Seismic Performance Analysis Of Base-isolated Structure Based On Energy

As a kind of efficient and convenient technique to reduce the earthquake disaster, the base-isolated technology has been widely applied into modern structure. Although the base isolation structure has good cushion effect under earthquake action, the supper structure may enter nonlinear state which can cause different damages and the isolation bearings may generate a large deformation which can lead to the whole structure’s collapse. But the current, the isolated structural damage data under real earthquake is relatively scarce. Therefore, in order to deeply understand the seismic performance of base-isolated structure under earthquake action, the most direct and effective way is the theoretical analysis method. The story drift and maximum displacement of the isolation layer are used as the indicators to study seismic performance in the existing research, but ignoring the cumulative damage(i.e., energy dissipation), which may not reflect the real damage under the earthquake action.In this paper, taking the base-isolated of RC frame structure for research object, starting from the energy point of view, damage analysis is carried out for the supper structure considering the deformation and energy of two-parameter damage model. Further-more, the fragility analysis is also worked out for the supper structure using the maximum damage index of the floor. The specific work is as follows:(1) From the energy point of view, the two finite element models, the baseisolated structure and non-isolated structure structure, are built according to the Nonlinear Finite Element software Perform3 D. Then, using the dynamic time history method to calculate two models response,compared with the rules of seismic energy input, distribution and dissipation when these structures suffered frequent, fortification and rare earthquake with different properties.(2) Two-parameter damage models considering the deformation and energy were intruduced by the levels of component and floor. Dynamic elastic plastic time history analysis of the base-isolated structure is carried out by the Nonlinear Finite Element software Perform3 D. The component damage index of the supper structure is calculated by using the corresponding component damage model, and the damage index of each floor is also obtained. The floor damage index is used to evaluate the various damages of the base-isolated structure when it suffered fortification, rare and super earthquake earthquake action with different properties.(3) Selecting the ground motion with different characteristics, the incremental dynamic analysis method is used to anlyze the dynamic nonlinear behavior of the base-isolated structure. The maximum floor damage index of the supper structure are obtained, and the seismic fragility curves of the base-isolated RC frame structure under earthquake with different characteristics are established after statistical analysis of the damage data points.