Zhaoyang Fuxing Bridge (Chongqing) – Prestressed Steel Box Basket‑Handle Arch Bridge Case Study
Zhaoyang Fuxing Bridge is located at the Guanyinyan Gorge section of the Jialing River in Beibei District, Chongqing. It is a large‑span steel box basket‑handle arch bridge with a main span of 274 m. The arch ribs are assembled by cable‑supported cantilever method, and the deck system adopts a prestressed concrete structure.
Due to the narrow valley topography and high seismic intensity in the area, the bridge applies a “integrated cable‑tower and stay‑tower” hoisting system instead of the conventional jacking‑stay method, which greatly reduces the cost and difficulty of temporary works. Prestressing technology is widely used in the deck system, arch rib joints, and the ties of the basket‑handle arch to ensure the structural integrity and durability of the long‑span arch bridge.
| Construction Challenge | Description | Prestressed Solution |
|---|---|---|
| Rib segment positioning accuracy 274 m main span + narrow valley | The arch ribs are divided into many segments for cantilever assembly. The conventional jacking‑stay method would require large temporary structures and is highly affected by wind and temperature, making alignment control difficult. | Adopt integrated cable‑tower and stay‑tower hoisting system; pre‑tension the cable‑tower to improve overall stiffness; set up a monitoring network and use real‑time tension adjustment for the stay cables to ensure high‑precision closure of the arch ribs. |
| Structural system forces under “integrated tower” Complex force transfer in the temporary tower system | The integrated cable‑tower and stay‑tower shares the same foundation, and the load transfer path is complex. If the temporary tension in the stay cables is not properly matched, it may cause excessive deformation of the arch ribs or even local instability. | Establish a finite element model of the integrated tower to determine the rational match between cable tension and arch rib deformation; apply staged tensioning to gradually adjust the internal forces. |
| Tensioning of the basket‑handle arch tie system Limitation of narrow site for tensioning equipment | The basket‑handle arch requires a horizontal tie system at the arch springing to balance the thrust, but the narrow construction site on the valley slope restricts the placement of jacks. | Use a stranded wire tensioning system in combination with a steering pulley to change the tensioning direction, arrange the jacks at a remote location; control the force through oil pressure and elongation dual‑control to ensure the effective establishment of the prestressed ties. |
| High seismic intensity & durability Seismic zone + humid river environment | The bridge is located in a high‑seismic‑intensity area and is exposed to a humid river environment year‑round. The prestressing system is at risk of corrosion, and its seismic performance faces challenges. | Specify epoxy‑coated strands and corrosion‑inhibited grout; use unbonded prestressing tendons in the plastic hinge zones of the bridge towers to improve ductility and energy dissipation capacity. |
| High‑strength concrete for arch rib joints High local stress at joint sections | The steel arch rib joints are subjected to high local stress during the closure process, and the risk of concrete cracking is significant. | Apply local bonded prestressing at the joints; install steel fibers in the high‑stress areas; control the concrete grade and compaction to ensure joint integrity. |
| Grouting quality & void detection Curved cable ducts in the deck system | The deck system of the arch bridge contains longitudinally, transversely, and vertically curved prestressing ducts, where complete grouting is difficult to guarantee. | Use vacuum‑assisted grouting with high‑performance, corrosion‑inhibited grout; pre‑install grouting and venting pipes at all high points; perform ultrasonic or impact‑echo void detection. |
Achieved: integrated cable‑tower system, high‑precision arch closure, tie system effectively constructed, seismic & durability protection
✅ Achievements & Summary
Through the application of advanced prestressing technology:
· Successfully implemented the integrated cable‑tower and stay‑tower hoisting system in the narrow valley, avoiding a large number of temporary structures and achieving millimeter‑level closure accuracy of the arch ribs.
· Determined the rational match of cable tension and arch rib deformation through finite element analysis, effectively controlling structural forces.
· Used steering pulleys and remote tensioning to apply the tie system of the basket‑handle arch, overcoming the limitation of the narrow construction site.
· Enhanced the corrosion resistance and seismic performance of the prestressing system using epoxy‑coated strands, corrosion‑inhibited grout, and unbonded prestressing tendons.
· Applied local bonded prestressing at high‑stress joints and vacuum‑assisted grouting in curved ducts, achieving zero voids in the prestressing system.
Chongqing Zhaoyang Fuxing Bridge demonstrates how advanced prestressing technology can enable the safe construction of large‑span steel box arch bridges under complex mountainous conditions, providing a long‑lasting, durable solution for regional infrastructure.
