Bridge Reinforcement

The bridge is located on a national highway in Fujian Province. The design load is car-20 and trailer-100. The upper structure adopts 1m×13m reinforced concrete cast-in-situ hollow slab. The length of the bridge is 28.4m. The abutment adopts U-shaped abutment with enlarged foundation. The full width of the bridge is 9.4m, and the lateral layout of the bridge deck is: 0.2m (guardrail) + 9.0m (carriageway) + 0.2m (guardrail). The upper structure of the bridge is: hollow slab girder, simple bearing. The lower structure of the bridge is: gravity abutment and enlarged foundation. The bridge deck system is: cement concrete pavement with hidden seams.

According to the special inspection of the bridge, there are more than 179 cracks in the bottom of the hollow slab, and the width of the cracks ranges from 0.03 to 0.13mm. Among them, longitudinal cracks are 18.1m (total of 2), diagonal cracks are of 1.6m (total of 2), and transverse cracks are of 100.8m (total of 175); the dynamic and static load tests show that the bearing capacity of the bridge meets the original design requirements.

The early construction of the bridge was restricted by factors such as the load standard, construction technology level and construction technology at the time. Under the current heavy-duty vehicle traffic, the upper structure is prone to cracks and other diseases.

Prestressed steel strand reinforcement and prestressed carbon fiber board reinforcement are active reinforcement technologies. If considering the use of these two reinforcement technologies to improve the bearing capacity of the bridge, the construction process requirements are relatively strict. If the prestressing construction is not in place, it may not be able to improve the bearing capacity of the bridge, and even cause damage to the original structure and reduce the bearing capacity. . However, the passive reinforcement of pasted steel plates will increase the weight of the structure and only slow down the development of cracks. Finally, the carbon fiber grid was used to strengthen the bridge.

Carbon fiber mesh is a brand-new composite material with high-quality characteristics such as light weight and high strength. The solid bonding and joint stress of the interface between the carbon fiber mesh composite layer and the concrete component are mainly achieved through the matching high-strength mortar with good crack resistance and no shrinkage. It has the effect of improving the rigidity and bearing capacity of concrete components and enhancing the overall crack limiting capacity of concrete components.

After the fiber composite layer is reinforced, the crack width is significantly reduced. After reinforcement, the bearing capacity of the structure is improved.