Experimental Study on Shear Performance of High⁃Strength Bolt Efficient Connections at Elevated Temperatures

To investigate the shear-bearing capacity of high-strength bolt efficient connections with high slip-resistant coefficients under elevated temperatures， tensile tests were first conducted on Q355 and Q960 base material specimens （matching the connection components） and Grade 8.8 bolt material specimens under both ambient and high-temperature conditions. This established the temperature-dependent relationships for elastic modulus， yield strength， and tensile strength of the materials. Subsequently， high-temperature shear performance tests were performed on eight high-strength bolt efficient connections to examine the effects of different temperatures and hole configurations on failure modes， slip loads， and ultimate loads. The results demonstrate that： the failure mode of high-strength bolt efficient connections transitions from net-section failure to bolt shear failure within the 300-400°C temperature range； both slip load and ultimate load decrease with increasing temperature， showing 75% and 51% reductions respectively at 500°C compared to ambient conditions for standard hole specimens； different hole configurations exhibit limited influence on the ultimate shear capacity of connections at 500 °C.