Any method of reinforcement is not omnipotent. Carbon fiber retrofitting is carried out on the basis of the original component. The size of the original structure, the reinforcement and the strength of the concrete limit the extent of the function.

Simple supported beam reinforcement as an example:

- BXH rectangular beam with a tensile bar As and a compression bar As'. How much flexural ability can be increased by carbon fiber reinforcement?

In the case of cross section and compression bar is certain, with the increase of tensile steel components, the height of compression zone is increasing, but the maximum does not exceed ξbh0（ξb the relative height of compression zone boundaries); so the components can withstand the maximum bending moment calculation is not greater than Mb. [Mb=fcb bh0 (h0-0.5 b) +fy'As (h0-as')]

Of course, if combined with other reinforcement methods, such as enlarging the section and steel plate bonding reinforcement, the bearing capacity can be increased to a greater extent.