Restoring Force Behavior Analysis Of Steel Fiber Reinforced High-Strength Concrete Mid-Rise Shear Wall

As one of the main lateral force resisting elements of high-rise building,Reinforced concrete(RC)shear wall has been widely used in engineering practice.With the emergence of high-rise building,RC shear walls have been difficult to meet the safety needs of building structures.In order to improve the bearing capacity and reduce the structural weight,high-strength concrete is widely used in shear walls.However,due to the high brittleness of high-strength concrete,and its application reduces the ductility and energy dissipation of shear walls.To improve the seismic performance of high-strength concrete shear wall,is an effective method to solve the key problems of aseismic design of high-rise building.In this study,high-strength concrete is used as the wall,and the concrete filled steel tube(CFST)columns is used as the restraining member to form the steel fiber reinforced high strength concrete(SFRHSC)shear walls with CFST columns.The seismic behavior of the new shear wall composite structure is studied by low-cycle repeated load test.The main contents are as follows:(1)Crack development and distribution,failure characteristic,the load,displacement,and energy dissipation of various characteristic states of shear wall specimens were studied through the low-cycle repeated tests of five(SFRHSC)shear walls with(CFST)columns and one(RC)shear wall.The results showed that steel fiber can inhibit the generation and development of cracks,and improve the seismic performance of RC shear wall;The existence of the CFST columns have a good strengthening effect on the bearing capacity of shear wall specimens;The bearing capacity of shear wall specimens increases slightly with the increase of axial compression ratio.(2)Based on the test results of five(SFRHSC)shear wall specimens with(CFST)columns,the effects of steel fiber volume fraction and axial compression ratio on the flexural capacity of the steel tube were studied.The calculation method of the flexural capacity of the(SFRHSC)shear wall with(CFST)columns was established.The method is applied to calculate the bending capacity of 13 shear wall specimens in this paper and related literature.The results show that the calculated results agree well with the experimental results.(3)The effects of steel fiber volume fraction and axial compression ratio on the restoring force performance of shear wall members are discussed.A four-fold linear skeleton curve model with cracking point,yield point,peak point and ultimate failure point was established.And the calculation method of load and displacement at the feature points were developed.Combined with the test results,the corresponding unloading stiffness calculation method and hysteresis rule have been proposed,and the restoring force calculation model based on stiffness degradation was applied to the(SFRHSC)shear wall with(CFST)columns.