Post-fire tensile behavior of hole-anchored bolted T-stub connection

Abstract

Hole-anchored Bolt (HB) is a kind of blind bolt whose anchorage is provided by the threads tapped in bolt hole instead of the nut, for which it could be installed from out-side of the steel component with closed-section. The HB provides an alternative way to connect the beam-column connection with closed-section component. A test was designed and conducted to study the behavior and to verify the applicability of HB bolted T-stub connection under tensile force at post-fire condition in this paper. The full-time test method was used in the test to simulate the whole progress of a fire, including the loading stage at ambient temperature, firing stage under constant load and the loading stage after cooling. Influence of the HB diameter, hole thickness, load ratio as well as the exposed temperature to the post-fire tensile performance of HB bolted T-stub were analyzed. Increase of the hole thickness and the HB diameter could increase the residual bearing capacity of the T-stub connection effectively. Failure mode of the T-stub connection was also decided by the HB diameter and the hole thickness. Load ratio and suffered temperature influenced the failure stage of the connection but had little influence on the failure mode and the residual tensile resistance. The T-stub with same configuration using Traditional High-strength Bolt (THB) were also tested. Comparison of the results showed the post-fire tensile resistance of HB bolted T-stub was little smaller than the THB ones with same configuration. The HB connected T-stub could regain at least 80.9% of their ultimate load and 87.1% of their yielding load after cooling from fire. The residual ultimate resistance was still higher than the design requirement, which showed the post-fire performance of HB bolted T-stub connection could still satisfy the design requirement.