BUCKLING OF AN AXIALLY RESTRAINED STEEL COLUMN UNDER FIRE LOADING

Analytical procedure, based on the linearized stability analysis, is presented for the determination of the buckling load and the buckling temperature of a straight, geometrically perfect, axially loaded steel column subjected to an increasing temperature simulating fire conditions. The nonlinear kinematical equations and the nonlinearity of material are considered. The stress strain relation for steel at the elevated temperature and the rules for reduction of material parameters due to increased temperature are taken from European standard EC 3. Theoretical findings are applied in the parametric analysis of a series of Euler's columns subjected to two parametric fires. It is found how the slenderness of the column, the material nonlinearity, the temperature dependence of material parameters, and the stiffness of restraints at supports effect the critical temperature. While these parameters have major influence on the critical temperature, they have no effect on the shape of the buckling mode.