The Study On The Maximum Suitable Height Of Frame-shear Wall Structure In Pushover Analysis

As a simplified method of evaluating structural seismic performance,nonlinear static analysis method is gradually used widely and has been added to Chinese new code for seismic design of buildings.Its applicability has become an important research direction on account of its deficiency of theoretical hypothesis.Firstly,a simplified model was build.In order to make complex finite element analysis easy to calculate and employ structural response of simplified model under seismic action to simulate that of actual structure,dead load,live load of roofs and floors,dead load of filled walls were transferred to concentrated load on columns and uniformly distributed load on beams and shear walls.Based on SAP2000,a finite element analysis software,Pushover analysis and elastic-plastic time-history analysis were conducted of five simplified models which have different height.When conducting pushover analysis,three kinds of load pattern that comes with the software were selected(equal accelerated load pattern,modal load pattern and normalized modal quality load pattern)and additional effect caused by lateral drift under dead load(called P-? for short).Curve of base shear-peak displacement,inter-story displacement angle on performance point,inter-story shear and graph of plastic hinge development were gained.Structural weak parts and destruction were found.Elastic-plastic time-history analysis was conducted under two natural seismic waves and a man-made wave which were appropriate for second site,structural responses under these two methods were compared and appropriate height of pushover method on high-rise buildings was evaluated.In order to testify the appropriate height that comes from the simplified model,three-dimensional high-rise building was established and its seismic performance was analyzed by pushover analysis and elastic-plastic time-history analysis.Conclusion shows that: with the increase of structural height,the errors between results gained by pushover analysis and that by time-history analysis,such as inter-story displacement,inter-story displacement angle,inter-story shear and plastic hinge development,were increased gradually.For class II on the field of reinforced concrete frame-shear wall structure construction,evaluation of structural response under seismic load by pushover analysis was accurate for reinforcement concrete high-rises structure which height does reach about 115.5 meter.The accuracy of this method were declined obviously when buildings height exceed 130 meter so that this method cannot be used to seismic analysis on that height.