Postbuckling shear capacity of high-strength steel plate girders

Abstract

Postbuckling capacity of plate girders still occurs after the occurrence of local buckling in the web panel. The postbuckling capacity of mild steel plate girders gradually develops because mild steel exhibits a clear yielding point and a yielding plateau. However, there are no clear yielding points nor distinct yielding plateaus for the high-strength steel (HSS) Q550 and Q690. Even though the postbuckling shear resistance is considered for the mild steel plate girder design in many international design codes, the design formula suggested for mild steel plate girders might not be suitable for HSS plate girders. The objective of this research is to quantify the shear resistance for HSS plate girders. The buckling strength and postbuckling capacity of HSS plate girders are investigated in this study by performing the nonlinear finite element analyses (FEA) that includes the tested material properties. The tested stress–strain curves of HSS Q550 and Q690 are idealized by bilinear and multilinear models. This shows that the strain hardening do have an effect on the postbuckling capacities of HSS plate girders. Therefore, a more accurate multilinear material model is selected for further FEA on the shear resistance of plate girders. The differences between the FEA and EC3 formulae outcomes are notably identified. Based on the numerical studies, a new buckling coefficient formula and a new ultimate shear resistance formula for HSS plate girders are proposed in the study.