Pushover Analysis-based Seismic Structural Reliability Analysis, Considering The Intermediate State

Earthquake is a kind of natural disaster with strong destructive power and may do serious harm to human beings when it abruptly occurs. Strong earthquake will cause great loss of life and property. The main and direct reason is the building structure in the felt area of earthquake does not have the capacity to resist the seismic action, with the result of that the building structure is serious damaged, even collapse. The reliability analysis of building structure is the important measure to assure building user's life and property security. For the building structure which has been used for some years, it has great significance to predict the residual service life of it, under a certain security probability or failure probability.This study based on the principle that structures should have three work states—safety state, intermediate state and failure state. In this paper, we explored the methods of reliability analytical approach and residual service life prediction of aseismic structure with intermediate state, by the means of theory research, numerical analysis, finite element analysis and practical engineering application.Firstly, according to the results of seismic hazard analysis for 45 cities and towns in Northern, North-Western, South-Western Regions of China, and the conclusion that the probabilistic distribution model of seismic intensity fits Extreme Value Type III, meanwhile the probabilistic distribution models of peak ground acceleration and basic structural shear in the design reference period fits Extreme Value Type II, we worked out the related parameters for each probabilistic distribution model when the design reference periods were 10, 20, ..., 100 years, respectively. These probabilistic distribution models and related parameters provide preconditions for reliability analysis and residual service life prediction of aseismic structure. Also, they have some reference values for seismic design, especially when the design reference period of the project is not 50 years.Secondly, we established a method to determine the upper limit and lower limit of structural resistance by pushover analysis.Then, according to the method of reliability analysis for three levels of fortification of aseismic structures and the probabilistic distribution models of seismic actions with the related parameters discussed before, we established a method of reliability analysis of aseismic building structure with intermediate state and based on pushover analysis, as well as time variation of structural resistance was considered.Finally, we put forward a simple method to predict the residual service life of aseismic structures. It is a contrary process of the reliability analysis previously mentioned.