Fiber Reinforced Polymer Strengthening of Structures by Near-Surface Mounting Method
Abstract
:1. Introduction
2. Flexural Applications of NSM-FRP for Concrete Members
3. Shear Applications of NSM-FRP for Concrete Members
4. Prestressed NSM-FRP Applications for Concrete Members
5. NSM-FRP to Concrete Bond Performance
5.1. Surface Treatment of FRP Bars or Rods
5.2. Adhesive Types
5.3. NSM Groove and Bar Dimensions
5.4. Bonded Length
6. NSM-FRP Applications for Masonry Walls
6.1. NSM-FRP Masonry Bond Studies
6.2. In Plane Shear
6.3. Out of Plane Flexure
7. NSM-FRP Applications under Temperature
8. Emerging and Innovative Methods to Improve the Performance of NSM-FRP Strengthening
9. Conclusions
Acknowledgments
Author Contributions
Conflicts of Interest
Abbreviations
NSM | near surface mounting |
EBR | externally bonding reinforcement |
FRP | fiber reinforced polymers |
CFRP | carbon fiber reinforced polymers |
RC | reinforced concrete |
ACI | American Concrete Institute |
FIB | Fédération Internationale du Béton |
CSA | Canadian Standards Association |
HCP | hybrid composite plate |
SHCC | strain hardening cementitious composite |
URM | unreinforced masonry |
ASTM | American Society of the International Association for Testing and Materials |
ISO | International Organization for Standardization |
IC | intermediate crack |
BFRP | basalt fiber reinforced polymers |
Tg | glass transition temperature |
Td | decomposition temperature |
CS | calcium silicate |
VP | vermiculite/perlite |
MG | cement and epoxy binder mixed grout |
DMA | dynamic mechanical analysis |
TGA | thermogravimetric analysis |
ETS | embedded through section |
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Reference | [7] | [8] | [9] | [10] | [11] |
Test type | Flexure | ||||
Specimen | Simply supported RC T-beams | Cantilevered RC bridge slab and RC beam | Simply supported RC beams | Simply supported RC beams | Simply supported RC beams |
Cross-section dimensions, l × w × d (mm) | Span = 4,572, flange = 381 × 102, web = 152 × 305 | Bridge spans = 61.1, 64.1, and 80.0, beam = 900 × 170 × 200 | 1,000 × 120 × 170 | 3010 × 200 × 300 | 2800 × 150 × 280 |
f'c (MPa) | 36.17 | 31.4 | 37.6–49.5 | 35 | 36.5–67.2 |
Test method | 4 point bending | Cantilever, and three-point bending | Four-point bending | Four-point bending | Four-point bending |
FRP material type and configuration | GFRP (deformed), and CFRP (sand blasted) rods | CFRP strips | CFRP sheet and laminate | CFRP, and GFRP rods | CFRP rods |
FRP diameter df or FRP sheet width wf (mm) a | 9.5 and 12.7 | - | 0.111–0.167 | 9.5, 12.7, 11.3 and 15.9 | 6 and 12 |
FRP cross-section hf × tf (mm) a | - | 16 × 2 | 10 × 1.4 | - | - |
Groove dimensions hg × tg (mm) a | 16 × 16, 19 × 19, and 25.4 × 25.4 | 20 × 4 | N/Ab | 1.5–2 times df a | 12 × 12, and 24 × 24 |
Test variables | Bonded length, FRP rod diameter, material, and groove | Variable loading conditions, and long term durabilty test | Distance between FRP rods, and FRP reinforcement ratio | Steel reinforcement ratio, FRP rod diameters and bonded lengths, material | Concrete strength, and epoxy |
Observed failure mode | Concrete crushing, FRP debonding | N/A b | Delamination of concrete cover, FRP debonding and rupture | Steel yielding, and concrete cover splitting | Concrete cover peel-off, FRP pull-out and concrete crushing |
Increase in ultimate load | 25.7%–44.3% | 41% | 83% (averaged) | up to 104% | 59.2–73.2 kN |
Reference | [13] | [14] | [15] | [16] |
Test type | Shear | |||
Specimen | Simply-supported concrete and RC beams | Simply-supported RC beams | Simply-supported deep RC T-beams | Simply-supported RC beams |
Cross-section dimensions, l × w × d (mm) | 1500 × 150 × 300, and 900 × 150 × 150 | 2000 × 200 × 210 | Span = 4200, flange = 450 × 100, web = 180 × 500 | 1650 × 200 × 250 |
f'c (MPa) | 37.6–49.5 | 29.3 | 40.1 | 36.4 |
Test method | Four-point bending | Four-point bending | Three-point bending | Three-point bending |
FRP material type and configuration | CFRP strip | CFRP rods, and strips | CFRP rods | CFRP sheets wrapped around wooden rods |
FRP Diameter df (mm) a | - | 7.5 and 8 | - | - |
FRP Cross-Section hf × tf (mm) a | 10 × 1.4 | 16 × 2 | 10 × 1.4, and 20 × 1.4 | 0.11 |
Groove dimensions hg × tg (mm) a | 12 × 5 | 15 × 15, and 18 × 5 | N/A b | 15 × 15 |
Test variables | FRP spacing and inclination | FRP forms, epoxy, spacing and inclination of FRP | FRP dimensions, spacings and orientations | FRP end anchorage, spacings and orientations |
Observed failure mode | Shear cracking | Shear cracking, and FRP debonding | Shear cracking, and FRP rupture | Shear-flexural cracking |
Increase in ultimate load | 83% (averaged) | 22%–44% | 66%–85% | 25%–48% |
Reference | [17] | [18] | [19] | [20] |
Test type | Prestressing | |||
Specimen | Simply-supported RC beam | Simply-supported RC beam | Simply-supported RC beam | Simply supported RC slab |
Cross-section dimensions, l × w × d (mm) | 3300 × 300 × 350 | 3200 × 200 × 300 | 5150 × 200 × 400 | 2600 × 600 × 120 |
f'c (MPa) | 31 | 27 | 40 | 46.7 |
Test method | Three-point bending | Four-point bending | Four-point bending | Four-point bending |
FRP saterial sype and sonfiguration | NSM CFRP laminate strips (sand coated) | NSM CFRP plates | NSM CFRP strips | NSM CFRP laminates |
FRP cross-Section hf × tf (mm) a | 25 × 2 | 25 × 1.4 | 16 × 2 | 20 × 1.4 |
Prestressing strain levels (%) | 5, 20 and 30 | 0–50 | 0, 20, 40, 60 | 20 and 40 |
Test variables | Prestressing levels under service-load state | Prestressing levels and transverse grooves | Fatigue, in-service loading conditions | Prestressing levels, under service and ultimate loads |
Observed failure mode | FRP rupture | FRP debonding, and concrete cover seperation | FRP debonding and FRP slippage at end anchorages | FRP rupture |
Increase in ultimate load | 11.5%–15% | 42%–96% | 44.1–88.2 kN | 136%–152% |
Reference | [21] | [22] | [23] | [24] |
Test type | Prestressing | |||
Specimen | Simply supported, RC slab | Simply supported, RC slab | Simply supported, stone slab | Simply supported, RC slab |
Cross-section dimensions, l × w × d (mm) | 2600 × 600 × 120 | 2400 × 150 × 300 | 3400 × 450 × 100 | 1800 × 150 × 300 |
f'c (MPa) | 15 | 32.2 | 142.4 | 27.7 |
Test method | 4-Point bending | 4-Point bending | 4-Point bending | 4-Point bending |
FRP material type and configuration | NSM CFRP laminates | NSM CFRP laminates | NSM CFRP bars (rough surfaces) | NSM CFRP bars (spirally wound) |
FRP diameter df (mm) a | - | - | 7 | 7.9 |
FRP cross-section hf × tf (mm) a | 20 × 1.4 | 20 × 1.4 | - | - |
Groove dimensions hg × tg (mm) a | - | 24 × 6 | 27 × 14 | 20 × 20 |
Prestressing strain levels (%) | 20 and 40 | 0, 20, 30, and 40 | 0, 15 and 30 | 40 |
Test variables | Low concrete compressive strength, serviceability limit states | Prestressing levels, low steel reinforcement ratio of 0.39% | Prestressing levels, no steel reinforcement | Number of FRP bars, end treatments, and prestressing levels |
Observed failure mode | FRP rupture | Concrete crushing and FRP rupture | FRP rupture, and excessive deflection | FRP bar slippage, and concrete crushing |
Increase in ultimate load | 125% and 134% | 32%, 47%, 55% and 63% | 30%–60% (Cracking load) | 71% |
Reference | [33] | [34] | [35] | [36] | [37] | |
Test type | In plane shear | |||||
Specimen | URM walls | URM walls | URM walls | URM walls | URM walls | |
Wall dimensions, h × l (mm) | 1200 × 1200 | 1200 × 1200 | 1170 × 1170, and 1170 × 1075 | 1200 × 1200 | 1204 × 1190, and 1032 × 1910 | |
Masonry brick compressive strength f'b (MPa) | 8.8–19.4 | N/A b | 11.2–21.2 | 28.6 | 21.3 | |
Test method | Diagonal tension | Diagonal tension | Diagonal compression | Cyclic shear and vertical compression | Cyclic shear | |
FRP material type and configuration | NSM CFRP strips | NSM CFRP strips | Anchored EB CFRP plates, and GFRP fabrics and strips | NSM CFRP strips | NSM CFRP strips | NSM CFRP strips |
FRP cross-section hf × tf (mm) or w (mm) a | 12 × 1.2, 30 × 1.2 | 15 × 2.8 | Width ranging from 50–150 | 15 × 1.2 | 10 × 1.4 | 15 × 2.8 |
Groove dimensions hg × tg (mm) a | 20 × 8, 35 × 8 | 20 × 6 | N/A b | N/A b | 15 × 8 | |
Orientation of FRP | Vertical and diagonal | Vertical and horizontal | Vertical, horizontal and diagonal | Vertical and horizontal | Vertical and horizontal | |
Test variables | FRP orientation, number of strips, and position | FRP orientation, number of strips, and position | FRP form, orientation, number of strips, and position | FRP orientation, pre-compression levels, number of strips, and position | FRP orientation, and boundary conditions | |
Observed failure mode | Diagonal cracking, sliding and FRP debonding | Diagonal cracking, sliding and FRP debonding | Diagonal cracking, sliding and FRP debonding | Diagonal cracking | Diagonal cracking, and sliding | |
Increase in wall strength | 1.3–3.7 times | 1%–46% | 31%–325% | 9.30% | 1%–9% |
Reference | [38] | [39] | [40] | [41] |
Test type | Out of plane flexure | |||
Specimen | URM wall, and column | URM walls | URM walls | URM walls |
Wall dimensions, h × l (mm) | 2313 × 1070, and 1710 × 355 | 3000–4100 × 1150, and 2700–4000 × 1170 × 1250 | 3900 × 2800 | 1170 × 1250 |
Masonry brick compressive strength f'b (MPa) | 17 | 17.1–39.5 | 16.9–27.6 | 8.8–32 |
Test method | Three and four-point bending | Three and four-point bending | Monotonically increasing lateral pressure | Lateral pressure |
Material type and configuration | NSM CFRP strips | NSM CFRP strips | NSM CFRP cable | NSM CFRP strips, and NSM twisted steel bars |
FRP diameter df (mm) a | - | - | 5 | - |
FRP cross-section hf × tf (mm) a | 10 × 4.2, 10 × 3.6, 10 × 7.2, 7.5 × 4.8, and 5 × 4.8 | 15 × 1.2 | - | 15 × 1.2 |
Groove dimensions hg × tg (mm) a | N/A b | 20 × 8 | N/A b | N/A b |
Orientation of FRP | Vertical | Vertical | Vertical and horizontal | Vertical |
Test variables | FRP spacing, reinforcement ratio, and cyclic and pre-compression loadings | Wall dimensions, one-or two-sided FRP retrofit | Low FRP reinforcement ratios, pre-compression loads, various support conditions | In-situ and pre-compression loads |
Observed failure mode | IC debonding | Displacement Induced (DI) debonding | Diagonal cracking, compressive crushing of masonry, FRP slip, and shear rupture | FRP debonding, and FRP pull-out |
Increase in wall strength | up to 20 times | 3.05–6.21 times | 25%–291% | 440%–830% |
Reference | [43] | [44,45] | [4] | [46] | |
Test type | Temperature | ||||
specimen | N/A | Simply-supported RC beam | Simply-supported RC beam | Simply-supported RC beam | |
Cross-section dimensionsl × w × d (mm) | N/A | 3150 × 200 × 300 | 1524 × 254 × 102 | 4100 × 200 × 450 | |
Temperature range (°C) | 20–600 | ISO 834 | 21–200 | ISO 834 | |
Insulation type | N/Ab | Glass-fiber cement, CS c, two component system and ceramic | Ceramic | Rock-wool and CS c | |
Insulation length (mm) | N/A b | 2900 | FRP bonded length | 225–850 | |
Test method | Tension test | Service load and EN 1363-1 standard fire | Monotonic or service load, and transient high temperature | Four-point bending, and standard fire | |
FRP Material type and configuration | CFRP strips and rods | CFRP and GFRP rods | CFRP fabric and tape | Basalt FRP bars | |
FRP Tg (°C) | 80 | 82 | 59 and 122 | N/A b | |
FRP diameter df (mm) a | 6.4 | 9.5–16 | - | 10 | |
FRP cross-section hf × tf (mm) a | 13.5 × 4.5 | - | 235 × 0.381, 16 × 2 | - | |
Adhesive or resin type | High strength epoxy and expansive cement | Epoxy | Epoxy and cementitious material | Vinyl, heat resistance vinyl, and epoxy | |
Adhesive Tg (°C) | N/A b | 62–65 | 59 and 69 | 127, 174, and 210 | |
Groove dimensions hg × tg (mm) a | N/A b | N/A b | 21 × 5 | 20 × 20 | |
Test variables | High temperature, various epoxy and FRP forms | Various insulation systems | High temperature, various adhesive, and insulation lengths | High Tg resin, and insulation thickness | |
Observed failure mode (s) | Splitting or rupture of FRP fibers, resin decomposition | FRP debonding, and concrete crushing | FRP debonding | Flexural | |
Thermal performance | N/A b | 1–2 h | 4 h at 100 °C, and 70 min at 200 °C | 88–147 min | |
Reference | [47] | [48] | [49] | [50] | [51] |
Test type | Temperature | ||||
Specimen | Simply-supported RC beam | Simply-supported RC beam | Simply-supported RC T-beams | RC Concrete blocks | Simply-supported RC beam |
Cross-section dimensions l × w × d (mm) | 2100 × 100 × 120 | 1350 × 120 × 200 | Span = 3962, flange 432 × 127, web = 229 × 279 | 350 × 120 × 120 | 1450 × 150 × 150 |
Temperature range (°C) | ISO 834 | ISO 834 | ASTM E119 | 20–150 | N/A b |
Insulation type | CS c, and VP d mortar | CS c | U-shaped Tyfo®CFP e | - | N/A b |
Insulation length (mm) | Anchorage zones | Anchorage zones | 3180 | - | Anchorage zones |
Test method | Four-point bending, and standard fire | Four-point bending, and standard fire | Four-point bending, and standard fire | Double-lap shear test, and high temperature | DMA f, TGA g and thermal conductivity, and four-point bending test, and thermal load |
FRP material type and configuration | CFRP laminate | CFRP strips | CFRP strips | CFRP strips | CFRP bar |
FRP Tg (°C) | N/A b | 83 | N/A b | 83 | 220 |
FRP diameter df (mm) a | - | - | - | - | N/A b |
FRP cross-section hf × tf (mm) a | 50 × 1.2 | 10 × 1.2 | 13.5 × 4.5 | 10 × 1.2 | - |
Adhesive or resin type | Epoxy | Epoxy, and mixed grout | Epoxy | Epoxy, and mixed grout | Cementitious grout |
Adhesive Tg (°C) | 55 | 47 and 44 | N/A b | 47 and 44 | N/A b |
Groove dimensions hg × tg (mm) a | N/A b | N/A b | N/A b | 15 × 5 | N/A b |
Test variables | Fire protection schemes, and Tg of epoxy | Adhesive type, and fire protection schemes | Fire protection zones, and schemes | Adhesive type, bonded length | Material testing procedures, and fire protection schemes |
Observed failure mode (s) | Structural failure | FRP debonding | FRP decomposition | Shear failure, and adhesive failure | FRP debonding |
Thermal performance | 60–90 min | 114 min | 3 h | N/A | 90 min |
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Parvin, A.; Syed Shah, T. Fiber Reinforced Polymer Strengthening of Structures by Near-Surface Mounting Method. Polymers 2016, 8, 298. https://doi.org/10.3390/polym8080298
Parvin A, Syed Shah T. Fiber Reinforced Polymer Strengthening of Structures by Near-Surface Mounting Method. Polymers. 2016; 8(8):298. https://doi.org/10.3390/polym8080298
Chicago/Turabian StyleParvin, Azadeh, and Taqiuddin Syed Shah. 2016. "Fiber Reinforced Polymer Strengthening of Structures by Near-Surface Mounting Method" Polymers 8, no. 8: 298. https://doi.org/10.3390/polym8080298