Inelastic flexural strength of aluminium alloy structures

In this paper, the results of an extensive numerical study devoted to the evaluation of the inelastic flexural behaviour of aluminium alloy structures are provided. The main aim of the research is to determine the required ductility for applying simplified methods of plastic analysis (i.e. plastic hinge method) to structural systems made of materials characterised by a continuous hardening and with limited deformation capacity. Therefore, the cross-section rotational capacity necessary to attain predefined levels of load bearing capacity is evaluated for different structural schemes and then compared to the available rotational capacity corresponding to fixed thresholds of ultimate cross-section curvature. The influence of both geometrical (cross-section shape factor and structural scheme) and mechanical (material hardening and ultimate deformation capacity) parameters is taken into account. The parametric analysis is performed by using a numerical model implemented in the implicit non-linear FE code ABAQUS/Standard and calibrated on available experimental tests. On the basis of the above analysis, the limit values for the rotational capacity of a cross-section in bending necessary to guarantee adequate inelastic redistribution of internal forces for continuous beams and framed structures are given. Finally, new indications for the application of the modified plastic hinge method included in Eurocode 9 are provided.