Many areas are prone to earthquakes, and the city is densely populated. Some old buildings have the problem of inadequate seismic performance in the initial design. Once a strong earthquake occurs, it will lead to serious structural damage, and even a large number of buildings collapse. 

For example, the economic losses caused by the earthquake in Fenchuan are as high as 845.1 billion yuan. Over the past few years, Sichuan has spent 1.7 trillion yuan on post-earthquake reconstruction and development. Therefore, it is urgent to reinforce and repair these old buildings. 

In recent years, there have been many carbon fibre used for reinforcement. At the same time, the reinforcement technology has been greatly improved. It is not only convenient to construct, but also can improve the bearing capacity, deformation capacity and seismic performance of the structure, prolong the service life, and has been widely used in the field of repair and reinforcement.

Reinforcement Principle of Carbon Fiber Fabric:

By using the technical method of strengthening and repairing concrete structure with carbon fiber sheet, the carbon fiber sheet is pasted on the surface of concrete with adhesives, which has the advantages of strengthening and seismic strengthening. Therefore, the CFRP reinforcement method is widely used in the floor, column, beam, wall reinforcement construction of buildings, and even can be used in the reinforcement of large-scale projects such as bridges, tunnels and so on.

Characteristic of Carbon Fiber Fabric :

1) It has high strength and can be flexibly used for flexural, shear and axial compression reinforcement in complex situations.

2) High strength, light weight and small thickness;

3) Good corrosion resistance, alkali resistance, acid resistance and corrosion resistance;

4) It has excellent durability and excellent anti-fatigue ability.

5) Uniform tension and no distortion;

6) It is easy to construct in different environments.

The transverse wrapping of CFRP sheets with 200 mm spacing makes the direction of the fibers parallel to the ground, which can produce circumferential restraint effect and reduce the compression coefficient of the columns, thus enhancing the compressive capacity of the columns and improving the ductility of the columns.

This kind of damage reinforcement method has remarkable reinforcement effect. The reason why CFRP circumferential wrapped columns can improve the ductility of columns is that CFRP wrapped columns can restrain the deformation of high-strength concrete columns very well, and the restraint effect of CFRP wrapped columns on concrete is more direct and efficient than that of stirrups.

When CFRP is used to reinforce damaged concrete beams, CFRP can not only effectively restrain the extension of cracks and the development of crack width. And when there are more cracks in the beam, it can still work normally, and it can enhance the integrity of the beam and improve the bearing capacity of the beam.

Reinforcement of oblique section of reinforced concrete flexural members: It is effective to use carbon fibers to improve the shear capacity of concrete members. After bonding CFRP, the cracking load and shear load force of the beam can be significantly improved. Among them, the improvement of shear capacity is particularly significant. Carbon fibers improve the shear capacity and the mechanism is similar to stirrups. Therefore, to improve the shear capacity of reinforced concrete beams, colleagues can also significantly improve the deformability of members and increase the ductility of members.

In recent years, the structure is strengthened by pasting carbon fiber sheet. The structure is under reasonable stress, which achieves the purpose of safety, economy, reliability and applicability. With the improvement of living standards, people's requirements for the safety, applicability and durability of buildings are gradually increasing, and the repair and reinforcement of existing structures has also attracted extensive attention of the engineering community. There are many earthquake disasters and high requirements for seismic performance of structures. Therefore, the reinforcement of buildings and the repair of damaged structures are also the main research directions of structural engineers. Therefore, the development and promotion of new materials and technologies, such as fiber reinforced concrete, have been generally recognized that carbon fibers are widely used in the reinforcement of damaged reinforced concrete structures, which has a positive role in promoting the development of reinforcement projects.