Effectiveness of Analysis Procedures on Buckling Loads of Steel Portal Frames

In this paper, different finite element models has been adopted to investigate the effectiveness of analysis procedures on the critical buckling loads of steel portal frame. In the linear approach where most analysis softwares adopts, the members imperfection are neglected, this can be leads to overestimate frame buckling strength. Therefore this paper aim to compare the critical loads obtained by the linear eigenvalue buckling analysis with corresponding value determined by the non-linear Riks method where the members imperfection are included. Different beam, column and loading nature has been considered in the finite element simulation. The results indicated that, the critical buckling loads obtained by the linear approach could give an overestimate buckling strength by 18 % for the steel portal frame loaded with line load on its beam. A critical load reduction factor has been developed, for frames that are imperfection sensitive, with correlation coefficient of 0.907.