CFRP wrap has high tensile strength and fatigue strength in the direction of CIS fiber, and the compression and shear strength are relatively low, so it is mainly adapted to the reinforcement of the tensile region of the concrete structural members, but the CFRP can be circular or U around the concrete members, so it can also be used for the compression of concrete members or shear reinforcement.

Main application forms of FRP strengthening

Reinforcement of cantilever structure

For the cantilever structure, the common problems are the insufficient reinforcement of the root or the serious subsidence of the steel bar position, which leads to the insufficient bearing capacity, the structure cracking or the lack of structural stiffness, and the excessive deflection and so on. Carbon fiber reinforcement is generally used to paste carbon fiber fabric along the force direction at the top of the component. Outside the reinforcement area, enough anchorage length should be left at both ends.

One way slab strengthening

Because of the insufficient reinforcement of the floor slab, or the reinforcement of the corrosion damage of the steel bar, it can be strengthened by the method of sticking carbon fiber cloth, which can effectively improve the bending bearing capacity and stiffness of the plate, prevent the further expansion of the cracks, restore the overall performance of the cracked slab and reduce the later deflection of the plate.

For the positive bending moment reinforcement of the one-way continuous slab, the carbon fiber fabric  is usually pasted on the floor, and the direction of the sticker is the same as the force direction of the plate. If it is the short span of the plate, it can be stickup with a full plate and can be stickup at a certain distance. The length of the paste is determined according to the calculation results, and the length of the paste is generally taken as the net span of the plate.

If the bearing capacity of the anti negative bending moment is insufficient, the carbon fiber fabric is pasted on the plate, and the direction of the paste is the same as the force direction of the plate. The bonding length needs to consider the needs of the anchorage.

Two-way slab reinforcement

For large span concrete two-way slab, the CFRP sheets should be strengthened at the bottom of the slab. When the bearing capacity of the building is negative, the reinforcement method is the same as that of the one-way plate.

Beam strengthening

The frame beam is usually able to improve the bearing capacity of the cross section and the positive cross section in the beam span by sticking carbon fiber cloth, while the negative bending moment reinforcement at both ends is more difficult, and other reinforcement methods are needed.

For strengthening the beam strengthening of the cross section, the method of sticking carbon fiber cloth and carbon fiber sheet on the bottom of the beam can be adopted. After strengthening, the stiffness of Liang Kangwan is improved, especially the crack resistance stiffness has been greatly improved.

For the insufficient bearing capacity of the cross section at both ends of the beam, it can be strengthened by sticking "U" carbon fiber on the side of the ring beam.

Column strengthening

For columns subjected to axial pressure, CFRP is usually enclosed by a four week circular enclosure when the CFRP is strengthened to improve its bearing capacity or to improve its resistance. The direction of the fiber is perpendicular to the column. The number of CFRP sheets is generally 1-2 layers, and the number of layers is more than 2 layers. Increasing the number of layers has no obvious effect on the further improvement of the bearing capacity.