Single shear screwed connection tests of thin sheet steel at elevated temperatures

摘要

The design rules on screwed connections of thin sheet steel in the current International specificationsrnfor cold-formed steel structures are only applicable for ambient temperature. Up-to-date, investigationrnof screwed connections at elevated temperatures is quite limited. In this study, a total of 24 single shear screwedrnconnection specimens fabricated from G550 0.42 mm, G500 1.20mm and G450 1.90mm thin sheet steels werernconducted by transient state test method. The tests were performed at three different load levels of 25%, 50% andrn75% of the failure load at ambient temperature. The critical temperature and the corresponding displacement ofrnscrewed connections were obtained from the transient state test curves. The connection strength deteriorationrnobtained from the transient state tests was compared with that obtained from steady state tests. The critical temperaturesrndetermined by the transient state test results are slightly higher compared with those deduced from thernsteady state test results at similar load levels, and even higher than those from the coupon test results. Differentrnfailure modes, such as bearing, tear out, material failure and several combined failure modes were observed inrnthe transient tests. It is found that the failure mode of the screwed connections may change as the load levelrnincreases.