1 Introduction
2 Experimental Program
2.1 Test Specimens and Parameters
No | Damage level | FRP strengthening | FRP orientation | F′c (N/mm2) | Opening size mm |
---|---|---|---|---|---|
B1 |
–
|
–
|
–
| 39.3 |
–
|
B2 |
–
|
–
|
–
| 39.3 | 0.5d |
B3 |
–
| U wrap | Vertical | 39.3 | 0.5d |
B4 | 50% of B2 | U wrap | Vertical | 39.3 | 0.5d |
B5 | 50% of B2 | U wrap | Diagonal | 39.3 | 0.5d |
B6 | 70% of B2 | U wrap | Diagonal | 39.3 | 0.5d |
B7 | 70% of B2 | U wrap | Diagonal | 39.3 | 0.5d |
2.2 Materials’ Properties
Material | Tensile strength (MPa) | Bond strength (MPa) | Ultimate strain (%) | Elastic modulus (GPa) | Mixing ratio | Curing time (h) |
---|---|---|---|---|---|---|
Putty (TLS-502) | ≥30 | ≥Max (2.5, ftk) | – | – | 3:1 | 24 |
Primer (TLS-501) | – | ≥Max (2.5, ftk) | – | – | 4:1 | 24 |
Epoxy (TLS-503) | ≥40 | ≥Max (2.5, ftk) | ≥1.5 | ≥2500 | 4:1 | 72 |
Material | Type | Areal density (g/m2) | Ultimate tensile strength (MPa) | Modulus (GPa) | Thickness (mm) |
---|---|---|---|---|---|
AFRP | C1-AK-40 | 280 | 2100 | 120 | 0.193 |
2.3 Specimen Preparations and Test Setup
2.4 Instrumentation of LVDTs and Strain Gauges
3 Experimental Results and Discussions
3.1 Failure Mode and Cracks Pattern
Specimen | First shear crack (kN) | First flexural crack (kN) | Failure load (kN) | Failure mode |
---|---|---|---|---|
B1 | 69 | 100 | 251 | Shear failure |
B2 | 40 | 55 | 124 | Shear failure |
B3 | – | 61 | 178 | FRP debonding |
B4 | 40 | 65 | 160 | FRP peeling and shear failure |
B5 | 38 | 58 | 208.9 | Concrete crushing and FRP peeling |
B6 | 39 | 67 | 185.2 | Concrete crushing and FRP peeling |
B7 | 39 | 72 | 204 | Concrete crushing and FRP peeling |
Beam | At 80 kN | At 125 kN | At 150 kN | At failure |
---|---|---|---|---|
B1 | 0.15 | 0.33 | 0.39 | 1.45 |
B2 | 1.01 | 3.31 | – | 3.31 |
B3 | 0.84 | 2.46 | 3.38 | 4.65 |
B4 | 0.65 | 1.51 | 2.068 | 2.96 |
B5 | 0.85 | 1.32 | 1.94 | 3.45 |
B6 | 0.91 | 1.45 | 2.03 | 3.00 |
B7 | 0.20 | 0.56 | 0.95 | 1.87 |
3.2 Cracking Behaviors
3.3 Deflection Behavior
3.4 Strain Distribution
3.4.1 Reinforcement Strain
3.4.2 Concrete Strain
3.4.3 FRP Strain
4 Performance of the Current Analytical Equations Used in this Study
4.1 FRP Contribution
Beam |
V
c
(kN) |
V
s
(kN) |
V
f
(kN) |
V
n
(kN) |
P
theo. (kN) |
P
exp. (kN) |
\( \frac{{{{P}}_{{{\text{exp.}}}} }}{{{{P}}_{{{\text{theo}}.}} }} \)
|
---|---|---|---|---|---|---|---|
B1 | 33.71 | 73.27 | – | 107 | 214 | 251 | 1.17 |
B2 | 16.9 | 36.638 | – | 53.8 | 108 | 125 | 1.15 |
B3 | 16.90 | 36.638 | 55.54 | 109 | 218 | 178 | 0.82 |
B4 | 16.90 | 36.638 | 55.54 | 109 | 218 | 160 | 0.74 |
B5 | 16.90 | 36.638 | 75.87 | 129.4 | 258.8 | 209 | 0.82 |
B6 | 16.90 | 36.638 | 75.87 | 129.4 | 258.8 | 185 | 0.71 |
B7 | 16.90 | 36.638 | 75.87 | 129.4 | 258.8 | 204 | 0.80 |