Experimental and numerical studies on the behavior of high strength steel shear connections at elevated temperatures

Abstract

This paper presents experimental and numerical studies to investigate the fire behavior of high strength steel (Q690 and Q960) shear connections. The load-displacement curves, failure modes, and load capacities, including the slip load and ultimate load of the specimens at elevated temperatures were obtained from experiments. A finite element model was established by ABAQUS software and validated by the test results to investigate the effect of the friction coefficient and the assembly form of the bolt on the shear behavior. The numerical results of load capacity were compared with that predicted by EC3, AISC 360–16, and GB50017. Parametric studies were conducted to investigate the effect of the slip load on the ultimate load at ambient temperature, and design methods were proposed considering the friction coefficient and preload values. The research shows that the slip load decreases more rapidly than the ultimate load at elevated temperatures. The critical temperature from brittle failure to ductile failure is approximately 500 °C. The load capacity predicted by AISC 360–16 is accurate, while EC3 and GB50017-2017 predict conservative load capacity. The effect of the bolt load and friction coefficient cannot be ignored for high strength steel shear connections.