Experimental And Theoretical Researches On Restoring Force Characteristics Of SRHSHPC Frame Columns

Steel reinforced high strength and high performance concrete (SRHSHPC) frame columns are the organic combination of steel and high strength and high performance concrete (HSHPC), which make full use of the advantages of steel and also effectively improve the natural brittleness of HSHPC. Consequently, the ductility of member significantly increases. With the rapid development of high-rise building, such member will have extensive application prospect in our country. However, the studies on seismic behavior and restoring force model of them are rare presently.In this paper,12 specimens of SRHSHPC frame columns are tested under low cyclic repeated loading. Meanwhile, the stress characteristics of SRHSHPC frame columns including loading process, failure patterns and crack development etc are analyzed. According to the hysteresis curve and skeleton curve of specimens obtained by tests, restoring force characteristics of SRHSHPC frame columns including the degradation characteristics of strength and rigidity, ductility and energy dissipation capacity are mainly analyzed, and the influences of axial compression ratio, steel ratio, stirrup ratio and loading path on the the seismic behaviors of SRHSHPC frame columns are discussed.The test results show that the SRHSHPC frame columns have excellent seismic behavior such as stable load-displacement hysteretic curves, plump hysteretic loop, large deformation and energy dissipation capacity.Based on the test results, the ideal trilinear skeleton curve model of frame columns considering descent segment is established, and the calculation expressions of feature points in the skeleton curve model are given. By selecting reasonable damage model, the cycle degradation indexes based on damage is proposed, which is used to describe the degradation law of specimen properties such as yield load, hardening stiffness, unloading stiffness, reloading stiffness and bearing capacity. And then, the restoring force model of SRHSHPC frame columns based on damage is established. The comparative analysis of calculation results and test results show that the proposed restoring force model can well reflect the hysteretic characteristics of SRHSHPC frame columns under repeated loading and the study results can provide theory reference for the elastic-plastic dynamic analysis of such structures.