Analysis On Seismic Performance Of RC Frame-shear Wall Structure Of Tall Buildings Under The Pulse-like Mainshock-aftershock Ground Motions

Many aftershocks often occur after a main earthquake.The studies have shown that the inherent properties of the structure change evidently after the main earthquake,and the ultimate bearing capacity of the components decreases,which leads to the aftershock sequence whose magnitude is lower than the main earthquake may further cause serious incremental damage to the damaged structure and increase the collapse probability of the structure.Therefore,It is of great significance to carry on the quantitative study of the influence of the aftershock sequence on the damage increment and performance state of different structural forms on the engineering seismic design.In this paper,the time history function of the main-aftershock sequence with a pulse type aftershock after the action of two-way non-pulse main shock is selected to comparatively analyze the changes of calculated damage indexes of high-rise RC frame shear wall structures.The main research work is as follows:1.This paper summarizes the research status of high-rise RC frame shear wall structure buildings and near-fault impulse type earthquake,and the research and development process of main-aftershock sequences.Furthermore,this paper analyzes Several factors that have not considered in the existing research for supplementary analysis.2.In this paper,a high-rise concrete frame shear wall building is simplified.Firstly,the geometric model is established by using YJK software to analyze the basic information of the structure and the relevant index limits of the current code.Then,the finite element model is established in SAP2000.The rationality and accuracy of the finite element analysis model are ensured by comparing the values or trend differences of the period,base shear force and vibration mode of the two different software structural models.This paper introduces several direct integration methods commonly used in structural elasto-plastic time history analysis,and compares the accuracy and convergence of each method.3.The shear force,displacement angle and cumulative inelastic energy consumption are selected as the damage indexes.Based on the incremental dynamic analysis method,the PGA of 24 main-aftershock records with different tectonic patterns were modulated from0.05 g to 0.3g.The HHT direct integration method is used to analyze the finite element model of high-rise RC frame shear wall structure for 144 times.The damage parameter response of high-rise concrete frame shear wall structure under single pulse aftershock is studied quantitatively.The results show that the shear force,displacement angle and cumulative inelastic energy consumption of the structure increase after the additional impulse aftershock.Under the action of rare intensity main aftershock sequence,it may enter the collapse state in advance,and the results of structural calculation are different when different damage indexes and the ground motion composition mode are selected.4.Taking the logarithm of PGA as the abscissa and the logarithm of maximum inter story displacement angle as the ordinate,the statistical linear regression analysis is carried out on the elastic-plastic time history calculation results of multiple main and main-aftershock records to calculate the exceedance probability changes of each performance level of the structure after an additional pulse aftershock.The results show that the failure probability of each performance level of high-rise RC frame shear wall structure increases with the increase of the earthquake time Therefore,the impact of impulse aftershock on the structure should be considered in the seismic design.