| The prefabricated concrete frame-brace shear wall system[1]is a new kind of fabricated system with independent intellectual property rights which consists of shear walls and frame-brace walls according to design.In this system,the edge regions of frame-brace walls are connected vertically,but the other regions are not connected.The unconnected regions are filled with mortar.Through the treatment of boundary conditions,the mechanical mechanism of this system is equivalent to a frame collaborative with brace and there can be some circle holes in the walls at the same time.This system has a series of advantages of simple stress,clear force transmission,small connected regions,fast construction,short construction period,light walls,small earthquake action.In this paper,the seismic performance of frame-brace walls are simulated with the finite element software ABAQUS.Choose brace angle,hole ratio and axial compression ratio as the parameters,two kinds of brace angles are 30°,45°,60°,three holes ratios are 0,20%,40%,three kinds of axial compression ratios are 0.2,0.3,0.4.By establishing finite element models and select reasonable parameters,simulate the frame-brace walls under the vertical load and horizontal low cyclic action.The damage form,bearing capacity,deformation capacity of frame-brace walls with different brace angels,hole ratios,axial compression ratios are obtained,and the influence laws on seismic performance,especially seismic bearing capacity of frame-brace walls of brace angels,hole ratios,axial compression ratios are given at the same time,and put forward the shear capacity calculation formulation of frame-brace walls.The conclusions are below,1,The damage forms of frame-brace wall specimens are basic same,the concretes of edge regions first crack,cracks extent in the diagonal direction,vertical steels of the edge regions first yield,the stress transfer in the diagonal direction.The ductility of specimens with 30 degree brace is poor,and the damage forms are near to shear damage.The ductility of specimens with45 and 60 degree brace is good,and the damage forms are bend and shear damage.Therefore,the frame-brace walls with 45 degree and 60 degree can be used in the practical engineering,the frame-brace walls with degree no more than 30 can be used with the method of adding edge regions in the span;2,The bearing capacity decreases,the limit displacement increases and the initial stiffness decreases when the oblique angle is from 30 degree to 60 degree,and the frame brace walls with oblique angle of 45 degree have better ductility;3,The single span frame-brace walls with hole rate of 20%and 40%compared with single span frame-brace walls without holes,the bearing capacity decreases and the ultimate displacement increases with the increasing of the holes and the ductility coefficient and viscous damping coefficient increase;4,Along with the axial compression ratio of the single span specimens increased from 0.2to 0.3 and 0.2,the bearing capacity of the single span specimen and the initial stiffness increase,and the ductility of the single span specimens,and the limit displacement reduce with the increase of axial compression ratios;5,Equate the frame-brace wall to frame and brace and put forward the proposal capacity calculation formulation of frame-brace walls with horizontal earthquake action:And point out the equivalent influence range parameters of frame-brace wall with 30 degree,45degree and 60 degree.In the process of finite element simulation,one key issue is how to simulate the bond-slip of steel and concrete for the reinforced concrete member.In this paper,the bond-slip between steel and concrete is defined by means of tensile reinforcement and the crack of concrete is defined by damage.The hysteresis curves are very ideal and the conclusions are given by the results of preliminary exploration.How to simulate more accurately needs further research,and more factors need to be considered to modify the shear bearing capacity formulation of frame-brace wall. |
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