Research Of Three-Dimensional Seismic Isolation Bearing For Large-Span Structure

In this thesis, a new type of3-Dimensional seismic isolation bearing (3DGZ) is designed after studying the existing seismic isolation bearings in order to meet the seismic isolation demand in long span structures. After considering dynamic properties and seismic response characteristics of long span structures, the determina-tion method of the key parameters in the design of the bearing are suggested. Finally, the hysteretic characteristic of3DGZ is analysed by ANSYS FEM. The research results are as follows:(1) A new type of3-Dimensional seismic isolation bearing is designed, which can meet the seismic isolation demand in long span structures. The horizontal seismic isolation device is composed of Teflon plan and corrosion resistant plate, which also can provide friction damping capacity. The multiple helical springs are installed to solve the problem of horizontal reset. The vertical seismic isolation device is made of disc springs and the superimposed disc spring can dissipation seismic energy through friction. The bearing has reasonable rotation capability by using of series of disc springs. The problem of resisting lifting load is solved by constructional details.(2) The determination method of the key parameters and the steps in designing the bearing are provided. According to the size parameters of the bearing, the design method of the horizontal reset springs is suggested. After studying the features of the disc springs, the determination method of the stiffness and compound mode are summarized.(3) In order to certify the validity of finite element analysis, a seismic isolation bearing designed by predecessors is analyzed with ANSYS FEM and the analysis results are compared with the experimental results.(4) The three-dimensional seismic isolation bearing designed in this thesis is analyzed with ANSYS FEM.In order to learn about the performance of the bearing designed in this th esis, the simulated analysis had been done with the finite element software. The results have shown that the bearing can satisfy the requirement of material stren gth. The dimensions of the bearing shell is of generality, only by changing the st iffness of the spring can satisfy different seismic isolation demand. The hysteresi s behavior of the disc spring is analyzed and the errors caused by calculation as sumption are modified. Reasonable designed disc spring can provide a certain da mping capacity and the equivalent damping ratio is about10%. The value increa ses with the predeformation, but the increment is small. The shape of horizontal hysteresis loop is similar to parallelogram and its area is correlated significantly with the vertical pressure. The shape of the horizontal hysteresis loop became ir regular under dynamic vertical pressure. When the pressure attended its maximal value, the horizontal stiffness of the bearing attended its maximal value as well.