Abstract:The main bridge of Fujiang Bridge on Qingshi Road in Mianyang City is a (100 m+180 m+100 m) three-span continuous arch-beam composite system bridge. The standard deck width is 42.0 m, and the widening section reaches 52.0 m. The rise height of the side span arch ribs is 11.5 m, and the rise-span ratio is 1/8.7. The rise height of the middle span arch ribs is 24.5 m, and the rise-span ratio is 1/7.3. The arch ribs feature an inverted trapezoidal cross-section, and the mesh cross braces are used between the arch ribs. The steel girders are in a double-sided box variable height section, and a girder height is 2~6 m. The rigid mesh suspension rods are used between the steel girders and the arch ribs. The anchoring of the suspension rods to the arch ribs and the steel box girders are all used of integral welded joints. Rigid mesh suspension rods effectively reduce the bending moment of the arch ribs, enhance the structural rigidity, and improve the force-bearing performance of the bridge structure. In terms of form, it is consistent with the mesh horizontal bracing, jointly creating the design concept of “Tunnel of Time and Space”. In terms of durability, the need for the replacement of flexible slings can be eliminated and a service life is longer. An overall construction scheme of beams first and then arches is used for the superstructure of the main bridge, in which the variable-height steel box girders are constructed using a leveling formwork followed by a bidirectional incremental launching construction process, which greatly accelerates the construction progress.
