Study On The Residual Displacement Of MDOF System

Structure will remain residual displacement after earthquake for the adoption of the ductility of structure seismic design,large residual displacement will bring technical difficulties and huge cost to the repair of the structure after earthquake,and the structures even have to be dismantled,so,the research for residual displacement of structure under strong earthquake has important theoretical significance and practical value.In this paper,the residual inter-story displacement is calculated for a family of buildings having 5,10,20 stories respectively by the way of elastic-plastic time history analyses using 60 earthquake records with no near fault effect according to NEHRP.The effects are studied,and a simplified calculation formula is established,finally,the residual inter-story displacement is analyzed by wavelet.The main research contents and results are as follows:(1)MATLAB software is used to compile the nonlinear multidegree-freedom system seismic response calculation program.(2)The effects of floor number,post yielding stiffness coefficient,site type,yield strength coefficient and weak degree on the residual inter-story displacement are studied.The result shows that in the case of "uniform" buildings,the residual displacement between the bottom layers is the largest,and for the buildings that are not "uniform",the "weak" layer has the largest residual displacement between layers;on the whole,the smaller the strength of the structure,The larger the coefficient,the more the number of layers,the greater the degree of nonuniformity,the greater the maximum residual displacement between the layers;for the yield stiffness coefficient of the larger system,by increasing the yield stiffness coefficient to reduce the maximum residual displacement between the effect of Obviously,when the site class is B or C,if the influence of the site category is neglected,the value of the residual displacement between the layers is usually overestimated.When the site class is D or E,if the influence of the site category is neglected,The value of residual displacement between layers is usually underestimated.(3)The wavelet components which dominate the residual inter-story displacement are the components with the period range contains the structure period,and the low frequencies near the fundamental frequencies of the frame also has big influence,which can become the control component when the peak is large enough,the others’ are smaller sharply.