The Influence Of Upper Structure And Isolation Layer Stiffness Ratio On The Performance Of Vibration Isolation

In recent years, earthquakes have been happening more and more often in China, bring huge causalities and property loss. Among the various seismic method,Base insolation becomes the research focus in the seismic field due to its clear definition and outstanding damping effect, which is achieved through a small horizontal stiffness of isolation layer. Thus it is particularly important to study the stiffness of isolation layer, the effects of ration of superstructure lateral stiffness and stiffness of isolation layer on damping effect.This paper first proposed the concept of stiffness ratio, i.e., ration of superstructure lateral stiffness and stiffness of isolation layer, after which two measurements of stiffness ratio are simply introduced. Then, the paper conducts the stiffness ratio test by using steel asphalt isolation pier as isolation layer and steel frame model as the superstructure. Shaking table test on two layers and three layers steel frame model are made in the laboratory to measure the ration of steel frame lateral stiffness and stiffness of isolation layer under different working condition through increasing steel bracing to change steel frame stiffness and through changing the depth to width ration of the steel frame. Also, the steel frame under different working condition is tested in the vibration table to research the dynamic characteristics and damping effect of steel frame in different stiffness ration, which is then compared with the damping effect in different depth to width ration.Through analyzing the vibration testing results of steel frame, it is discovered that the stiffness ration exerts significant effects on the damping effect. The larger the stiffness ratio is, the smaller the relative displacement and isolation coefficient will be, in result, the better the damping effect will be. Through considering the relationship between isolation coefficient and stiffness ratio, the paper analyzed that in order to exert the best damping effect of isolation coefficient, there exists a minimum limit value for stiffness ratio. Meanwhile, it has been discovered that comparing with depth to width ratio, stiffness ration has a more significant damping effect through data comparison and analysis.