Analysis of the Three-stories Unsymmetrical Outrigger-braced Structure

Abstract

This project is to study the optimum locations of the outriggers of an outrigger-braced structure with unsymmetrical three-stories. In this project, the governing equations about the compatibility of columns’ axial deformation for the unsymmetrical three-stories outrigger-braced structure are derived, which is based on the method proposed by Er and Iu (2009). Itis an improved version of the method proposed by Smith and Salim (1981) for analyzing the symmetrical outrigger-braced structures. The governing equations about the axial forces in the columns of the three-stories unsymmetrical outrage-braced structures are formulated. Some non-dimensional parameters are introduced when formulating the governing equations about the axial forces in the columns. They can reduce the complexity of the governing equations and more importantly reflect the behavior of the structures in various cases in general. Based on the objective that the top drift of the structure is minimized, the governing equations of the optimum locations of the outrages of the threestories unsymmetrical outrages-braced structures are formulated. Based on the derived governing equations, a computer program is written for the numerical analysis in software Matlab. The influences of the structural parameters on the optimum locations of the structure are studied numerically. It is found through numerical analyses that the optimum outrage locations are mainly influenced by the un-symmetry of the structure. The stiffness of the shear wall core, outrigger and column also influences the optimum locations of outrages. The numerical results are presented with figures under different parameter values and could be referenced in the design of three-stories unsymmetrical outrigger-braced structures.