Non-linear buckling analysis of steel frames with local and global imperfections
Keywords:Steel frames, buckling, imperfection’s pattern, structural optimization.
The problem related to nonlinear analysis of steel frames is analyzed by taking into account local and global imperfections. A new method for estimation of optimal (in the worst case scenario causes smallest buckling load) pattern for geometrical and material imperfections is developed. The method is based on the optimization of structural topology. The topology is optimized in a way where maximal compliance (minimal stiffness) and strain energy is reached. According to the gradient of compliance function the pattern of geometrical and material imperfections is iteratively obtained. Global geometrical imperfections are applied by using buckling modes (Eigenmodes) with a pre calculated weight coefficient according to the compliance function for each buckling mode. The proposed methods showed to be robust and practically applicable for designing complex steel structures.