Experimental Study on Failure Mechanism of RC Frame Structures Based on Performance Design Method

To verify the rationality, reliability and fault tolerance of the “two-level and two-stage” seismic performance-based design method of Guangdong standard DBJ/T 15-92—2021 “Technical specification for concrete structures of high-rise buildings”, this study designed two batches of 1∶4 scale plane RC frame structure specimens with the same seismic structure grade of first-level, second-level and third-level. During loading, iron counterweights were arranged on each floor to simulate the distributed load, and the influence of floor and floor load on the failure mechanism of frame structure was considered. The test adopted displacement-controlled single-point loading. The loading point is located at the elevation of the three-story floor beam. Before the longitudinal reinforcement of the column reaches the yield strain, it is single-cycle loading, and after the yield, it is three-cycle loading. Through the pseudo-static test, the seismic failure mode and failure mechanism of the structure were investigated, and the evolution law of seismic performance indexes such as hysteresis curves, ductility, stiffness and energy dissipation was analyzed. The test results show that the plastic hinge development paths of the specimen damage are basically the same, which conforms to the failure mechanism of the plastic hinge ductility mechanism at the beam end. The specimen has no obvious shear failure characteristics, and the bearing capacity utilization coefficient ξ can meet the seismic design requirements of “strong shear and weak bending”. The hysteresis curves of the six frame structure specimens are full, and the seismic ductility coefficient ranges from 4.36 to 6.10. The maximum value range of equivalent viscous damping coefficient is 0.125~0.165, which shows good seismic energy dissipation performance. The floor slab improves the stiffness and bearing capacity of the frame beam, which has a significant impact on the seismic failure mechanism of the specimen. The specimen maintains the seismic failure characteristics of “strong column and weak beam”, and the component importance coefficient η can ensure the seismic design requirements of “strong column and weak beam”. The failure characteristics of the specimens are random, but the overall regularity of the failure mechanism is strong, and the gradient characteristics of the specimens with different seismic structural grades are obvious.