Theoretical And Experimental Study Of Story Isolation Structure

The story isolation is a newly proposed isolation system, in which the flexible laminated rubber bearings are inserted between a floor and the columns that support it. The present research work of the story isolation system is at initial stage and there is not systematic and theoretical result. In this paper a six-story steel frame model is studied by ANSYS which is a numerical analysis program based on the experiment of this model to analysis the effect of the story isolation.First, the mechanism of base isolation and the mechanism of TMD are introduced respectively. Secondly, after the restoring force models of the structure and the isolation system defined, the dynamic differential equation of the isolation structure is set up based on the based isolation system. Finally, the finite element model of the story isolation structure is set up by ANSYS which is a numerical analysis program. The seismic response of story isolation structure with fixed isolation bear and changed bear are calculated under different seismic wave. The results of calculation are analyzed and compared with fixed structure. The regulations of seismic response of story isolation are summarized.The study result is listed as follow. Applied by unidirectional , bidirectional and three direction earthquake force, the story isolation system with rational lateral stiffness and damping ratio may reduce the seismic response of the structure effectively .The total seismic response of the structure when multidirectional earthquake action is applied is greater than the seismic response of the structure applied by unidirectional action, but the components in every direction is the same. The vertical force of the bearing when it is applied by multidirectional earthquake motion increases obviously. The analysis results show that themechanism of story isolation structure has been significantly influenced by the location of the isolation layer. When the location is approach to the roof of structure, its mechanism is similar to that of the Turned Mass Damper (TMD);And When the location of isolation layer is approach to the base of structure, its mechanism is similar to that of base-isolation structure. The two kinds of mechanism are very different.