Dynamic Response Analysis Of Considering The Uneven Settlement Of Collapsible Loess Foundation Of Base Isolated Structure

As a kind of effective and economic seismic method which has been applied more widely.And in the earthquakes the base isolated structure show nice seimic performances and is widely concerned, and reduced the great damage and casualties in seismic areas. But the appeared problems should to be solved in the process of using, in terms of distribution of a large number of collapsed loess in our country, uneven settlement of the foundation of the base isolated structure would cause excessive deformation, cracking, tilting and even collapsed, these problems are civil engineering construction facing of the major issues. This paper analyzes the key causes of collapsed loess foundation uneven subsidence, the influence of the isolated layer and the upper structure and isolated bearings should be timely maintenance and replacement, which not only has important theoretical significance, but also has important engineering value.Based on the limit-value requirements on framework structure settlement of Code for Design of Building Foundation, specify a variety of settlement area and settlement and by applying a displacement load make the settlement applied to structure basis. In this paper, base isolated structure for settling using the nonlinear dynamic analysis to calculate, the mian research content is as followed.(1) This paper outlines the proposed,research status and significance, and describes the status of at home and abroad isolated structure and the influence of uneven settlement of the foundation to the structure.(2) For Fast Nonlinear Analysis Method to calculate collapsed loess foundation uneven settlement caused the problems of isolated bearings settlement, and balance loads to the influence of isolated bearings settlement for the isolated structure. The results found that, bearings settlement may cause damage of bearing and structure, and the isolated bearing area of bearing stress and beam internal force has a great impact.(3) For the base isolated structure after settlement, through dynamic elasticplastic analysis. Key consideration the different of loess foundation settling area and settlement affect the performance of base isolated bearing in rare earthquake, through analysis, due to settlement occurrence will take place ahead of bearing deformation and stress overload,even making the bearing failure out of work,and found that increases of the settlement will for the influence increases of isolated bearing obviously,.(4) For the isolated structure occurred after settlement, in rare earthquake, the response on the upper structure should be emphasized. Through dynamic elasticplastic analysis found that the occurrence of settlement will make the upper structure into the elastic-plastic stage in advance, so that reduce the upper structure has reached seismic measures in addition it is found reverse ratio and the top floor displacement of the structure time history curve will increase with the increase of settlement,and the settling area of the structure is also considered.