Influence of Welding Residual Stress on Ultra-Low Cycle Fatigue Properties of Beam-Column Joints in Steel Frame.

Welding technology is widely used in the steel structure forming process. After welding, there is uneven residual deformation in the structure, resulting in welding residual stress. In this paper, the damage process of beam-column joints in steel frames under ultra-low cycle fatigue loading was simulated by ABAQUS software. The crack initiation position of the joints was obtained. On this basis, the influence of welding residual stress on the development of tensile and bending fatigue damage of beam-column joints in steel frames was analyzed. In parallel, the effect of welding residual stress on the fatigue damage process of joints with different loading modes and different beam flange widths was discussed. The results show that during ultra-low cycle tensile and bending fatigue, cracks are both initiated at the welding holes of the beam flange, but the cycle number required for crack initiation is different, and the cycle number to failure of bending fatigue is greater. The residual stress can accelerate crack initiation and advance approximately two cycles. For bending fatigue damage, the crack first originates from the flange in tension first, and the average cycle number to failure of the flange is 12.85% more than that of the other flange. With the flange width decreasing from 150 to 130 mm, the cycle number to failure affected by residual stress rises from 5.30 to 13.56%. With the increase in cycle number, the damage development of a single cycle is more affected by the residual stress, the increasing trend of the fracture index remains unchanged, and the growth rate becomes faster. [ABSTRACT FROM AUTHOR]