Effects of material property and thickness on block shear strength in lean duplex stainless steel welded connections

Abstract

Recently, studies have been carried out to apply lean duplex stainless steels, with less than 1.5% nickel, which provides higher material strength and lower cost compared with austenitic stainless steel for building structures. This study compared with existing experimental and finite element analysis results on the structural behaviours of cold-formed lean duplex stainless steel welded connections with different tensile strength (tensile strength-to-yield stress ratio) and plate thickness despite identical steel grade. The main variables are plate thickness and weld lengths. The material tensile strength of a 3.0 mm thick plate was 22% lower than that of a 1.5 mm thick plate. All specimens showed block shear facture in the base metal. Block shear strengths predicted by current design codes and the proposed equations from previous studies were compared with test strengths. KDS 41 31 00-19/AISC2016 and EC3 design specifications underestimated block shear capacity by on average 24%, 43%, respectively for 1.5 mm and 3.0 mm thick specimens, and equations suggested in previous studies of stainless steel welded connections did not sufficiently account for the influence of stress triaxiality by material property and plate thickness difference on the block shear strength of lean duplex stainless steel specimens. Therefore, thickness-dependent modified strength equations were recommended based on experimental and numerical studies of lean duplex stainless steel welded connections and comparison of carbon steel and other stainless steel connections.