Repair of reinforced concrete beams

Project Overview

Due to the decoration needs of the hotel, after dismantling the old decoration works, there were cracks in about ten beams and some floors. Failure modes include bending crack failure, bending shear crack failure and abdominal shear crack failure. The failure of abdominal shear cracks is a mixed failure mode. There is a yield of the steel bars, but the failure occurs suddenly due to the horizontal tearing of the concrete protective layer under the horizontal position of the steel bars. The failure of abdominal shear cracks must be regarded as premature high-brittle failure in the form of shearing and spalling of the concrete in the horizontal position of the reinforcement, and there is no sign of bond failure before the failure, and no yield of the main bars.

After demonstrating plans and comparing economic and technical feasibility, it was decided to use carbon fiber reinforced polymer(CFRP) for reinforcement. When the carbon fiber cloth is used to reinforce the concrete structure, the carbon fiber cloth is pasted on the surface of the member through the matching bonding material, so that the carbon fiber cloth can bear the tensile force, coordinate with the deformation of the concrete, and bear together.

Carbon fiber reinforcement method for concrete structural members

<1> Paste the carbon fiber fabric in the tensile zone of beams and slab members for flexural reinforcement, and the fiber direction is consistent with the tensile direction of the reinforcement.

<2>Using U-shaped paste to strengthen the beam member by shearing, the fiber direction is perpendicular to the axial direction of the member.

Reinforcement construction steps

1.Construction preparation

2.Concrete surface treatment

3.Formulate and apply primer

4.Preparation of leveling materials and leveling of uneven areas

5.Formulate and applying impregnating adhesive

6.Externally bonding carbon fiber cloth

7.Surface protection

Conclusion

The project was completed in December 2003, without any quality problems. Carbon fiber is a light-weight, high-strength, emerging construction material with excellent construction effects.