Research content: Test of reinforced concrete beams strengthened with 9 carbon fiber sheets

The purpose of the study: the influence and effect of the amount of carbon fiber cloth on the bending performance of reinforced concrete beams.

The test beams are simply supported beams with a rectangular cross-section, divided into two groups. The cross-sectional dimensions are b * h = 100mm * 200mm, span l = 2200mm, and net span l0 = 2000mm. Group Ⅰ beams: the longitudinal reinforcement is 2 @ 8, the stirrup is Ф6 @ 100, and the stand-up reinforcement is 2 @ 4. Group Ⅱ beam: longitudinal reinforcement, 2 @ 10, design reinforcement ratio 0.92%, hoop reinforcement in shear span area and pure bend section are Ф6 @ 100 and Ф6 @ 200 respectively, and stand-up reinforcement is 2 @ 4.

Reinforcement situation about beams and main test results

Test Conclusions:

1. When reinforced concrete beams are strengthened with carbon fiber cloth, the average strain of the section still meets the assumption of flat section.

2. It is effective to use carbon fiber cloth to strengthen the reinforced concrete bending members. After the carbon fiber cloth was affixed, the bending capacity of the test beam was significantly improved, and the ultimate bending capacity was significantly improved.

3. There is a problem of the use efficiency in the application of carbon fiber cloth. The experimental study found that the same amount of carbon fiber cloth was slightly better than the whole strip for the reinforcement effect.

4. The bending bearing capacity of the component increases with the increase of the amount of carbon fiber cloth. When the number of layers of carbon fiber cloth is less, the increase is relatively large. Due to the use efficiency, the increase rate decreases with the increase of the number of layers of carbon fiber cloth.

5. Increasing the amount of carbon fiber cloth will change the failure form of the bending member from the damage caused by the carbon fiber being broken to the crushed concrete. At the same time, because carbon fiber is a completely elastic material, its joint work with the steel bar will weaken the plastic deformation of the steel bar to improve the ductility of the component. When the amount of carbon fiber cloth is excessive, the ductility of the component is reduced.

6. The deflection of the test beam pasted with carbon fiber cloth is smaller than that of the unreinforced beam, indicating that the use of carbon fiber cloth increases the bending stiffness of the member.