An investigation of the collapse of thin-walled rectangular beams in biaxial bending

Abstract Two different thin-walled closed sections, one square and one rectangular were tested in biaxial bending using displacement controlled cantilever bending tests. Two different constraint conditions were used, the first kept the deflection axis fixed and left the direction of the load axis free. The second kept the load axis direction fixed and allowed the beam to deflect freely. Each configuration was repeated at 15° axis intervals and was performed twice to assure repeatability. This gave a total of 42 cantilever bending tests. The results are used to compare the beam behaviour in the transition and collapse stages between the two constraint conditions. The behaviour is also contrasted with thick-walled theory predictions, since this is the only currently available reference.