Buckling and post-buckling analysis of restrained non-uniform columns in fire

Abstract

This paper investigates the buckling and post-buckling behavior of restrained non-uniform columns in fire where the temperature surrounding the column varies along the longitudinal direction. The material properties of the column are considered to be temperature-dependent (TD). First, according to the convective–radiative condition on the surfaces of the column, a dimensionally reduced nonlinear heat transfer equation is proposed and is solved by the differential quadrature (DQ) method. Then, considering the geometric imperfection, the nonlinear governing equation is derived based on the von-Kármán theory when the column is subjected to an axial compression load at the column end. An improved DQ method is applied to the buckling and post-buckling analysis of the non-uniform column under the fire. Considering the yield strength of material at elevated temperature, the ultimate load of the column is obtained. A tapered H-section steel column surrounded by localized fire is taken as an example. The present results are verified by comparing with those in the literature and those obtained from the finite element (FE) method. The parameter analysis reveals the temperature distribution, the buckling and post-buckling behavior of the tapered column in the localized fire.