Repair of Corrosion-Damaged Reinforced Concrete Beams

Project overview

The pharmaceutical factory was built in 1984, because of corrosion of corrosive gases for a long time, three thin abdominal beam understring concrete and steel are seriously corroded. It causes cracking, crisp and exfoliation of the protective concrete, rusted and exfoliation of the lower string, weakened section of the steel bar, endangering the safety of the structure and affecting the production mood of the workers.

FRP composite system is selected for reinforcement, which can prevent corrosive gas from eroding and prolong the service life of the beam.

The basis for FRP composite strengthening

The pharmaceutical factory to provide workshop drawings.

The corrosion situation of roof.

The actual testing strength of thin web girder.

The technical specification for reinforced concrete structure.

Precondition for FRP composite strengthening

First, we use rebound method to detect thin web beam concrete. After testing, the actual strength of the concrete is C30.

According to the design drawings, the corrosion of the concrete and reinforcement in the field, the tensile strength grade of the lower chord is considered. For this reason, 2 layers of 300mm wide carbon cloth are attached to the bottom of the lower chord and both sides (the width of the lower chord of the thin abdominal beam is 200mm). After reinforcement, it is equivalent to increasing 46% of the surface product of the original reinforced bar, making up for the reduction of the cross section caused by the corrosion of the original steel bar, and the bearing capacity of the component is obtained. Moreover, the overall strengthening, reinforcement ratio: ρmin≤ρ≤ρmax  can satisfy the requirement of use.

Conclusion

From the FRP reinforcement up to now, corrosive gases have not eroded.

Carbon FRP is a advanced materials for structural strengthening.