Ultimate load analysis of thin-walled box beams considering shear lag effect

In this paper, the ultimate load of thin-walled box beams undergoing limited plastic strain is investigated with consideration of shear lag effect on the basis of the stress–strain relationship of elastic, linearly hardening materials. In the procedure, calculation formulae for strength increase coefficient, flange effective width ratio, critical values of plastic strain and shear lag coefficient are obtained for thin-walled box beams with elastic, linearly hardening materials. In addition, the relationships among the abovementioned parameters and conditions of boundary, load and aspect ratio L/2b (span length/beam width) of the box beams are established in this paper. For illustration, the numerical results of box beams under certain boundary and load conditions are presented and some conclusions are drawn which may offer references for the application of this procedure in structural design.