Experimental and Numerical Studies on Seismic Behavior of Composite Frames with Initial Heavy Load Conditions

摘要

This study investigates the seismic behavior of composite frames with initial heavy load conditions. Two frame specimens consisting of square concrete-filled steel tube (CFST) columns and steel-reinforced concrete (SRC) deep beams were fabricated and poured using ordinary concrete and high-strength concrete, respectively. Thereafter, the two specimens were tested under cyclic loadings, and the failure models, hysteretic behavior, bearing capacity, ductility, and accumulated energy dissipation of the specimens were investigated in detail. The experimental results revealed that both of the specimens failed owing to the local buckling at the column ends. This kind of composite frame has good seismic performance and can be regarded as a high-ductility structure. Moreover, a finite element (FE) model was developed and verified by the experimental results. The effects of the typical parameters, such as the material strength and axial compression ratio, were studied using the FE model. The parametric study demonstrates that increasing the yield strength of the steel tube can effectively improve the ultimate bearing capacity of the composite frame and that decreasing the axial compression ratio is a valid method for improving the ductility of the structure.