Effects of End Distance and Temperature on Thin-Sheet Steel Double Shear-Bolted Connections

An experimental investigation was conducted with thin-sheet steel (TSS) double shear-bolted connections at elevated temperatures. The connection specimens were fabricated by TSS 0.42-mm G550 and 1.90-mm G450. The specimens were designed with variation in end distance. The tests were conducted at five different nominal temperature levels up to 900°C using the steady-state test method. The variation of the end distance and temperature on the behavior of the connection specimens was investigated. The increment of the connection ultimate load was found as the end distance increased up to five times the diameter of the bolt. It was also found that deteriorations of connection strengths occurred in a similar manner to the corresponding material properties at elevated temperatures. At each nominal temperature level, as the end distance increased, the failure modes of specimens changed from tearout to bearing. The experimental results were compared with predictions by using international design codes for cold-formed steel structures, including NAS 2016, EC3-1.3, and AS/NZS 2018. In calculating the nominal strengths of the connections, the reduced material properties of TSS obtained at elevated temperatures were used. Overall, the predictions from NAS, EC3-1.3, and AS/NZS were found to be conservative, with AS/NZS providing the least conservative and least scattered predictions. In general, NAS and AS/NZS could accurately predict the failure modes for TSS connection specimens that failed in tearout and bearing failure at different temperature levels.