Inelastic behavior of standard and retrofitted rectangular hollow sectioned struts. I: Analytical model

This paper is a presentation of a physical model for the elastic-partly pla stic behavior of rectangular hollow section pinned struts subjected to stat ic cyclic axial loading and the evaluation of the compressive strength of r etrofitted damaged struts. Retrofitting is achieved by welding stiffening p lates along the webs of damaged struts. The shape of the elastic and perman ent deformations of the strut axis satisfy the conditions at the ends and m idspan. Continuous functions of the geometric variables of stress distribut ions in the yielded zone are evaluated by interpolation between three point s along each partly plastic zone. Permanent deformations of the partly plas tic region are computed and used to update the shape of the unloaded strut. The necessity of considering geometric nonlinearity is discussed. The sens itivity of the results to the location of interpolation points, the shape o f the permanent deformation and material hysteretic properties is investiga ted.