The concrete-filled steel tube structure is more and more widely used in civil engineering. Filling the concrete with steel tubes can form a strong combined structure, which is often used in bridge pier and column structures. The appearance of carbon fiber reinforced sheet provides an excellent material for the reinforcement of this structure.

The carbon fiber sheet was reinforced in the tension zone of the concrete-filled steel tube member to achieve good results, and the bending strength of the member was significantly improved.

1) Strengthen the concrete-filled steel tube beam with carbon fiber reinforced polymer sheet. With the increase of the number of adhesive layers, the bending resistance will be strengthened.

2) Compared with unidirectional fiber sheet, the addition of U-shaped hoop perpendicular to it has better reinforcement effect. The U-shaped hoop can be a single fiber strip or a single piece of fiber cloth. The U-shaped hoop effectively restrains the opening and shedding of the reinforcing fibers.

3) When reinforced along the beam length of 100% or 75%, the reinforcement effect is not much different, and the bending strength increase value is 26%~27%.

4) After artificially making a gap in the beam, and then strengthening it, when the same layer of carbon fiber cloth is used for reinforcement, the reinforcement effect is similar to that of the uncut beam (increased by 39% and 38%). At this time, the steel pipe has withdrawn from the force, and the carbon fiber cloth alone provided bending resistance.

5) After reinforcing the CFST beam with carbon fiber cloth, its energy consumption capacity will greatly increase. When two layers of carbon cloth are pasted in the tension zone, the energy consumption is increased by 7.7%. If another layer of vertical carbon fiber cloth is added, the energy consumption can reach 18.4%.