NONLINEAR RESPONSES OF A BUILDING STRUCTURE TO EARTHQUAKE EXCITATION

Abstract

A simplified stick model for the nonlinear dynamic analysis of a building structure is presented. Based on the strong-column weak-beam design philosophy, similar deformation shapes for all the columns in the same storey of a building structure is assumed. Therefore, while subjected to horizontal earthquake excitation, the inflection points of beam elements of building structures are assumed at either the middle of the spans or the locations of the plastic hinges in beam elements. After stacking all the column lines of the building structure and making use of the technique of static condensation for the stiffness matrices of beam elements, the simplified stick model with intermediate rotational constraints at all the floor levels can be set up. Bilinear behavior for beam and column elements is adopted for the nonlinear analysis. The advantage of using the proposed stick model for nonlinear dynamic analysis is to slash the computational cost, since the number of the degrees of freedom for each floor level is only two and the bandwidth of the stiffness matrix for total structure system is four. Some numerical results and some comparisons with the results of DRAIN-TABS are presented in order to show the effectiveness of the simplified model, and some possible extentions of the stick model are also discussed.