Global buckling design of multi-celled CFST walls with four simply-supported edges

Abstract

Multi-celled concrete filled steel tubular wall (MCFSTW) is an innovative shear wall member which is formed by welding multiple U-shaped cold-form steels together and filled with concrete. The global buckling performance of composite walls is of great concern, especially with the increasing wall height in engineering practice. In this research, the global buckling behavior of MCFSTWs with four simply-supported edges is studied. A refined finite element (FE) model was established and validated by comparing it with previous test results. Then, a numerical parametric study was conducted to investigate global buckling behavior influenced by various parameters including: geometrical dimensions, initial imperfection and material strengths. Based on an orthotropic plate model, an analytical study was performed to derive the theoretical formulas for predicting the elastic buckling loads of MCFSTWs with four simply-supported edges. According to FE eigenvalue buckling analysis results, the obtained theoretical formulas were further modified to fit well with the FE results, thus providing better predictions of the elastic buckling loads of MCFSTWs. Finally, a design curve in a form of φ -λn relationship was proposed on the basis of the results obtained from numerous FE models with an imperfection amplitude of w0 = a/500. The design curve is capable of conservatively predicting the ultimate resistance under axial compressive load, thus it could provide valuable references for designing MCFSTWs with four simply-supported edges.