Ultimate strength of lean duplex stainless steel single-shear bolted connections with four bolts

Abstract

The recently developed lean duplex stainless steel (STS329FLD, KS) offers higher strength, greater corrosion resistance and lower cost compared with austenitic stainless steel (STS304 and STS316, KS) due to reduced nickel content. However, stainless steels are not included under structural materials in Korean Design Standards (KDS), and the corresponding design specifications are not regulated. In this paper, the structural behaviour of lean duplex stainless steel (STS329FLD) four-bolted connections were investigated through a parametric finite element analysis. The effectiveness of the analysis model was verified through a comparison of the test results. The main variables are end distance parallel to the direction of applied force and edge distance perpendicular to the direction of applied force. Curling (Out-of-plane deformation in the plate thickness) occurred in both test and analysis. It is found that curling reduced ultimate strength by up to 29%. Conditions of end distance and edge distance for lean duplex stainless steel bolted connection with a strength reduction effect caused by curling were investigated. Strengths according to current design specifications and equations proposed in previous studies were compared with analysis strengths. A modified equation was suggested that considers both actual fracture mode at ultimate state and the effect on strength caused by curling. © 2020 Elsevier Ltd