Bridge reinforcement engineering

Introduction

The overall level of traditional reinforcement technology is relatively backward, the construction method and process are complex and more equipment is required, which is limited by factors such as site.

As an emerging technology, carbon fiber reinforcement method has the advantages of convenient construction, corrosion resistance, light weight, high structural strength, and no significant increase in structural size. In addition, through technical analysis of material prices, construction operations and maintenance costs, we can find that carbon fiber reinforced concrete has excellent cost performance, advanced technology and high technology content. The technology has good technical and economic benefits, environmental benefits, and social benefits, and has strong competitiveness.

Therefore, this technology has gradually become the mainstream of reinforcement technology. Combined with the practical experience of using carbon fiber to reinforce and reinforce the East Wei Gezhuang Bridge, the materials, construction technology and application performance were analyzed.

Project Overview

East Wei Gezhuang Bridge is located in Xianghe County, Langfang City, Hebei Province. Completed in 1971, it straddles the Chaohe River. The bridge has a length of 229.64m, a width of 11.8m, a total of 16 holes and an aperture of 14.1m. The upper part is a T-shaped beam, and the lower part is a pile-type abutment. The project widened and strengthened the bridge, and increased the load standard from steam -13 tons, hanging -20 tons to steam -20 tons, hanging -100 tons. Among them, carbon fiber is used for T-beam reinforcement, and the detection effect is good.

Brief introduction of carbon fiber reinforcement technology

Carbon fiber reinforcement is a brand-new reinforcement technology that effectively solves the defects in reinforcement methods such as large concrete sections. Carbon fiber is very thin in form, 100 times thinner than human hair, and its density is less than that of steel, but its strength is greater than steel. In use, the maximum tensile strength of carbon fiber can reach 9 times that of steel. This high-strength, high-elasticity and corrosion-resistant feature is well applied in construction and also has flexibility. Carbon fiber can be processed, even after the surface is reinforced, there is an unbalanced area, it can be adhered as a whole. In addition to these advantages, carbon fiber is also a lighter-weight material. After pasting, the weight per square meter is less than 1kg and the thickness is less than 1mm, and the original structure size and weight will not be increased after reinforcement. Compared with the traditional reinforced concrete section or reinforced steel reinforced concrete, carbon fiber construction is simple, reduces the space utilization rate, no need to reinforce the on-site fixed facilities, and the construction quality is higher. During construction, the structure size and thickness will not be increased, and the durability is good. Application of this method of construction reinforcement can increase the service life of buildings, so this material is used in many industries.

Carbon fiber reinforced materials 

CFRP Strengthening System

Externally bonded carbon fiber reinforced polymer(CFRP) composite system for strengthening masonry, concrete, steel and wooden structures.

Horse CFRP Wrap

Horse CFRP Fabric

Horse CFRP Sheet

Horse Carbon Fiber Primer

Horse Levelling Adhesive

Horse Carbon Fiber Adhesive

Horse CFRP Strip Adhesive

Horse Carbon Fiber Strip

Carbon fiber reinforcement

The flexural reinforcement of the main beam of the T-beam of the bridge uses 18×1800 (cm) and 18×400 (cm) carbon fiber sheets for the bending moment compression of the main beam spanning the mid-beam. A 12cm wide U-shaped hoop is provided at each end of each layer to fix the carbon fiber sheet.

The shear reinforcement scheme of the main beam of the T-beam of the bridge begins to be strengthened near the fulcrum of the fulcrum. A U-shaped outer hoop with a carbon fiber sheet width of 20 cm is added, and a main beam is provided with 12 channels. The webs at the end of each main beam are made of U-shaped transverse outer cuffs with a width of 20 cm.

Carbon fiber reinforcement construction process

The construction process of carbon fiber reinforcement and reinforcement is as follows: surface treatment of the beam member → base treatment → primer → scraping and leveling material →  a layer of impregnating resin → bonding carbon fiber sheet → applying a layer of impregnating resin → maintenance → protective coating

Contrast analysis and comparison of carbon fiber reinforcement

The test data before and after the bridge reinforcement found that the dynamic and static load data of the bridge strengthened by the carbon fiber reinforcement technology were significantly improved, and the bridge reinforcement effect was obvious. The construction process of carbon fiber reinforcement and reinforcement technology is simple, can be operated with small electric tools, requires fewer personnel, has a short construction period, and has a fast progress. It can be constructed without interrupting traffic and is less affected by the environment. Thereby greatly shortening the construction period of off-hand construction, which has very good social and economic benefits. Using this method can greatly increase the service life of the building and reduce the cost of reinforcement. Therefore, it is suitable for bridge reinforcement and repair of bridge cracks where the damage of the bridge body is not serious, the construction period is short, and the traffic volume is large.

Conclusion

With the progress of the times, science and technology, and the development of China's transportation industry, some old bridges have gradually failed to meet the needs of modern transportation development due to long-term disrepair or increased load, and implement the national environmental protection and energy-saving requirements. Reinforcement has prolonged its service life, so the maintenance and reinforcement of the old bridge is very large. At the same time, due to the limitations of the traditional reinforced concrete reinforcement method, carbon fiber reinforcement with its excellent performance will definitely play a huge role in the future bridge reinforcement.