Bridge strengthening

Project Overview

The project is located on Huancheng Road in Taiyuan City, with an overpass span of 726 m. The net width of the bridge deck is 16.2 m, and the superstructure is prestressed box girder. The bridge was opened to traffic in the 1990s.

After a recent bridge inspection, it was found that the bearing capacity reserve of the bridge has declined seriously, which has begun to threaten the normal service of the bridge. It is determined by the government as an emergency rescue project, and must be dealt with immediately, and at the same time, it requires that the bridge deck be open to traffic during the reinforcement period. 

Therefore, it is planned to use prestressed carbon fiber plate reinforcement technology to complete the structural reinforcement.

Process Principle

(1) By applying prestress to carbon fiber plate, it can maximize the high tensile strength of carbon fiber material. The principle is similar to that of prestressed beam structure. Due to the prestress applied in advance, the material has a certain initial strain. After the second stress, it can improve the coordinated deformation ability of carbon fiber materials and concrete materials to improve the quality and effect of reinforcement.

(2) By applying prestress, decompression bending moment can be generated, which can offset a large part of the early load, improve the bearing capacity of the structure in the later period, significantly improve the crack resistance of the structure, and limit the appearance of new cracks, improve the overall rigidity and strength of the member, reduce the deformation of the bearing deflection.

(3) The deformation of the carbon fiber plate comes from two aspects, one is the deformation caused by the prestress, and the other is the deformation under the external load. The shearing deformation of the adhesive that shares the two parts of the deformation is distributed in the members. The two ends and mid-span positions of the adhesive can evenly distribute the shear deformation of the adhesive and prevent the brittle damage of the adhesive.

(4) For the proposed reinforcement structure, according to the mechanical performance and installation space of the engineering structure, the reinforcement position must be reasonably arranged, and the carbon fiber board coated with special epoxy glue should be used to pre-square the tension, repair the deformation and closed cracks of the component, and then paste the carbon fiber plate to the part of the bottom plate of the component to maximize the load-bearing capacity of the structure.

Bridge reinforcement materials

HM prestressed CFRP plate

HM-120cp carbon fiber plate adhesive

HM-200 chemical anchor bolt

Construction process

Scheme design-site construction preparation-beam bottom repairing and grinding-measurement lofting-drilling and planting reinforcement-anchorage installation-installation of carbon fiber board-stretched carbon fiber board-carbon fiber board coating-carbon board brush coating protection layer, anchoring at both ends of the anchor zone .

Conclusion 

The use of prestressed carbon fiber plate reinforcement technology can be widely applied to many reasons, such as damaged concrete structure, corroded steel bar, load lifting, standard improvement, improper design and construction, changes in use function, etc. In order to extend and improve the service life and capacity of the bridge structure as much as possible, improve the bearing capacity of the structure, and enable the bridge structure to exert higher service requirements, the above bridges must be reinforced and reinforced as necessary. Considering that the use of prestressed carbon fiber plate reinforcement technology has the advantages of simple construction and low technical threshold, only the construction personnel need to have a certain prestress application technology. In addition, the entire construction process does not require the support of large mechanical equipment, and can be completed using only various types of small equipment, such as electric drills, rhinestones and jacks. During the bridge reinforcement construction, since there is no need to close the traffic, it will not affect the normal passage of the bridge deck and will not cause congestion pressure on the local traffic. This article takes case analysis as the main method and summarizes the relevant technologies on the reinforcement of prestressed carbon fiber plate. It has been proved by practice that the use of prestressed carbon fiber reinforcement method at the bottom of the beam can significantly improve the bearing capacity of the bridge, and the construction process has a high cost performance, which is worth further promotion .