Behaviors of high strength steel connections in fire

Experimental and numerical studies were presented in this paper to investigate the fire behavior of high strength steel (Q690 and Q960) shear and T-stub connections. The load–displacement curves, failure modes, and load capacities at elevated temperatures were obtained from the experiment. Finite element models were established by ABAQUS software and validated by the test results. The test capacities of shear connections were compared with those predicted by EC3, AISC 360-16, and GB50017, while the test capacities of T-stubs were compared with that predicted by EC3. Results show that the failure temperature from brittle failure to ductile failure is approximately 500 ℃ for shear connections. The load capacity predicted by AISC 360-16 is accurate, while EC3 and GB50017-2017 are conservative for shear connections. The failure mode of T-stubs changed from the flange rupture to the bolt failure with yielding of the flange when the temperature was higher than 600 ℃. EC3 provides conservative results, while the modified equations accurately predict the first yield resistance for the T-stubs.