Analysis of framed tube structures of arbitrary sections

Abstract

An efficient three-dimensional analysis of framed tube structures with arbitrary cross sections, but of uniform panel properties, is presented. It is based on the finite strip method (FSM) and involves transforming the discrete structure into an elastically equivalent orthotropic tube. Unlike the usual FSM, the different modes in the stiffness matrix given here are uncoupled. This results in a much smaller matrix, and, consequently, the analysis of the highly redundant framed tube structures can be conveniently and economically handled on a microcomputer. To assess the accuracy of the proposed formulation, two unperforated tubes of rectangular and triangular cross sections are analyzed, and the results are found to be in good agreement with solutions obtained using the finite element method (FEM). As an application, a 30-story framed tube structure is analyzed. Comparison with solutions from a three-dimensional finite element program shows good agreement, with the overall stiffness reasonably well predicted.