Assessment of hysteretic cyclic behaviour of plastic hinge in cold-formed steel beams

In this paper on the base of recently performed experimental results the behaviour of cold-formed steel beams subjected to monotonic and cyclic loads is analysed with particular reference to the plastic hinge experienced by the member after the attainment of local buckling. The experimental results, which showed not negligible deformation and energy dissipation capacities up to the failure of the tested beams, have been elaborated in terms of moment-rotation relationship of the plastic hinge. It represents its hysteretic cyclic behaviour, which is affected by significant stiffness and strength cyclic degradation. Finally, a numerical model of the hysteretic cyclic curve has been assessed, based on simple degradation rules, which take into account both the reduction of resistance due to the degrading branch and the plastic excursion experienced by the hinge.