Home    Industry News    [case] easy to use! Formula for prolonging life of cable rod system -- special maintenance and prolonging life of hanger rod system of Xinguang Bridge

[case] easy to use! Formula for prolonging life of cable rod system -- special maintenance and prolonging life of hanger rod system of Xinguang Bridge

Hits: 3897126 2020-05-04

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Site operation video of Xinguang Bridge
1、 Project overview
Xinguang Bridge was first built in January 2004, the main bridge was completed at the end of September 2006, and Xinguang expressway was opened to traffic in November, which is one of the geographical indications of Guangzhou.
After more than 10 years of operation, the regular inspection report shows that various parts of the bridge have some diseases. In order to prevent these diseases from continuing to develop and affect the structure of the bridge, the management unit of Xinguang Bridge decided to carry out special maintenance and life extension for the suspension system of the bridge.
The specific work includes: inspection of upper and lower anchor heads of suspenders, derusting and anti-corrosion, derusting and anti-corrosion of anchor head protective cover, inspection of HDPE sheath and hot-melt repair of damaged parts, wrapping PVF tape on the surface of HDPE sheath of suspenders, removal of accumulated water in cable ducts, filling of polyurethane grouting materials, removal and replacement of damping rubber blocks, etc. The project has the characteristics of small volume, short construction period, many projects and miscellaneous technology.
2、 Highlights of construction measures of this project
1. High altitude work basket
According to the needs of removing the HDPE sheathed light belt of suspender, repairing the suspender and wrapping, a special U-shaped construction basket suitable for the suspender of arch bridge is adopted, and a special limit wheel is designed for the basket, so as to improve the wind resistance stability of the basket and the reverse rotation stability of the wrapping machine during the construction of PVF belt. PVF with wrapping operation is a special wrapping machine tool specially developed according to the construction characteristics of suspenders. It has the characteristics of light weight, easy entry, convenient use and high construction efficiency. Fig. 1 construction drawing of suspender wrapping
2. Baibian beam bottom construction platform
For the maintenance of the lower anchor head and the repair of the concrete cracks at the bottom of the beam, a modular construction platform is adopted. The construction platform is a combination of Bailey structure and truss structure. The flange + high-strength bolt is used to connect the pieces of the frame. The foot wheel with direction lock is used to move in all directions for the bridge deck part, which can be freely combined according to different use conditions. The structure of the construction platform is light, which can be carried out in multiple working faces at the same time. The working faces do not interfere with each other, which greatly improves the construction efficiency, and solves the problem that the platform at the bottom of the beam of Xinguang Bridge is difficult to pass the navigation mark directly.
Fig. 2 working condition of overhanging lower anchor head maintenance
According to the inspection and maintenance needs of the beam bottom crossbeam, small longitudinal beam and bridge deck surface defects of Xinguang Bridge, the modular combined platform can be lifted 42 meters as a whole to meet the requirements of regular inspection and maintenance. The platform is made of aviation grade aluminum, which is light and convenient to use.
Fig. 3 modular assembly of hanging basket
3、 Measures for disease maintenance and life extension
1. PE repair
The main reasons for the damage of PE protective layer of Xinguang Bridge are as follows: (1) PE sheath is exposed to the air for a long time, and it is exposed to ultraviolet radiation, rain water washing, even freezing, harmful gas corrosion. (2) During the installation of suspender and the construction of adding light belt, the protection measures for the cable body are not enough, and the cable body is damaged to a certain extent. The main construction process of PE damage maintenance is as follows: ① carefully clean the wound and prepare PE strips of the same color. ② Use special tools for hot-melt PE repair. ③ After repair, polish to restore PE layer to original thickness.
2. Delay the aging of PE sheath
When the suspender is stressed, the outer HDPE sheath will also be subject to the corresponding tensile stress. Under the condition of stress, the HDPE sheath is easy to accelerate aging due to long-term sun and rain, which is manifested as a large area of cracks on the surface of the suspender sheath. The continuous development of cracks will lead to the sheath cracking and water inflow, loss of protection function, and affect the structural safety of the bridge. In order to slow down the continuous aging of HDPE sheath, it is necessary to shield the surface of HDPE sheath. By winding anti-aging wrapping tape, we can prevent the direct sunlight and the erosion of acid rain, so as to delay the aging speed of the sheath, improve the protection life and extend the replacement time.
3. Maintenance of anchor head protective cover and cable conduit
The protection cover of the anchor head and the ponding of the cable duct are also the prominent diseases of Xinguang Bridge. Due to the poor sealing effect of the protection cover of the anchor head and the waterproof cover of the cable duct, the transpiration and condensation effect inside the suspender and the lack of the bolts and other reasons, there are a lot of ponding inside the anchor head and the cable duct. The anchor head is seriously rusted, which seriously affects the safety of the suspender. We solved the problem of anchor head protection by removing rust, coating sealing wax and adding protective film. By removing the water inside the cable conduit, pouring polyurethane grouting material into the cable conduit, replacing the sealing ring and other measures, we removed the cable conduit related diseases.
4、 Conclusion
The special maintenance and life extension project of the suspender system of Xinguang Bridge lasted for three months from the first ten days of October 2019 to the first ten days of January 2020. Under the premise of scientific, standardized and safe operation, the maintenance and life extension construction of the bridge was successfully completed with high quality. Part of the maintenance content of Xinguang Bridge is simply introduced here. If you are interested in the platform lifting process, wrapping construction details and process requirements, shock absorber replacement and other content, please contact us (wechat Mobile: 17728195516), and we can further communicate. About the author
Lin Yangzi, Dr. hahaha
He majored in bridge and tunnel engineering at Harbin University of Technology
Professor level senior engineer, first level registered structural engineer
Excellent highway engineer of Guangdong Province, Inspection Engineer of Ministry of Communications
More than ten years of sharpening a sword, focusing on cable bridge maintenance
He published a monograph on special detection, maintenance and reinforcement technology of bridge cable system;
Completed many provincial and ministerial scientific research projects related to bridge and cable maintenance, and won many science and technology awards of China highway society;
The company has developed advanced equipment such as cable climbing robot, corrosion and broken wire detection system, and obtained many related patents;
The project of special inspection, maintenance and reinforcement of hundreds of cable system bridges has been completed.
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