This paper is focused on the structural behavior of the single shear bolted connections with thin-walled ferritic stainless steel. The purpose of this study is to investigate the ultimate behaviors, such as ultimate strength and fracture mode of the single shear bolted connections of thin-walled ferritic stainless steel (low cost steel) rather than austenitic stainless steel (high cost steel). Bolt arrangement and end distance parallel to the direction of applied load are considered as main variables of the test specimens for bolted connections. Specimens have a constant dimension of edge distance perpendicular to the loading direction, bolt diameter, pitch, and gauge. A monotonic tensile test for specimens has been carried out and some bolted connections with long end distance showed curling (out of plane deformation) occurrence which led to strength reduction. The ultimate behaviors such as fracture mode, ultimate strength are compared with those predicted by current design codes. Further, conditions of curling occurrence and the strength reduction due to curling are investigated and modified strength equations are suggested considering the curling effect.

This article presents the experimental and numerical results of cold-formed ferritic stainless steel (STS430) bolted connection with two bolts. Single-shear bolted connections with varying end distance were planned and tested. Block shear fracture and curling (out-of-plane deformation) were observed in specimens. Finite element analysis was performed to investigate the conditions for curling occurrence and the curling effect on the ultimate strength of ferritic stainless steel bolted connections with extended end distances and edge distances varying from 24 to 60 mm. Curling occurred for bolted connections with end distances exceeding 39 mm and edge distances exceeding 30 mm. Ultimate strength of curled specimens was reduced up to 33% compared to the ultimate strength of uncurled connection. Since current design equations do not consider the curling effect and the difference in material properties, they did not provide accurate ultimate strength predictions of specimens with typical block shear fracture and curling occurrence. Therefore, a modified block shear equation was suggested for ferritic stainless steel bolted connection with typical block shear fracture mode, considering the actual fracture path and shear stress factor. A revised equation was also proposed for specimens with strength reduction by curling influence, considering the concepts of bearing action against connected plate by bolt (bearing factor, C = 1.6) and net-section tensile fracture between two bolts perpendicular to the direction of the applied force. Moreover, additional experiments for six specimens were performed and the reliability of the two suggested equations in this study was verified.