Buckling And Post-buckling And Lardge Deformation Of Serial Seismic Isolation System

The base isolation technology among existing building structure control technology shows excellent performance in effectively reducing the damage resulted from the recent ground motion. In engineering practice, most isolated structures are taken up by serial seismic isolation system which is composed of multilayer electrometric bearings and cantilever column of basement. To ensure the stability of serial seismic isolation system becomes very important. The deformation of the basement cantilever column and second-order effect has negative effect on bearing capacity and reduction capacity of isolation components. The security problem of serial seismic isolation system has become focus of attention by engineers and researchers. To solve such the problem, in this paper the buckling, post buckling and large deformation of serial seismic isolation system have been studied systematically. The main work and conclusions gained are listed as follows:(1) According to the stability of laminated rubber bearing serially connected with column, which concerned engineering field, the critical load governing equation is established and investigated the influences on the stability. First, field matrix of stability of single laminated rubber bearing is established; Secondly, field matrix of the stability of laminated rubber bearing serially connected with column and the stability governing equation based on transfer matrix method are established , respectively, which avoids tedious mechanical derivation; Finally, calculated the stability of two kinds of series seismic isolation system using numerical calculation method, and investigate parameter variation of multilayer electrometric bearings influence on the stability of series seismic isolation system., some of the conclusions drawn useful for practical engineering applications.(2) According to horizontal stiffness of laminated rubber bearing serially connected with column, which concerned engineering field, the horizontal stiffness formula was established and compressive stress influence on horizontal stiffness and dynamic response of isolated structure were investigated. First, field matrix of single laminated rubber bearing was established. Secondly, field matrix of the laminated rubber bearing serially connected with column, the relation between internal force and displacement at arbitrary cross sections and state variable at end of laminated rubber bearing serially connected with column, the horizontal stiffness formula based on transfer matrix method were derived, avoiding tedious mechanical derivation. Finally, compressive stress influence on horizontal stiffness and seismic response of isolated structure were investigated. The results shows that the horizontal stiffness decrease with the rise of the compressive stress, laminated rubber bearings fixed in foundation should be adopted in near fault area.(3) To solve the stability of series seismic isolation system connected with column and coupling beam, which concerned engineering field, the critical load governing equation based on transfer matrix method was established. First, field matrix of stability on single laminated rubber bearing and point matrix of stability on coupling beam were established; Secondly, characteristic matrix of the stability on series seismic isolation system and the stability governing equation based on the characteristic matrix were established , which avoided tedious mechanical derivation; Finally, calculated the stability of two kinds of series seismic isolation system using semi-analytic method, and investigated parameters variation influence on the stability of series seismic isolation system, some of the conclusions drawn useful for practical engineering applications.(4) By using differential quadrature method, the post-buckling and large deformation of beam-column based on two different models, which one is considering trans-verse shear deformation and another without considering, is comparative analyzed. First, by accurately considering the axial extension and without considering trans-verse shear deformation in the sense of theory of Timoshenko beam, geometrically nonlinear governing equation for beam-column subjected to loads is formulated, by using differential quadrature method the post-buckling and large deformation of beam-column is analyzed. Then by accurately considering the axial extension and considering trans-verse shear deformation in the sense of theory of Timoshenko beam, geometrically nonlinear governing equation for f beam-column subjected to loads is formulated. Finally, by using differential quadrature method, the post-buckling and large deformation of beam-column is comparative analyzed.(5) The post-buckling and large deformation of laminated rubber bearings and series seismic isolation system is investigated. Taking laminated rubber bearings as an equivalent homogeneous elastomer and accurately considering the axial extension and considering trans-verse shear deformation, geometrically nonlinear governing equation for bearings subjected to loads is formulated, by using differential quadrature method, the post-buckling and large deformation of laminated rubber bearings is analyzed. For series seismic isolation system, geometrically nonlinear governing equation accurately considering the axial extension and considering trans-verse shear deformation is formulated. Because series seismic isolation system in connection position material and geometrical discontinuous, differential quadrature method can not be used. So by using differential quadrature element method, the post-buckling and large deformation of series seismic isolation system is analyzed. Through analysis on comparing with the result of pseudo-static test, it is shown that the calculated and experimental results consistent with law.