Research On The Mechanism Of Story Isolation Structure

The story isolation system is a new isolation system, the proposal of which is based on the development of base-isolation. The story isolation is 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 frame is studied by SAP2000 which is a numerical analysis program based on the experiment of this structure to analysis the effect of the story isolation, and discussed the corresponding the isolation mechanism and laws.First, the mechanism of base isolation and the mechanism of TMD are introduced respectively. Secondly, 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 SAP2000 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: The lateral stiffness of story isolation structure has a great impact to the basic period and the relative displacement of structure. The story isolation system with rational lateral stiffness may reduce the seismic response of the structure effectively. At the same time, the lateral stiffness of the structure below story isolation has a small impact to the relative displacement. The analysis results show that the mechanism 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.