Seismic Response Analyses On Story Isolation Structures

The story isolation structure is a new type of seismic isolation structure evolving from the application of base isolation technologies in engineering practices. Most of present researches on the story isolation system have only considered the horizontal seismic action and neglected the vertical seismic action. However, a lot of earthquake disasters indicate that the effect of the vertical earthquake on the structure cannot be neglected, and sometimes it may play a greater role than the horizontal earthquake. For this reason, it is very important to study compound isolation devices with both functions of horizontal and vertical isolation, and to study corresponding isolation technologies. Based on the laminated rubber bearing, in this article a compound isolation bearing composed with dished spring-laminated rubber bearing is put forward. This compound isolation bearing can isolate the energy due to the horizontal earthquake action from being transferred to the upper structure as well as can reduce the influence of the vertical earthquake on the structure, which enjoys a good prospect of application in the field of story isolation.This article first analyzed the mechanical behavior of the dished spring-laminated rubber bearing compound isolation bearing, investigated the isolation mechanism of this compound bearing, and by the adoption of story shear model for the structure, derived the dynamic time history equations of the story isolation structure with compound isolation bearing set under the action of the horizontal earthquake. Then by ignoring the coupled action between the vertical and horizontal earthquake, this article derived dynamic equations of the story isolation structure under the action of the vertical earthquake. Finally, this research took a long-span frame structure of five stories as an example, performed a time history analysis of seismic response on the long-span frame structure with the installation of dished spring-laminated rubber bearing compound isolation bearing, tested the isolation effect of this type of bearing, and discussed the corresponding the isolation mechanism and laws.The research results infer that the compound isolation bearing mentioned here has a good property of compound isolation; not only it can inhibit seismic energy transmission into the upper structure and reduce the response of the structure to the horizontal earthquake, but also it can also effectively inhibit the response of the structure to the vertical earthquake. Thus, this topic is worthy to be investigated deeply and exploited for application to the engineering practice.