Carbon fiber reinforced polymer(CFRP) wrap can be successfully used for concrete structure, seismic shear and flexural strengthening. But it should be pointed out that because many inherent characteristics of CFRP reinforcement structure, many concrete structures are not suitable for strengthening with carbon fiber, so it is necessary to analyze their applicability.

So in which cases are not suitable for reinforcement by CFRP fabric?

1, Stiffness problem

When the concrete floor and roof structure are affected by the lack of rigidity, the deformation is too large and the cracking is serious. It is not suitable for strengthening the reinforcement with carbon fiber fabric.

For beams, slabs and other transverse members, when carbon fiber is used for reinforcement, the progressive effect of carbon fiber on structural stiffness is less than 10%, or no progress has been made.

2.The scope of application of carbon fiber flexural reinforcement

When the concrete structure is due to the poor flexural capacity, the damage shape of the reinforcing structure depends on the reinforcement condition of the original structure on the one hand, and on the other hand, it depends on the amount of carbon fiber.

Carbon fiber is more used. At the time of damage, the marginal concrete of the compression zone is crushed, the tensile steel is submissive, and the carbon fiber strain is very low.This situation is not suitable because of the large amount of carbon fiber and low utilization rate of strength.

3.Torsional problem

Because of the use of carbon fiber reinforcement, a crack has been formed, the crack spread has been concluded; on the other hand, because the ultimate strain of carbon fiber is more than 10000 mu epsilon, while the ordinary steel strain less than 2000 mu epsilon is resigned, if more than 4000 were obtained when the strain applied to the concrete crack width start, will start to surface development, structure was close to that of the damage, but at the moment the carbon fiber can reach the stress is very low, so the carbon fiber reinforcement torsion effect is necessary after further discussion.