Seismic Behavior of Rectangular High-Strength Concrete-Filled Steel Tube Frame Structure

In order to study the failure mechanism and seismic performance of rectangular high-strength concrete-filled steel tube (RHCFT) frames, the cyclic loading test as well as the finite element (FE) analysis was conducted on a single-span and two-story RHCFT frame. During the test, the formation process of plastic hinge in the specimen including the location, sequence and degree of plastic development of the plastic hinge was investigated to study the failure mechanism, and thus the failure mode of the specimen. According to the hysteretic curves and backbone curves from the experiment, the seismic performance of the RHCFT frame, including the bearing capacity, the deformation ability, the energy dissipation capacity as well as the strength and stiffness degradation, was examined. On this basis, the FE analysis model of the RHCFT frame specimen was created using Perform-3D. The effects of the axial compression ratio, the steel yield strength, and the lateral load pattern on the seismic performance of the structure were examined. The results show the RHCFT frame demonstrates a strong column and weak beam failure mode, and has the characteristics of high bearing capacity, deformation capacity, and energy dissipation capacity. The average peak load of the specimen is 1.68 times higher than the yield load. The maximum inter-story drift ratios of the top and bottom stories are 1/30 and 1/27, respectively, which exceed 66.7% and 85.2% of the limit specified in the specification. The ductility coefficients exceed the prescribed limit by 58.5% and 60.0% respectively. The axial compression ratio has a significant effect on the seismic performance of the structure. When the axial pressure ratio is greater than 0.6, the bearing capacity and deformation capacity of the structure decrease drastically. The lateral load pattern have a great influence on the bearing capacity of the structure. The load capacity of the structure is the largest under uniform loading pattern, the smallest under vertex loading mode, and the inverted triangle loading pattern is between them. The research results can provide reference for the seismic design of rectangular high-strength concrete-filled steel tubular frame structures.