nonlinear analysis of composite structures wherein the modeling strategies are amenable to available features in modern nonlinear structural analysis software.