Effect of rotational stiffness at column base of portal frame at elevated temperature

In this paper, numerical models are developed to predict the true behavior of portal frames at elevated temperature. These models are fully capable of capturing the snap-through-buckling and the post-buckling behaviour. It is found that after buckling, the rafter takes the cantenary shape whose compressive stress is transformed into tensile stress and pulls the top of the column inward. A parametric study on the rotational stiffness of the column base is conducted. It was found that at a lower rotational stiffness, the structure experiences snap-through at lower temperature; and increase of rotational stiffness provides stabilization of rafter and which yields a higher buckling temperature. Increasing the partial strength of column base increases the snap-through buckling temperature.