Numerical Analysis Of Mechanical Performance Of Precast Concrete Coupled Shear Wall Base-isolated Structure

In recent years,the state vigorously promotes and develops prefabricated buildings.At present,shear wall structure system is mostly used in domestic residential high-rise buildings.Therefore,prefabricated concrete shear wall structure has been rapidly popularized and applied in the field of construction engineering.The natural vibration period of the structures will extend when applying the base isolation technology to it,thus,the structural response of the building under the horizontal earthquake will be reduced,and the influence of the earthquake on the structure will be weakened.The application of seismic isolation technology to precast concrete shear wall structure is an effective means to improve the structural seismic performance.On the basis of the low cycle level load test of precast concrete coupled shear wall base-isolated structures,a refined model is firstly proposed to simulate the precast concrete coupled shear wall base-isolated structures by using the finite element analysis software ABAQUS,then,the mechanical performance of precast concrete coupled shear wall base-isolated structures and cast concrete coupled shear wall base-isolated structures are compared and studied.On this basis,the impact of single or double sleeve connection,span-depth ratio of the coupling beam and the stiffness of isolation layer on the mechanical performance of precast concrete coupled shear wall base-isolated structures are studied,the main conclusions are summarized as follows:(1)The skeleton curves,stiffness degradation and failure mode of precast base-isolated structures are almost same as the cast base-isolated structures.However,the opening angle of joint connections at the bottom three-story shear walls in the base-isolated precast structures became more obvious.Moreover,the yielding number of longitudinal reinforcement in the bottom three shear walls of precast base-isolated structures were less than that in cast base-isolated structures after the structure reached their ultimate strength.The lateral displacement caused by the joint opening angle occupied 10% of the lateral displacement of superstructure in precast base-isolated structures.In terms of the proportion of horizontal displacement caused by the rotation of the isolation layer,the proportion of the cast base-isolated structures is higher than that of the precast base-isolated structures.(2)When the reinforcement ratio of the cross section is basically the same,the bearing capacity of the precast base-isolated structures with single sleeve is lower than that of precast base-isolated structures with double sleeves.The opening angle of joint connections in the base-isolated precast structures with single sleeve became more obvious,the yielding number of longitudinal reinforcement in the bottom three shear walls of precast base-isolated structures with single sleeve were less than that in precast base-isolated structures with double sleeves after the structure reached their ultimate strength.The lateral displacement caused by the joint opening angle occupied the lateral displacement of superstructure in precast base-isolated structure with single sleeve were 5%～15% higher than that of the precast base-isolated structure with double sleeves,and the rotation of the isolation layer of the precast base-isolated structure with double sleeves is larger than that of precast base-isolated structure with single sleeve.(3)The coupling degree of the shear wall on both sides of the coupling beams will increase with the decrease of the span-height ratio of the coupling beams,thus,the ultimate bearing capacity and inter-story shear force of the precast base-isolated structure are improved,the damage of the coupling beam and both sides of the shear wall is more serious on each floor.The longitudinal reinforcement stress of the shear wall increases,and the joint angle of the precast shear wall is more obvious on bottom several floors,meanwhile,the vertical deformation of the isolation layer is more uneven,and the rotation of the isolation layer shows a downward trend.(4)With the decrease of the specification of LRB isolation bearing,the vertical stiffness of the isolation layer decreases,thus,the local bending failure is more likely to occur at the end of the compression side of the transfer beam,which will aggravate the plastic damage of the superstructure,resulting in the decrease of the bearing capacity of the precast base-isolated structures.In addition,the reinforcement stress in the shear walls and the joint angle between the bottom shear wall and transfer beam in isolation layer will increase with the decrease of the stiffness of the isolation layer.The decreasing vertical stiffness of the isolation layer will lead to more uneven vertical deformation of the isolation layer,and the rotation angle of the isolation layer shows an upward trend.