Abstract:The Xiaohe River Bridge on Dayun Road is the world's first large-span spiral-shaped spatially asymmetric landscape arch bridge. This bridge breaks through the traditional arch bridge design, refining the curve elements and transforming them into a closed spiral-shaped spatial ribbon arch bridge comprising two spans of asymmetric ribbon inclined secondary arches and a single span of a diagonal main arch. This design creates a sense of passage and dynamic movement, with nested arches and landscapes. The bridge has a total span arrangement of 65+110+110+65 = 350 m. The main beam and transverse beams are connected with the main and secondary arches, forming an arch?beam joint system. This structure transforms the mechanical properties of the irregular spiral-shaped spatially asymmetric ribbon landscape arch bridge into an arch–beam composite system. This system is characterized by structural self-balancing and no horizontal thrusts. The main and secondary arch ribs are designed with parabolic arch axes and box-type cross sections. The main arch span is 229 m, which is the largest diagonal spanning arch bridge in China. The transition segments (the arch feet) connecting the main and secondary arches with the transverse beams are twisted surface components made from Q370qD steel with a plate thickness of 40 mm. The main beam adopts a semi-closed double-sided steel box section. The bridge has undergone comprehensive analyses, including spatial static, fatigue, stability, and seismic performance evaluations, as well as refined analysis of the arch feet. The results indicate that the structure is safe, reliable, and meets the relevant design code requirements.