Cable-stayed bridge cable girder anchorage common structure

Common Anchorage Structures for Cable-Stayed Bridges. In recent years, a suspension bridge system has emerged in which the main cables of the main span are distributed and staggered on the bridge towers, and the towers are balanced by the stay cables in the side spans. Various modern cable-stayed bridges spanning major rivers, bays, and other natural barriers are constantly appearing.

In the field of cable-stayed bridge technology, the anchorage connection of the stay cables to the steel main girder has become a key technical issue in design. Under long-term, enormous loads, the reliability of the load-bearing performance and the ease of inspection and maintenance of the structure are particularly important, as they relate to the safety of the entire bridge. Therefore, researching a structurally sound cable-girder anchorage structure has significant practical value.

Modern cable-stayed bridges mainly consist of cables, beams, and towers. The stay cables connect the main girder and the main tower into a whole, forming a stable triangular geometry. The main girder and the load it bears are mainly transferred to the foundation through the stay cables and the main tower. Due to the enormous cable forces, the reliability of the cable-girder anchorage structure is crucial to the safety of the entire bridge and is a key design consideration.

For cable-stayed bridges with steel main girders, common cable-stayed girder anchorage structures include the cable-stayed saddle with anchor beam type, anchor box type, ear plate type, and embedded anchor pipe type. While each type has its merits, they also have significant shortcomings.

Because cable-stayed bridges are exposed to the natural environment for extended periods and bear alternating loads, they are highly susceptible to environmental corrosion, especially in areas containing high levels of corrosive substances such as SO42-, CO2, and Cl- (e.g., areas with severe air and water pollution). Once corrosion occurs in the bridge cable system, it will affect the safety and service life of the bridge, and in severe cases, can cause major safety accidents and huge economic losses. However, cable-stayed bridges are protected by sleeves, making it inconvenient to open them for direct monitoring of corrosion. Therefore, monitoring cable corrosion is an international challenge, and currently there is no effective method for evaluating cable corrosion and predicting its lifespan. Therefore, actively implementing cable corrosion prevention is of profound and significant importance, as prevention is better than cure.

In many cable-stayed bridge construction projects, a new type of cable duct sealing system is now used for waterproofing the cable ducts at the beam ends. Specific measures include: a rainproof cover and the installation of the new cable duct sealing system at the cable duct outlet; and the connection between the system and the cable body's PE casing using silicone and a sealing ring.

New Cable Duct Sealing System: Waterproofing and Corrosion Protection

1. Composition of the New Cable Duct Sealing System

The new cable duct sealing system mainly consists of a sealing airbag, a variable-diameter sealing bushing, and anti-corrosion sealant.

2. Working Principle of the New Cable Duct Sealing System

The sealing airbag is rolled and wrapped around the cable body and pushed into the cable duct opening. Compressed air or inert gas is used to inflate the airbag, causing it to expand under pressure. The main material forms a flexible waterproof isolation layer between the cable and the steel duct (variable-diameter bushing). The waterproof material on the outside of the airbag is compressed and extends by its own force, adaptively filling any small leaks. Once the inflation pressure reaches the rated value, the inflation hose is removed, completing the airbag sealing process.

WQBZ cable-stayed bridge duct sealing airbags have been successfully applied to numerous newly constructed cable-stayed bridges and major bridge repair projects, receiving high praise from construction and owner units. Construction personnel have reported that WQBZ cable-stayed bridge duct sealing airbags significantly reduce construction difficulty compared to polyurethane foam and grease-based sealants, shortening the sealing time for each cable duct and reducing the construction cycle. It perfectly solves the problems encountered when using traditional polyurethane foam and sealants for sealing!