Experimental investigation of plastic collapse of aluminium extrusions in biaxial bending

In this work results of an experimental study on the bending collapse of thin-walled beams subjected to biaxial bending (i.e. moment with components with respect to the section principal axes) are reported. The objective of the present work is to get a fundamental understanding of the phenomenon with particular enphasis to the test loading conditions and to the identification of the most suitable parameters for the description of such a large rotation collapse. The test equipment, specifically designed and build to execute biaxial bending tests, is briefly described. A series of tests was made on thin-walled aluminium structural components, with square and rectangular section. The study is focused on the description of the collapse and the post-collapse behaviour under in-plane and biaxial loading conditions. The adopted loading procedures, of the constrained bending plane type allows to study the evolution of the resisting moment (and of its components) developped during the collapsing process.The behaviour was analyzed under two points of view: a global one, with the determination of the structural response as per generalized loads and displacements, and a local one, through the study of the kinematic of the plastic hinge mechanism.