Seismic Damage Assessment Of The Existing Building Based On The Nonlinear Analysis

Earthquakes are one of the major natural disasters which human beings face, our country is located in interchange central Pacific seismic zone and the Eurasian seismic belt,having always the frequent earthquake activity. However,at the current level of science and technology, we still can’t to predict earthquakes of time, place and strength accurately.Therefore, we can only take certain defense to reduce hurt brought to us by earthquakes.Where,housing construction as an important living and working space, keep good performance under earthquake, Which will be great way to reduce casualties.Earthquake damage assessment of existing buildings was just based on such a purpose.when we use certain ways to have a clear understanding and evaluation about building work performance,the basis for the maintenance and reinforcement can be provided,meanwhile,the structure design can be also guided. Further working and decision material can be provided for relevant competent department by large range of the earthquake damage assessment.This paper utilize seismological bureau of anhui province to seismic fortification special investigation in northeast of anhui province as the background.Taking a multi-storey RC frame structure for example, the nonlinear static elasto-plastic analysis (Pushover) and gradually increment dynamic time history analysis (IDA) numerical simulation method are used to simulate.Finally,the performance parameters of structure can be gained, and comparison with experience method.Thus, this paper expounds the earthquake damage assessment process of the frame structure.In the during of nonlinear static analysis, according to the structure characteristics, four kinds of analysis conditions are choiced. At last,their Pushover curves are gained and earthquake damages are evaluated comprehensively by the capacity spectrum method and combining with formation of a plastic hinge.In the during of Dynamic analysis, two practical seismic records and a synthetic wave are selected, and then gradually increase PGA of each wave,finally,a total of24analysis condition can be formed. Structure displacement response of each conditions are gotten by the direct integral method,and seismic demand can be judged comprehensively, according to the layer displacement Angle and formation of a plastic hinge. Analysis shows that,there are some differences of the result between nonlinear method and experience method to the existing building evaluation.The former dependent on the correctness of the model and analysis parameters settings,but can clearly see the whole process of change of the structural performance and help us to make reasonable judgments;the latter is the basis of experience in considering the influence of many factors,speaking from the big range,it rather has evaluation accuracy.In addition, the stiffness of the stairs have a greater impact on the structure of the overall performance.