Research On Lateral Stiffiiess Of Masonry Wall Due To Its Rotational Deformation

While the masonry structure is widely used,its seismic performance has also been widely concerned.In the existing investigation of earthquake damage,the wall limb rotation deformation of masonry structure under the action of horizontal earthquake gradually has come into the public eye.The rotational deformation of masonry wall occurs in the stage of wall cracking and entering elastoplastic stress,which has a significant effect on the lateral stiffness of masonry wall under the action of medium earthquake and large earthquake.The formula for calculating the lateral stiffness of the existing masonry structure in China is based on the analysis of bending deformation and shear deformation of the elastic stage of the wall limb,which fails to reflect the influence of the rotational deformation on the stiffness of the elastoplastic stage.The failure process under the action of earthquake and large earthquake in masonry structure is mainly in the elastoplastic stage,and the calculation of lateral stiffness and seismic distribution mechanism of elastoplastic stage members directly affect the seismic design of masonry structure.In order to improve the seismic performance of masonry structure,perfect the theory of seismic design under the action of medium earthquake and large earthquake,and better realize the seismic fortification target of "big earthquake" of masonry structure,this paper studies the theory of rotational deformation stiffness of masonry wall by means of experimental research and theoretical analysis,and the contents are as follows:(1)The quasi-static test of 4 masonry walls is carried out,the experimental phenomena such as crack development in the course of the test are summarized,the failure forms are analyzed,and the hysteresis performance,skeleton curve,stiffness degradation curve and ductility displacement angle of the test results are analyzed.The rotation phenomenon of masonry wall occurs in the process of failure,and the rotation form is related to the shape of the facade and has an effect on the stiffness of the wall.(2)on the basis of the calculation of the existing elastic stiffness,the elastic stiffness is reduced by aspect ratio,and the stiffness calculation model with the influence of rotational deformation is obtained by adjusting the coefficient alpha and beta to control the reduction amplitude respectively.By using the method of data fitting,the values of alpha and beta of rotational stiffness adjustment coefficient are obtained according to the previous test data and the test data,and the test data are used to verify.The error control of Alpha method is the same as that of the test data in 10%,βmethod,and the stiffness model proposed in this paper is feasible.(3)based on the principle of moment equilibrium of basic mechanics,the lateral stiffness of three kinds of walls,such as rectangular wall,"L" shape wall and "convex"wall,is studied in various working conditions under uniform load,triangular load and trapezoidal load.The rotational resistance lateral stiffness level of all kinds of shape walls under different working conditions is obtained,and it has a strong correlation with the vertical load action mode.