Research On Base Isolation Structure Earthquake Response And Aseismic Reliability

Base isolation is an effective design technique against the earthquake damage to the structure. The lateral flexibility of the base isolation system increases the fundamental period of the structure and thus minimize the lateral load transferred to the superstructure during the strong earthquake.On the basis of the wide investigation of the achievement home and abroad about the base isolation, this dissertation completed the mean and variance of the displacement, velocity and acceleration induced by given earthquake base on the time-history response and stochastic FEM. Then we can figure out the Time-history reliability of bearing capacity on the assumption that distribution of structure response of earthquake referring to relation literature. The base isolation structure is safer than the ordinary structure when we compare their reliability.For the overturn problem of the base isolation structure, the limit state equation and anti-overture reliability formula of base isolation structure was deduced in the dissertation and applied to the example analysisSome parameter that influences reliability of structure was analyzed preliminarily in this dissertation. They include variance of the structural stiffness (K), damping (C) and mass (M), the ratio of height to width of the structure, damping ratio of the isolated layer, stiffness ratio of superstructure to isolated layer. The main conclusion is: the effect of variance of K, C and M towards structural reliability is small, the effect of the ration of height to width is significant towards structural anti-overturn reliability, the isolation layers' damping ratio and stiffness ratio influence the reliability of both bearing capability and anti-overturn and the latter is more significant. Some factor that influence the limit of height-to-width ratio is discussed because reliability of base isolation structure is mainly determined by height-to- width ratio.