Influence of Welding Residual Stress on the Structural Behaviour of Large-Span Steel Tube Arch Rib

The steel tube arch rib in a large-span concrete-filled steel tube arch bridge has a large span and diameter, which also leads to a larger weld seam scale. Large-scale welding seams will inevitably cause more obvious welding residual stress (WRS). For the purpose of studying the influence of WRS from large-scale welding seam on the mechanical properties of steel tube arch rib during arch rib splicing, test research and numerical simulation analysis on the WRS in arch rib splicing based on the Guangxi Pingnan Third Bridge, which is the world’s largest span concrete-filled steel tube arch bridge, were conducted in this paper, and the distribution pattern of WRS at the arch rib splicing joint was obtained. Subsequently, the WRS was introduced into the mechanical performance analysis of joints and structures to analyze its effects. The findings reveal that the distribution of WRS in the arch rib is greatly influenced by the rib plate, and the axial WRS in the heat-affected zone are primarily tensile, while the circumferential WRS are distributed in an alternating pattern of tensile and compressive stresses along the circumferential direction of the main tube. Under the influence of WRS, the ultimate bearing capacity of the joint is reduced by 29.4%, the initial axial stiffness is reduced by 4.32%, and the vertical deformation of the arch rib structure is increased by 4.7%.