The Research On Improved Modal Pushover Method Considering Higher Mode Effects

At present, the nonlinear stastic pushover analysis method for structural seismic design is apractical analysis method. The method gets more and more attention of scholars at home andabroad, how to select the right structure seismic analysis and design method has been widespreadconcern in the field of earthquake engineering. In recent years, many people research on thetraditional pushover analysis and try to improve the method, with a view to the application of themethod to get further promotion, and so the range of application of further expansion.This paper first introduces the research background, purpose and significance, the staticelastoplastic analysis method in recent years, the development and research status at home andabroad, expounds the static elastic-plastic method the basic theory, and introduces the staticelastoplastic analysis method advantages and disadvantages. This paper discusses several typicalpushover analysis method, as well as several lateral load pattern, on this foundation in high risebuilding structure pushover analysis faced by high mode effects, the number of effective modeselection, lateral load pattern and the modal analysis results of the combination of such problemsresearch.Although pushover is a simplified method of calculation, it can be considered in thestructure of plastic stage of redistribution of internal force of objective advantages, in themajority of cases also can draw ratio nonlinear time-history analysis more important information,to be able to structure subjected to earthquake comprehensive performance evaluation. However,the pushover analysis method itself exists some defects in theory, only applies to the structuralnatural period is very small and the first vibration mode of the earthquake response of thestructure to make reasonable and correct evaluation, especially for high mode is significantlyaffected by the high-level structure, evaluation for the presence of certain error, sometimes evenwrong results. To overcome the shortcomings and disadvantages of pushover analysis procedure,this paper based on the modal pushover analysis to make some improvements on this procedure.For the standard of the dynamic time-history analysis results, respectively analysis for the8layer,12layer,18layer frame structures by improved modal pushover procedure, and comparethe calculation results. The method for the evaluation of structure under strong earthquake,structural floor displacement, story shear force analysis and dynamic time-history analysismethod is quite close, it proves that the improved multi-modal pushover analysis method can beused to estimate the overall and local structure elastoplastic deformation, and can obtain theimproved mode pushover analysis method over the traditional pushover analysis method formore accurate response of tall building structures under rare earthquake actual performance,which showed that improved multi-mode pushover analysis method is feasible, accurate, for thestatic elasto plastic analysis method provide the basis for further study and improve.