ULTIMATE STRENGTH FORMULAE FOR ALUMINUM PLATES AND STIFFENED PANELS UNDER AXIAL COMPRESSIVE LOADS

摘要

It is commonly accepted that the collapse characteristics of aluminum structures are similar to those of steel structures until and after the ultimate strength is reached, regardless of the differences between them in terms of material properties. However, it is also recognized that the ultimate strength design formulae available for steel panels cannot be directly applied to aluminum panels even though the corresponding material properties are properly accounted for. This is partly due to the fact that the stress versus strain relationship of aluminum alloys is different from that of structural steel. That is, the elastic-plastic regime of material after the proportional limit and the strain-hardening play a significant role in the collapse behavior of aluminum structures, in contrast to steel structures where the elastic-perfectly plastic material model is well adopted. Also, the softening in the heat-affected zone (HAZ) significantly affects the ultimate strength behavior of aluminum structures, whereas it can normally be neglected in steel structures. In this paper, the ultimate strength characteristics of aluminum plates and stiffened panels under axial compressive loads are investigated through ANSYS elastic-plastic large deflection finite element analyses with varying geometric panel properties. An 'average' level of welding-induced softening and initial imperfections is assumed for the analyses. Useful ultimate compressive strength formulae for aluminum plates and stiffened panels are empirically derived through a regression analysis of the computed results.