| “Very rare ground motion”has been added to “Seismic ground motion papameters zonation map of China”implemented from June,1,2016.RC frame structure is a kind of main structural system widely used in China,but it suffers from earthquakes seriously because of its poor seismic performance.In order to reveals profoundly the seismic performance and rules of the RC frame structure under multi-level earthquakes,provide a more optimized structutal design and a more targeted reinforcements scheme and promote the development of performance-based seismic design theory,the seismic performance analysis and evaluation of the RC frame structure under multi-level earthquakes,including very rare earthquak,have theoretical significance and engineering value.Based on the relevant provisons on performance-based seismic design in “Code for seismic design of buildings of China” and referring to American code,this paper establishes “frequent,basic,rare,very rare”four seismic fortification levels,“basically intact,slight damage,medium damage,serious damage”four structural performance levels and“special,emphasis,standard and moderation”fours seismic fortification targets.The specific implementation steps of evaluating the seismic performance of RC frame structure is proposed by using the inter-story ratio as the quantifired index of seismic performance of overall structure and using the plastic rotation angle of beam and column as the quantifired index of seismic performance of components.pushover analysis and elastic-plastic dynamic time history analysis are adopted to evaluate the seismic performance of a multistory RC frame structure and a high-rise RC frame structure under four level earthquakes.The study show that the evaluation result of pushover analysis is consistent with elastic-plastic dynamic time history analysis.Considering workload and precision requirement of seismic performance evaluation,Pushover analysis is recommended.According to the evolution of plastic hinge,the pushover curve can be divided into four phases:“elastic phase,quantity of plastic hinge of beam development phase,plastic degree of plastic hinge of beam development phase and plastic hinge of column development phase”.Concrete strength,steel bar strength,reinforcement ratios of beam,reinforcement ratios of column,axial compression ratio and rigidity-to-gravity are used as variables to analys the seismic performance of two structures.Based on the influence rules on seismic performance of the RC frame structure in four phases by these factors,the method of improving the seismic performance of the structure is put forward. |
