Research on the collapse-resistant performance of composite beam–column substructures using multi-scale models

Abstract In this study, the collapse-resistant performance of two, one-third scale composite beam–column substructures, with bolt and welded (WUF) connections and cover plate reinforced (WUFG) connections, were investigated by performing quasi-static tests. The experimental results demonstrated that the cover plate of the WUFG connections contributes to an increased displacement and bearing capacity in comparison with that of the WUF connections. Additionally, in comparison with the corresponding steel substructures, the maximum bearing capacities of the WUF and WUFG increased by approximately 18.0% and 19.9%, respectively. Multi-scale modeling method, which combined different types of elements with a reasonable connection, using the principle of displacement consistency, was calibrated by the experimental results. The results revealed that multi-scale models not only ensured the accuracy of the model calculation results, but also significantly improved the calculation efficiency. Based on the validated models, the influence of the surrounding members on the collapse-resistant performance of the composite beam–column substructure was analyzed. The results indicated that the axial constraint provided by the surrounding members demonstrated a greater impact on the collapse-resistant performance of the beam–column substructures in a certain range. Moreover, the multi-scale models were further extended to study the effect of important parameters on the collapse-resistant performance of the beam–column substructures, including the beam height, the beam span, the boundary condition, and the outermost column section, after which suitable ranges of these parameters were suggested.