Global Nonlinear Dynamic Response Analysis Of High-rise Isolation Structure

Compared with the traditional anti-seismic structure, the period of isolation structure increased. At the same time, the earthquake action are significantly reduced because of the isolating device. Therefore, it is usually assumed that the upper structure is always in the elastic, stiff or even. With the application of seismic isolation structure system in China, isolation structure are becoming increasingly complex, which are no longer confined to planar symmetry or regular structure,and the isolated structure over 100 meters has appeared. On the other hand, ultra intensity, long period, near fault pulse and other complex vibration have aroused universal concern of the nonlinear vibration response of structure. Based on these two factors, the assumption that the upper structure of the base isolation has always been in elastic must be reexamined. In recent years, some scholars have studied the seismic response of isolated structures considering the gobal nonlinear. However, it is mostly based on the definition of the macro-seismic restoring force model which is defined on the floor or member level.Through large-scale general finite element software platform(ABAQUS), the model and the method of nonlinear dynamic time history analysis for the high-rise isolation structure is explored. The differences of dynamic response is researching by considering the elastic and plastic properties of the superstructure in typical earthquake, and the necessity of the whole nonlinear analysis for seismic performance evaluation of high-rise isolation structure is explored. Moreover, the floor stress of the different assumptions of the slabs are considered. The following research work has been carried out:(1) The research status of the structural nonlinear analysis model and the complex high-rise isolated structure are summarized, also the refined nonlinear analysis model of the isolated structure is introduced.(2) The mechanical model of the isolated bearing is summarized, and the behavior of the connection unit in ABAQUS are analyzed.(3) According to the structure of a real high-rise isolated shear wall, the dynamic time history analysis of the seismic and rare earthquake are carried out by considering the elastic and plastic properties of the superstructure.(4) The effects of the different assumptions of the slabs are considered.Through the above research work, the following main conclusions are drawn:(1) When the full nonlinearities of the whole structures is taken into accounts, the seismic reduction factors decrease(2) The structural response of the elastic plastic model of the upper structure under rare earthquake is obviously increased, and moreover, the shear walls and slabs come into the plasticity actually. Therefore the assumption that the upper structure of the base isolation has always been in elastic is clearly unreasonable.(3) Considering the full nonlinearities of the whole structures, the displacement of the isolation layer decreases.(4) Shear forces and drifts of the floors that resulted from elasto-plastic slab assumption are obviously greater than that from elastic-slab assumption.(5) The response of the local nonlinearity of the bearings and the damaged plasticity of the super-structure are obvious different, so the analysis of the overall nonlinear is necessary.