Thermal buckling of rotationally restrained steel columns

The in-plane elastic buckling of a steel column under thermal loading is investigated. Two elastic rotational springs at the column ends are used to model the restraints which are provided by adjacent structural members or an elastic foundation. The temperature is assumed to be linearly distributed across the section. Based on a nonlinear strain-displacement relationship, both the equilibrium and buckling equations are obtained by using the energy method. Then the buckling of columns in three different thermal loading cases is studied. The results show that the proposed analytical solution can be used to predict the critical temperature for elastic buckling. The thermal gradient plays a positive role in improving the stability of columns. Furthermore, the effect of thermal gradients decreases while increasing the rotational restraint stiffness and decreasing the slenderness ratios of columns. It can also be found that rotational restraints can significantly affect the column elastic buckling loads. Increasing the rotational stiffness of thermal restraints will increase the critical temperature.