Effects of end distance on thin sheet steel single shear bolted connections at elevated temperatures

Thin sheet steel (TSS) single shear bolted connections at elevated temperatures were investigated experimentally in this study. The TSS 0.42 mm G550 and 1.90 mm G450 were used to fabricate the connection specimens. The connection specimens were designed with the variation of end distance. The specimens were tested at 5 different nominal temperature levels up to 900 degrees C using the steady state test method. The effects of end distance and temperature on the behaviour of bolted connections were investigated. It was found that the ultimate loads increased with the increment of the end distance up to three times the bolt diameter. Generally, the deteriorations of the connection strengths are in a similar manner to the corresponding material properties at elevated temperatures. The experimental results were compared with the predictions by using the Australian/New Zealand Standard (AS/NZS), European Code (EC3-1.3) and North American Specification (NAS) for cold-formed steel structures. In calculating the nominal strengths of the connections, the reduced material properties of TSS obtained at elevated temperatures were used. Overall, it is shown that the predictions from the AS/NZS, NAS and EC3-1.3 are conservative, with the AS/NZS providing the least conservative and least scattered predictions. However, the reliability analysis showed that the design provisions of the three design specifications are not reliable for the TSS single shear bolted connections in this study, with considerable scope for the development of improved design formulae. Generally, the AS/NZS and NAS could provide accurate predictions of failure modes for TSS connection specimens failed in tearout failure and bearing failure at different temperature levels.