Experimental and Numerical Evaluation of Residual Displacement and Ductility in Ratcheting and Shakedown of an Aluminium Beam

Safety assessment of structures can be obtained by means of limit design in order to overcome uncertainties concerning actual response due to inelastic constitutive behaviour and more generally to non-linear structural response and loads’ random variability. The limit analysis is used for evaluating the safety of the structures directly starting from load level without any knowledge of the load history. In the paper, the lower bound calculation is proposed based on permanent strain parametric description of the residual stress. The strategy allows considering the permanent strain as the effective parameters of the procedure and can be used to control the ductility requirements until complete load program develops. In this way one can control if the structure can develop entirely its possibility of plastic adaptation up to required load level. The procedure is compared to experimental results obtained on aluminium beams in shake down.