English：

The steel arch of the Dongyixian Bridge spanning the Jiangxi River has a waist-round cross-section and a spatially twisted shape. The manufacturing quality of the bent and twisted semi-circularsteel pipes on both sides directly affects the overall effect of the components. Therefore, themanufacturing method and control measures for the super-large cross-section gradually changing bent andtwisted waist-round steel arches are adopted. This not only meets the bending arc requirements within thecross-section but also satisfies the longitudinal twisted arc effect within the segments. By segmenting thebent and twisted steel arch, the large-diameter thick-walled bent and twisted steel pipes are processedinto shape and precisely cut. The intelligent cutting technology and full penetration welding technologyare used to cut and weld the intersection lines of the large-sized steel pipes. After eliminating the residualstress of the welds at the intersection lines, the on-site installation is carried out to complete themanufacturing of the super-large cross-section gradually changing bent and twisted waist-round steel arch.Its manufacturing accuracy is high and the bridge effect is good, the fatigue resistance of the welds of thisbridge is good, ensuring the service life of the bridge structure.