Numerical investigation on strength design and curling effect of mechanically fastened joints in cold-formed austenitic stainless steel

A variety of parametric studies utilizing the finite element analysis (FEA) have been performed by Kim et al in order to predict the mechanical behavior (ultimate strength) of single shear bolted joints in cold-formed (thin-walled) stainless steel sheet. Strength equations considering the strength reduction by curling effect in bolted joint with long end distance and edge distance have been suggested. The applicability of numerical fracture analysis has been already verified through the comparisons of ultimate strength and curling occurrence between the test results conducted by Kuwamura et al. and FEA results. The precedent researches have been conducted with respect to the mechanical behaviors of single shear bolted joints fabricated with four bolts (2 columns × 2 rows bolt arrangement) and two bolts (1 column × 2 rows bolt arrangement) for extended variables such as plate thickness, end distance parallel to the direction of load and edge distance perpendicular to the direction of load. Subsequently, this study has been focused on the ultimate behaviors and the influence of curling on ultimate strength in bolted joints fabricated with one bolt. FE models are assumed with varying end distance, edge distance and plate thickness. It is found that the design manual of Stainless Steel Building Association of Japan (SSBA) is more reasonable for estimating the ultimate strengths of bolted joints with no curling compared with ultimate strengths predicted by American Society of Civil Engineers (ASCE) standard or American Iron and Steel Institute (AISI) standard (North American specification). Whereas, for fastened joints with severe local buckling or out of plane deformation(hereafter, curling) like previous results about other bolt arrangements, even SSBA manual tended to overestimate the ultimate strength of joint. Also, it has been known that the conditions of curling occurrence differ from the above stated variables. Therefore, revised strength equations considering the strength reduction by curling for one bolted joint were suggested in this paper.

► We performed finite element analysis and parametric studies for fastened joints.
► Ultimate strengths by FEA were compared with those by current design specification.
► Conditions of curling according to plate thickness, end distance and edge distance were proposed.
► Modified equation considering strength reduction caused by curling was suggested.