Bridge Retrofitting

1. Project Overview

When a bridge was inspected, it was found that the bridge was deflection and deformation, the bridge's bearing capacity did not meet the requirements, and the structural safety reserve was insufficient. In order to eliminate potential safety hazards and prevent bridge accidents, it was decided to carry out reinforcement treatment.

2. Main diseases

The insufficient bearing capacity of the bridge seriously affects the safety performance of the bridge. At the same time, the loss of prestress of the prestressed steel bar is too large, resulting in insufficient bridge inverted arch value. Under long-term load, the concrete in the tension zone at the bottom of the beam is prone to cracks, destroying the integrity of the bridge and threatening the safety of the bridge.

3. The solution

Taking into account the insufficient bearing capacity of the bridge and the increase in the inverted arch value, it is necessary to adopt a reinforcement method with high utilization efficiency of the reinforcement material. At the same time, in order to achieve the best reinforcement effect, it is finally decided to stick two prestressed carbon fiber plates longitudinally at the bottom of each beam. The size of the carbon plate is 11100mm×50mm×3.0mm, the ultimate tensile stress is ≥2400KN, and the ultimate tensile strength is 360KN. . The tensile stress of this project is 666.7MPa, and the tensile force is 100KN.

4. Construction difficulties

1. The bridge's bearing capacity is low, the bearing load is high, and the requirements for the strength of the carbon plate are high;

2. The bridge has a high traffic flow, long-term dynamic load, and the prestressed carbon plate reinforcement system requires high fatigue resistance;

3. There are dense steel bars at the bottom of the bridge, and the layout of the steel bars is complicated and different from the original construction drawings, making it difficult to drill;

4. The situation of the fixed end of the prestressed carbon plate is complicated, and the integral steel block is used for installation, and the two prestressed carbon plates in each beam are located on the same steel block;

5. The steel block at the fixed end of the anchor needs to be grooved, which will cause a certain disturbance to the original structure;

6. The anchoring end has high requirements for the position and verticality of the planting bar hole, and the drilling depth must meet the standard;

7. Slotting leads to a small gap between the carbon plate and the original structure, which requires high colloid performance;

8. The on-site construction environment is complicated, the working space is severely restricted, and the construction method is demanding.

5. Construction results

In view of the complex construction environment and serious bridge diseases, HORSE senior technicians immediately set off to the project site for construction guidance. Comprehensive design documents and on-site actual construction environment, detailed guidance for drilling and slotting, etc., the project was successfully completed, and witnessed by the owner and the supervisor, it was confirmed that the tension error was far below the specified value. The bridge was recently completed, and its bearing capacity and safety reserves all met the requirements.

Through this project, we can see that the reinforcement effect provided by the pre-stressed carbon plate on the bridge's bearing capacity and insufficient pre-stress is obvious, and at the same time it cannot be replaced by other methods. HORSE prestressed carbon panels are continuously contributing to the safety of building structures through more and more projects.