Experimental study and numerical simulation analysis of the Bolted-Welded hybrid connection joint of steel frame under fire

Abstract

As an important part of the steel frame structure, the bolted-welded hybrid connection joint has a significant impact on the overall behavior of the structure and the prevention of progressive collapse, especially under fire exposure. Therefore, a fire test of three specimens with bolted-welded hybrid connection joints was carried out in this paper. The effects of beam-end load ratio and concrete slab thickness on the fire resistance of bolted-welded hybrid connection joints were investigated. The connection performance and failure mechanism of this connection joint under fire exposure were revealed. The furnace temperature - time curves, the surface temperature - time curves of the components, the vertical displacement - time curves of the beam end and the column top, the joint angle - time curves, the joint angle - temperature curves, the fire resistance time, and the critical temperature were obtained. The test results show that the load ratio has a great influence on the fire resistance of the bolted-welded hybrid connection joint. With the load ratio increasing, the time for the bolted-welded hybrid connection joint to reach the fire resistance limitation is significantly shortened, and the maximum anti-arch value at the beam end is significantly reduced. The increase of concrete slab thickness improves the fire resistance of the bolted-welded hybrid connection joint, but the improvement is small. A finite element model of three bolted-welded hybrid connection joints of steel frame specimens was established using ABAQUS software. A parametric analysis of load ratio and concrete slab thickness was carried out, and the mechanical behavior and failure modes of each specimen under fire exposure were numerically simulated.