Numerical investigation of the plastic behaviour of short welded aluminium double-T beams

The present work is a numerical approach to the mechanical behaviour of short aluminium beams, both extruded and welded at the web–flange junction. The studied beams were taken to be short so as to ensure that their design is dominated by shear. In order to investigate the effects of the weld and the consequent existence of a heat-affected zone (HAZ), both welded and extruded beams of identical geometric characteristics were studied. Three alloys, 6063-T6, 6005A-T6 and 7020-T6, were chosen because of their varying strength characteristics, as well as the different severity of mechanical degradation that each one undergoes in the HAZ. The numerical investigation is performed in the framework of small displacements, and the possibility of lateral buckling is excluded. All the studied cases qualify as Class-I cross sections for normal actions. The Ramberg–Osgood stress–strain relation is used to describe the hardening of the material. The results obtained by means of finite element models are compared to those of classical beam theory and to the resistance checks of Eurocode 9.