NONLINEAR RESPONSE OF THE LOCALLY BUCKLED COLD-FORMED BOX BEAM-COLUMN

The nonlinear response of the locally buckled box beam-column is reported in this paper. The locally buckled beam-column is treated as a model where the beam-column is divided into a series of the locally buckled cells that are connected at their ends. A large-deflection elastic-plastic finite strip analysis is implemented to calculate the elastic-plastic M-P-Φ curves of the cells. Then a finite integration approach is employed to evaluate the ultimate load of the beam-column.A test program on the cold-formed box columns loaded eccentrically was performed. The comparison of experimental and numerical results shows a good agreement. A design formula is proposed to estimate the ultimate strength of the cold-formed box columns subjected to a concentric loads.