Nonlinear Mechanical Behaviors for System of Bearing on the Top of First Story Column

Abstract

According to the system of bearing on the top of first story column, the mathematical model of isolation system based on geometric nonlinear is investigated by using Hamilton's principle. The natural frequency of the system is investigated, and the effects of axial pressure and difference column size to the isolation system in seismic response are discussed. The isolation system dynamics model based on geometric nonlinear is established considering the cross section rotated and the influence of the shear deformation and axial pressure. The differential quadrature element method is employed for discrete processing on governing equations and boundary conditions. The natural frequency and seismic response of isolation system are solved numerically. Results show that: the axial force will reduce the lower order natural frequencies significantly. With increase of slenderness ratio of cantilever column, stiffness degradation of isolation system decreases, lateral displacement of the top of cantilever column increases, which seriously influences the stability of the isolation system and decrease the security of isolated structure, finally.