Research On The Capacity Spectrum Method Of High-rise Buildings And Its Application

In order to design such a structure that it is capable of sustaining the behavior required when subjected to various earthquake actions, the code for seismic design of buildings has improved the requirement for checking calculation of elastic-plastic deformation; the calculation of elastic-plastic deformation for structures can be simplified through the static elastic-plastic analysis, in which the more widely used are the Pushover analysis method and the capacity spectrum method. However, owing to the complexity of the calculation of elastic-plastic deformation for structures, some problems required to be pressingly solved exist at present in the Pushover analysis method and the capacity spectrum method, so with respect to the Pushover analysis method, this article made some modifications and put forward several suggestions for problems present in the capacity spectrum method.Firstly, in this paper the development of static elastic-plastic analysis method and the present situation of domestic-overseas researches of this method were discussed; several representative analysis methods were introduced, such as the Pushover analysis method, the capacity spectrum method, the influencing coefficient method of displacement, and N2 method, etc; the fundamental concepts and principles of the Pushover analysis and ATC-40 capacity spectrum method were emphatically dealt with; three existing problems were pointed out during solving process of the capacity spectrum for structures: how to consider the influence of high order modal, which pattern of lateral load should be selected, and how to determine target displacement, etc. For the sake of solution of problems described above, this paper addressed the numbers of modal which play an essential influence on the seismic response and then can be determined on the basis of modal participation weight, so as to consider the influence of high order modal on structural performance; Besides, this paper performed an analysis on several lateral load patterns which are commonly employed at present, and the results indicated that the results obtained by modal load are superior to those by other load patterns. Subsequently, the procedures and assumptions of modal Pushover analysis (MPA) were explored, and such problems were pointed out as the deficiency in considering rigidity variation of structures after yield due to those assumptions; the selection of modal vector was modified, and the lateral load pattern of two phases was advanced; meanwhile, the methods for determination of target displacement were also revised. Next, this paper utilized the modified elastic-plastic analysis method proposed here, through finite element software SAP2000, performed a static elastic-plastic analysis on the calculation model for a 15-story RC frame structure, and compared the analysis results with results obtained by dynamic time history analysis, which verified reliability and applicability of the method presented in this paper. The research results revealed that the adoption of static elastic-plastic analysis method in this paper to conduct a Pushover analysis on structures can comparatively simulate structural response to earthquake, and it possesses desirable advantages of easy operation and high-accuracy calculation, etc. Finally, the application of the static elastic-plastic analysis method in irregular structures and the second order effect on structures were investigated.