Flexural performance of weld-strengthened steel beam-square column joints subjected to axial column loading

Abstract

This study proposes a novel strengthened joint with external rib plates for the H-shaped-beam square-column (HBSC) steel frame. The thermal effect of welding under load on the flexural performance of this joint was examined experimentally, numerically, and theoretically, both during and after the welding process. The following significant findings have been reported. The rib plates do not convey the axial pressure when welded to the column wall; consequently, the maximum thermal strain occurs on the column wall below the weld seams, reducing the column's stiffness and negatively contributing to the joint's flexural resistance. While the rib plates transmit force when they are welded to the angle steel, at this time, the rib plates experience the most significant thermal strain. The thermal effects of welding have been evaluated using a finite element model (FEM). Considering thermal effects, the FEM suggests a reduction factor of 0.90 for the load-bearing capacity. The yield strength of the strengthened joint is roughly double that of the unstrengthened joint, indicating that the reinforcement is effective. The initial stress ratio of the column must be kept below 0.7 to limit the rate at which the yield strength of the strengthened joint decreases as the compressive load increases. The stress distribution ratio between the vertical rib and the column wall has been determined using a simplified mechanical model. Based on the yield line principle, a formula for calculating the yield capacity of the strengthened joint has been derived.