Influence of Compressive Strength of Concrete on Shear Strengthening of Reinforced Concrete Beams with Near Surface Mounted Carbon Fiber-Reinforced Polymer
Abstract
:1. Introduction
2. Experimental Investigation
2.1. Materials
2.1.1. Concrete
2.1.2. Steel
2.1.3. Carbon Fiber Reinforced Polymer (CFRP)
2.1.4. Epoxy Resin
2.2. Beams Geometry and Reinforcement Details
2.3. Details of Specimens
2.4. Construction of Beams
2.4.1. Concrete Casting and Curing
2.4.2. CFRP Installation
2.5. Test Setup
3. Theoretical Considerations
3.1. Theoretical Capacity According to the ACI 440.2R-17
3.2. Finite Element Analysis (FEA)
3.2.1. Parts
3.2.2. Materials Definition
3.2.3. Sections
3.2.4. Meshing
3.2.5. Interactions and Constraints
3.2.6. Boundary Conditions and Test Setup
4. Results and Discussion
4.1. General Behavior and Failure Modes
4.2. Experimental Load-Deflection Curves
4.3. Experimental Ultimate Loads
4.4. Theoretical Results
4.5. FEA Results
5. Conclusions
- The use of NSM-CFRP limited the failure modes of the beams to pure shear failure, in which no debonding or CFRP rapture was noticed during the test.
- The start, propagation, and inclination of the shear cracks depend on the NSM-CFRP scheme used. The shear cracks initiated after the first vertical NSM-CFRP strip if it was close to the support and changed its inclination between any two strips to reach the top face of the beam near the loading point.
- Experimental load-deflection curves indicated that beams with NSM-CFRP attached have higher ductility than their corresponding control beams as they recorded higher deflection values.
- In general, the experimental shear capacity increased with the increase of the compressive strength used for all beams strengthened with the same NSM-CFRP configuration.
- The experimental shear capacity of all beams strengthened with NSM-CFRP was higher than their corresponding control beams, in which the enhancement in shear capacity was in a range of 4–66%. The highest enhancement was recorded for beams with the unaligned two NSM-CFRP strips pattern, followed by the unaligned one NSM-CFRP strip pattern and then the aligned strips.
- The ACI 440.2R-17 was found to be conservative and predicted lower capacities than the experimental ones. However, the effect of the alignment between the NSM-CFRP strips and internal shear stirrups, as well as the number of unaligned NSM-CFRP strips, were not taken into consideration; thus, the theoretical values and enhancement percentages did not match the experimental results. As a result, the code equations for the shear design of NSM-CFRP should be adjusted to consider these factors to obtain more accurate capacities.
- The FEA showed acceptable results with respect to the crack patterns and maximum load capacities.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Density | Glass Transition Temperature | Fiber Volume Content | E-Modulus (Mean Value) | Tensile Strength (Mean Value) | Strain at Break (Minimum Value) |
---|---|---|---|---|---|
1.60 g/cm3 | >100 °C | >68% | 165,000 N/mm2 | 3100 N/mm2 | >1.70% |
Density | Thermal Expansion Coefficient | E-Modulus (Mean Value) | Tensile Strength (Mean Value) | Bond Strength | Elongation at Break |
---|---|---|---|---|---|
1.30 kg/L ± 0.1 kg/L (part A + B mixed) | 4.5 × 10−5 per °C (−10 °C to +40 °C) | 3800 N/mm2 (7 days at +23 °C) | 30 N/mm2 (7 days at +23 °C) | Concrete fracture (>4 N/mm2) on sandblasted substrate | 0.9% (7 days at +23 °C) |
4500 N/mm2 (7 days at +23 °C) |
Sample | Experimental Load (kN) | Percent Increase (%) | |
---|---|---|---|
Low Strength Concrete | BL | 105.0 | - |
BL-A | 121.3 | 16% | |
BL-U1 | 113.4 | 8% | |
BL-U2 | 158.9 | 51% | |
Medium Strength Concrete | BM | 141.0 | - |
BM-A | 147.0 | 4% | |
BM-U1 | 149.4 | 6% | |
BM-U2 | 233.8 | 66% | |
High Strength Concrete | BH | 168.4 | - |
BH-A | 202.8 | 20% | |
BH-U1 | 234.5 | 39% | |
BH-U2 | 228.7 | 36% |
Sample | Experimental Shear Load (kN) | Theoretical Load (kN) | Percent Increase (%) | |
---|---|---|---|---|
Low Strength Concrete | BL | 52.5 | 40.3 | 23.2 |
BL-A | 60.6 | 42.5 | 29.9 | |
BL-U1 | 56.7 | 42.5 | 25.0 | |
BL-U2 | 79.5 | 43.3 | 45.5 | |
Medium Strength Concrete | BM | 70.5 | 52.6 | 25.5 |
BM-A | 73.5 | 56.1 | 23.7 | |
BM-U1 | 74.7 | 56.1 | 24.9 | |
BM-U2 | 116.9 | 57.3 | 50.9 | |
High Strength Concrete | BH | 84.2 | 58.5 | 30.5 |
BH-A | 101.4 | 62.8 | 38.0 | |
BH-U1 | 117.2 | 62.8 | 46.4 | |
BH-U2 | 114.3 | 64.4 | 43.7 |
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Abdel-Jaber, M.; Abdel-Jaber, M.; Katkhuda, H.; Shatarat, N.; El-Nimri, R. Influence of Compressive Strength of Concrete on Shear Strengthening of Reinforced Concrete Beams with Near Surface Mounted Carbon Fiber-Reinforced Polymer. Buildings 2021, 11, 563. https://doi.org/10.3390/buildings11110563
Abdel-Jaber M, Abdel-Jaber M, Katkhuda H, Shatarat N, El-Nimri R. Influence of Compressive Strength of Concrete on Shear Strengthening of Reinforced Concrete Beams with Near Surface Mounted Carbon Fiber-Reinforced Polymer. Buildings. 2021; 11(11):563. https://doi.org/10.3390/buildings11110563
Chicago/Turabian StyleAbdel-Jaber, Ma’en, Mu’tasim Abdel-Jaber, Hasan Katkhuda, Nasim Shatarat, and Rola El-Nimri. 2021. "Influence of Compressive Strength of Concrete on Shear Strengthening of Reinforced Concrete Beams with Near Surface Mounted Carbon Fiber-Reinforced Polymer" Buildings 11, no. 11: 563. https://doi.org/10.3390/buildings11110563