Performance of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforced Polymer Strips
Abstract
:1. Introduction
2. Experimental Program
2.1. Test Parameters and Specimen Details
2.2. Test Measurements and Setup
2.3. Material Properties
3. Test Results
3.1. Cracking and Failure Mode
3.2. Load vs. Deflection Behavior
3.3. Shear Strength Contribution of Materials
3.4. Stirrup Strain
4. Discussion
5. Conclusions
- All the specimens showed ultimate failure due to strip fracture, except the specimens with side-bonded configuration in which bond delamination governed the behavior. Even with higher total amount of CFRP material, the contribution of the horizontal CFRP strips to shear and deflection in members with a bidirectional layout was negligible.
- Despite pre-cracking, the maximum shear capacity of the repaired members was slightly higher than that of the members strengthened without pre-cracking. The repaired specimens had a higher shear contribution of the CFRP strips than the pre-strengthened specimens.
- With identical amount of CFRP material, the members with higher amount of transverse reinforcement showed a higher shear contribution of the CFRP strips. This implies that the strengthening effect of CFRP materials can be maximized when the spacing of stirrups is reduced.
- The use of a bidirectional CFRP layout increased the efficiency of transverse reinforcement. A comparison of the results demonstrates that the measured stirrup strain at a fixed load level was well-distributed in members with bidirectional CFRP layout in members with unidirectional layout.
- The horizontal CFRP strips could not completely prevent the delamination failure of the vertical CFRP strips in members with side-bounded configuration. This indicates that CFRP anchors cannot be effectively replaced by horizontal CFRP strips in case of bidirectional layout.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Specimen Index | Cross-Sectional Details | fc’ (MPa) | CFRP Strip | Stirrup Spacing, s (mm) | |||||
---|---|---|---|---|---|---|---|---|---|
b (mm) | h (mm) | ff (MPa) | wf,v (mm) | sf,v (mm) | wf,h (mm) | sf,h (mm) | |||
200-C-00 | 300 | 500 | 36.8 | N/A | 200 | ||||
200-U-1F | 300 | 500 | 36.8 | 4600 | 100 | 200 | N/A | 200 | |
200-U-1F(R) | 300 | 500 | 36.8 | 4600 | 100 | 200 | 200 | ||
200-B-1F | 300 | 500 | 36.8 | 4600 | 50 | 200 | 50 | 200 | 200 |
200-B-1F(R) | 300 | 500 | 36.8 | 4600 | 50 | 200 | 50 | 200 | 200 |
100-C-00 | 300 | 500 | 36.8 | N/A | 100 | ||||
100-U-1F | 300 | 500 | 36.8 | 4600 | 100 | 200 | N/A | 100 | |
100-U-1F(R) | 300 | 500 | 36.8 | 4600 | 100 | 200 | 100 | ||
100-B-1F | 300 | 500 | 36.8 | 4600 | 50 | 200 | 50 | 100 | 100 |
100-B-1F(R) | 300 | 500 | 36.8 | 4600 | 50 | 200 | 50 | 100 | 100 |
200-U-1S | 300 | 500 | 31.8 | 4600 | 100 | 200 | N/A | 200 | 200 |
200-U-1U | 300 | 500 | 31.8 | 4600 | 100 | 200 | 200 | 200 | |
200-U-1F | 300 | 500 | 31.8 | 4600 | 100 | 200 | 200 | 200 | |
200-U-2F | 300 | 500 | 31.8 | 4600 | 100 | 200 | 200 | 200 | |
200-B-1S | 300 | 500 | 31.8 | 4600 | 100 | 200 | 100 | 200 | 200 |
200-B-1U | 300 | 500 | 31.8 | 4600 | 100 | 200 | 100 | 200 | 200 |
200-B-1F | 300 | 500 | 31.8 | 4600 | 100 | 200 | 100 | 200 | 200 |
200-B-1F (2) | 300 | 500 | 31.8 | 4600 | 100 | 200 | 100 | 200 | 200 |
Test Parameters | Transverse Reinforcement, D6 | Longitudinal Reinforcement, D25 | |
---|---|---|---|
First Test Series | fy (MPa) | 340 | 660 |
εy | 0.0023 | 0.0034 | |
E (MPa) | 148,000 | 195,000 | |
Second Test Series | fy (MPa) | 389 | 400 |
εy | 0.0024 | 0.0021 | |
E (MPa) | 159,000 | 195,000 |
Specimen | VACI (kN) | Vtest (kN) | Vtest/VACI | εs,max | εf,max | Failure Mode |
---|---|---|---|---|---|---|
200-C-00 | 179 | 360 | 2.01 | 0.0147 | - | Shear-compression |
200-U-1F | 235 | 473 | 2.01 | 0.0133 | 0.0075 | Strip fracture |
200-U-1F(R) | 235 | 519 | 2.21 | 0.0150 | 0.0101 | Strip fracture |
200-B-1F | 207 | 379 | 1.83 | 0.0137 | 0.0081 | Strip fracture |
200-B-1F(R) | 207 | 419 | 2.02 | 0.0109 | 0.0079 | Strip fracture |
100-C-00 | 226 | 356 | 1.57 | 0.0131 | - | Shear-compression |
100-U-1F | 282 | 560 | 1.99 | 0.0163 | 0.0127 | Strip fracture |
100-U-1F(R) | 282 | 581 | 2.06 | 0.0163 | 0.0126 | Strip fracture |
100-B-1F | 254 | 471 | 1.85 | 0.0143 | 0.0102 | Strip fracture |
100-B-1F(R) | 254 | 496 | 1.95 | 0.0157 | 0.0104 | Strip fracture |
200-U-1S | 212 | 304 | 1.43 | 0.0046 | 0.0062 | Strip delimitation |
200-U-1U | 213 | 332 | 1.56 | 0.0033 | 0.0073 | Strip fracture |
200-U-1F | 219 | 400 | 1.83 | 0.0040 | 0.0170 | Strip fracture |
200-U-2F | 269 | 542 | 2.01 | 0.0031 | 0.0103 | Strip fracture |
200-B-1S | 212 | 310 | 1.46 | 0.0075 | 0.0047 | Strip delimitation |
200-B-1U | 213 | 321 | 1.50 | 0.0094 | 0.0024 | Strip fracture |
200-B-1F | 219 | 414 | 1.89 | 0.0142 | 0.0103 | Strip fracture |
200-B-1F (2) | 219 | 429 | 1.96 | 0.0113 | 0.0095 | Strip fracture |
Specimen | Vc,test/Vc,ACI | Vs,test/Vs,ACI | Vf,test/Vf,ACI | Vf,ACI/Vs,ACI | Vf,test/Vs,test |
---|---|---|---|---|---|
200-C-00 | 1.96 | 2.13 | - | - | - |
200-U-1F | 1.66 | 2.29 | 2.63 | 1.18 | 1.35 |
200-U-1F(R) | 1.17 | 2.33 | 4.60 | 1.18 | 2.32 |
200-B-1F | 1.62 | 2.22 | 2.14 | 0.59 | 0.57 |
200-B-1F(R) | 1.86 | 2.17 | 2.56 | 0.59 | 0.69 |
100-C-00 | 1.24 | 2.04 | - | - | - |
100-U-1F | 0.24 | 2.41 | 5.44 | 0.59 | 1.33 |
100-U-1F(R) | 0.48 | 2.07 | 5.81 | 0.59 | 1.65 |
100-B-1F | 0.89 | 2.41 | 4.60 | 0.29 | 0.56 |
100-B-1F(R) | 0.86 | 2.41 | 5.62 | 0.29 | 0.69 |
200-U-1S | 1.79 | 1.08 | 0.76 | 1.00 | - |
200-U-1U | 1.58 | 1.24 | 1.57 | 1.03 | 0.71 |
200-U-1F | 2.32 | 1.11 | 1.34 | 1.03 | 1.30 |
200-U-2F | 2.42 | 1.76 | 1.59 | 2.06 | 1.24 |
200-B-1S | 1.88 | 1.05 | 0.67 | 1.00 | 1.86 |
200-B-1U | 1.91 | 1.20 | 0.67 | 1.03 | 0.64 |
200-B-1F | 1.18 | 1.66 | 3.60 | 1.03 | 0.58 |
200-B-1F (2) | 2.60 | 1.58 | 0.81 | 1.03 | 2.24 |
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Haroon, M.; Moon, J.S.; Kim, C. Performance of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforced Polymer Strips. Materials 2021, 14, 5866. https://doi.org/10.3390/ma14195866
Haroon M, Moon JS, Kim C. Performance of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforced Polymer Strips. Materials. 2021; 14(19):5866. https://doi.org/10.3390/ma14195866
Chicago/Turabian StyleHaroon, Muhammad, Jae Sang Moon, and Changhyuk Kim. 2021. "Performance of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforced Polymer Strips" Materials 14, no. 19: 5866. https://doi.org/10.3390/ma14195866