The structural strengthening of concrete structure can be divided into two categories: direct reinforcement and indirect reinforcement.

Direct reinforcement is a direct needle for strengthening the bearing capacity of structural members or joints. According to the actual situation, the reinforcement method of enlarging section, replacing concrete, external stick steel plate, sticking steel jacketing plate and sticking fiber reinfroced polymer(FRP) composite can be selected.

The indirect reinforcement is aimed at the overall layout of the structure. By reducing or changing the reinforcement of the internal force of the component, the external prestressing reinforcement method or the additional fulcrum reinforcement method should be selected according to the actual situation of the engineering.

In a certain range of application, the direct reinforcement method is more flexible and easy to deal with all kinds of reinforcement problems. The indirect reinforcement method is simple and reliable, and it is easy to disassemble and replace in the future. It can also be used in the history of reversible requirements and the emergency reinforcement of cultural relics.

The main reinforcement methods of concrete structure can be summed up into three types according to their characteristics, namely, “concrete method”, “external bonding reinforcement” and “mechanical strengthening method”.

“Concrete method” refers to the reinforcement method of strengthening the concrete structure or reinforcement by increasing the section of the concrete component, improving the strength grade of concrete or improving the quality of the concrete construction. The emphasis of the reinforcement is concrete, mainly including the reinforcement method of enlarging the cross section and the replacement of the concrete.

The “external bonding strengthening method” refers to the reinforcement methods for improving the bearing capacity and seismic performance of the steel, steel plate or fiber composite material outside the original concrete components by grouting or structural glue, including the external bonded steel (outer steel jacketing) reinforcement method, the bonded steel plate reinforcement method and the bonded fiber reinfroced polymer (FRP) composite  reinforcement method.

“Mechanical strengthening method” refers to the application of the principle of building mechanics, by changing the way of force transmission or providing reverse bending moment to remove, reduce or reduce the internal force, so that the original concrete members meet the loading requirements of the reinforcement method, and the mechanical reinforcement method includes the addition of the fulcrum reinforcement method and the external prestressed reinforcement method.