Effect of Shear Resistance on Flexural Debonding Load-Carrying Capacity of RC Beams Strengthened with Externally Bonded FRP Composites
Abstract
:1. Introduction
2. Existing Experimental Findings and Conclusions in the Literature
3. Experimental Programs
Series | Beam | Dimensions of Beam | Rebar | FRP | Stirrup | |||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
a | w | h | b | c | l | lf | n × dia. * | n × tf | bf | dia.-s * | ||
A1 | A10, A13, A16, A18 | 750 | 500 | 250 | 120 | 20 | 2000 | 1800 | 2 ϕ 12 | 1 × 0.111 | 120 | ϕ 8–100 |
B1 | B10, B13, B16, B18 | 750 | 500 | 250 | 120 | 20 | 2000 | 1800 | 2 ϕ 16 | 1 × 0.111 | 120 | ϕ 8–75 |
A2 | A20, A23, A26, A28 | 750 | 500 | 250 | 120 | 20 | 2000 | 1800 | 2 ϕ 12 | 2 × 0.111 | 120 | ϕ 8–100 |
B2 | B20, B23, B26, B28 | 750 | 500 | 250 | 120 | 20 | 2000 | 1800 | 2 ϕ 16 | 2 × 0.111 | 120 | ϕ 8–75 |
D * | D1 | 600 | 600 | 200 | 100 | 20 | 2000 | 1620 | 2 ϕ 12 | 1 × 0.111 | 80 | ϕ 6–90 |
D2 | 600 | 600 | 200 | 100 | 20 | 2000 | 1620 | 2 ϕ 12 | 2 × 0.111 | 80 | ϕ 6–90 | |
D3 | 600 | 600 | 200 | 100 | 20 | 2000 | 1620 | 2 ϕ 12 | 1 × 0.111 | 30 + 30 | ϕ 6–90 | |
D4 | 600 | 600 | 200 | 100 | 20 | 2000 | 1620 | 2 ϕ 12 | 1 × 0.111 | 80 | ϕ 6–90 | |
C1 | C10 | 1250 | – | 400 | 300 | 40 | 3200 | 1100 | 4 ϕ 16 | 1 × 0.111 | 300 | ϕ 8–100 |
C13 | 1250 | – | 400 | 300 | 40 | 3200 | 1100 | 4 ϕ 16 | 1 × 0.111 | 300 | ϕ 8–100 | |
C16 | 1250 | – | 400 | 300 | 40 | 3200 | 1100 | 4 ϕ 16 | 1 × 0.111 | 300 | ϕ 8–100 | |
C2 | C20 | 1250 | – | 400 | 300 | 40 | 3200 | 1100 | 4 ϕ 16 | 2 × 0.111 | 300 | ϕ 8–100 |
C23 | 1250 | – | 400 | 300 | 40 | 3200 | 1100 | 4 ϕ 16 | 2 × 0.111 | 300 | ϕ 8–100 | |
C26 | 1250 | – | 400 | 300 | 40 | 3200 | 1100 | 4 ϕ 16 | 2 × 0.111 | 300 | ϕ 8–100 |
Series | Concrete | Rebar | Stirrup | FRP | ||||||
---|---|---|---|---|---|---|---|---|---|---|
fc * | ft | Es | fy | fu | Es | fyv | fu | Ef | fu | |
A1, A2 | 13.4 | 1.54 | 200,000 | 381 | 452 | 207,000 | 276 | 375 | 235,000 | 3,350 |
B1, B2 | 16.7 | 1.78 | 200,000 | 381 | 452 | 207,000 | 276 | 375 | 235,000 | 3,350 |
C1, C2 | 35.5 | 2.74 | 200,000 | 381 | 452 | 207,000 | 276 | 375 | 235,000 | 4,150 |
D1, D2, D3 | 23.4 | 2.20 | 200,000 | 378 | 447 | 205,000 | 235 | 362 | 243,000 | 4,390 |
D4 | 20.1 | 2.01 | 200,000 | 378 | 447 | 205,000 | 235 | 362 | 243,000 | 4,390 |
4. Results and Discussion
4.1. Test Results
Series | Beam | Tested Results | Analyzed Results | Vn/Vd | Vn/Vd | Vn/VMn | Vn/VMn | Md/Mn | Md/Mn | ||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
* Md | Vd | Mn | Vn | VMn | µ | CoV | µ | CoV | µ | CoV | |||||
A2 | A20 | 24.9 | 33.2 | 23.5 | 81.3 | 31.4 | 2.45 | 2.43 | 3.1% | 2.59 | 2.70 | 3.2% | 1.06 | 1.11 | 3.1% |
A23 | 26.1 | 34.8 | 22.9 | 81.3 | 30.5 | 2.34 | 2.66 | 1.14 | |||||||
A26 | 25.5 | 34.1 | 22.3 | 81.3 | 29.7 | 2.39 | 2.74 | 1.15 | |||||||
A28 | 24.0 | 32.0 | 21.6 | 81.3 | 28.8 | 2.54 | 2.82 | 1.11 | |||||||
B2 | B20 | 31.4 | 41.8 | 33.0 | 105.1 | 44.0 | 2.51 | 2.31 | 6.0% | 2.39 | 2.45 | 1.8% | 0.95 | 1.06 | 6.6% |
B23 | 36.2 | 48.3 | 32.5 | 105.1 | 43.3 | 2.18 | 2.43 | 1.11 | |||||||
B26 | 36.0 | 48.1 | 32.0 | 105.1 | 42.6 | 2.19 | 2.47 | 1.13 | |||||||
B28 | 33.6 | 44.8 | 31.5 | 105.1 | 42.0 | 2.35 | 2.51 | 1.07 | |||||||
C1 | C10 | 136.5 | 109.2 | 155.0 | 223.4 | 124.0 | 2.05 | 2.19 | 4.6% | 1.80 | 1.82 | 0.6% | 0.88 | 0.83 | 4.1% |
C13 | 125.3 | 100.2 | 153.7 | 223.4 | 123.0 | 2.23 | 1.82 | 0.81 | |||||||
C16 | 122.5 | 98.0 | 152.6 | 223.4 | 122.1 | 2.28 | 1.83 | 0.80 | |||||||
C2 | C20 | 136.4 | 109.1 | 197.2 | 223.4 | 157.8 | 2.05 | 1.96 | 3.2% | 1.42 | 1.43 | 1.0% | 0.69 | 0.73 | 4.0% |
C23 | 136.4 | 116.5 | 194.7 | 223.4 | 155.8 | 1.92 | 1.43 | 0.75 | |||||||
C26 | 145.6 | 116.8 | 192.6 | 223.4 | 154.0 | 1.91 | 1.45 | 0.76 | |||||||
D | D1 | 15.8 | 26.3 | 16.0 | 61.2 | 26.6 | 2.33 | 2.28 | 1.7% | 2.30 | 2.28 | 6.0% | 0.99 | 1.00 | 6.5% |
D2 | 16.1 | 26.9 | 17.9 | 61.2 | 29.9 | 2.27 | 2.05 | 0.90 | |||||||
D3 | 16.1 | 26.9 | 15.4 | 61.2 | 25.6 | 2.28 | 2.39 | 1.05 | |||||||
D4 | 16.1 | 26.9 | 16.0 | 59.8 | 26.6 | 2.27 | 2.37 | 1.07 |
4.2. Influence of Shear Resistance of RC Beam on Flexural Debonding Load-Carrying Capacity
5. Conclusions
- The shear resistance of RC beam has a great effect on flexural debonding load-carrying capacity of FRP-strengthened RC beam. The influence of shear resistance on flexural debonding load-carrying capacity must be fully considered in flexural strengthening design of RC beams.
- Md/Mn and Vn/Vd have a good linear relationship. The flexural debonding load-carrying capacity is significantly increased with the increase of Vn/Vd. The goodness of the linear fit of Md/Mn and Vn/VMn is better than that of Md/Mn and Vn/Vd, and their variation tendency is the same. Therefore, the relationship between Md/Mn and Vn/VMn can also be used in evaluating the influence of shear resistance on flexural debonding load-carrying capacity, and also provides support for flexural strengthening design. It is suggested that Vn/VMn should not be less than 2.3 in order to prevent debonding failure of FRP reinforcements as FRP-strengthened RC beam reaches its nominal flexural strength.
- The existing debonding models were developed based on the single-shear test results. However, the experimental results proved that the shear resistance of RC beam plays the key role in FRP debonding failure. Consequently, the influence of shear resistance of RC beam on FRP debonding failure must be fully considered in developing the debonding criteria and model.
- Presently, only a few of experimental studies have been carried out against investigating the influence of shear resistance on flexural debonding load-carrying capacity of FRP-strengthened RC beams. This vital issue, which remains under investigated, must be given the attention it deserves through further experimental and analytical studies.
Acknowledgments
Author Contributions
Conflicts of Interest
References
- Teng, J.G.; Smith, S.T.; Yao, J.; Chen, J.F. Intermediate crack-induced debonding in RC beams and slabs. Constr. Build. Mater. 2003, 17, 447–462. [Google Scholar] [CrossRef]
- Hosseini, A.; Mostofinejad, D. Effective bond length of FRP-to-concrete adhesively-bonded joints: Experimental evaluation of existing models. Int. J. Adhes. Adhes. 2014, 48, 150–158. [Google Scholar] [CrossRef]
- Chen, J.; Teng, J. Anchorage strength models for FRP and steel plates bonded to concrete. J. Struct. Eng. 2001, 127, 784–791. [Google Scholar] [CrossRef]
- Khalifa, A.; Gold, W.; Nanni, A.; Abdel-Aziz, M.I. Contribution of externally bonded FRP to shear capacity of RC flexural members. J. Compos. Constr. 1998, 2, 195–202. [Google Scholar] [CrossRef]
- Dai, J.; Ueda, T.; Sato, Y. Development of the nonlinear bond stress–slip model of fiber reinforced plastics sheet–concrete interfaces with a simple method. J. Compos. Constr. 2005, 9, 52–62. [Google Scholar] [CrossRef]
- Seracino, R.; Raizal Saifulnaz, M.; Oehlers, D. Generic debonding resistance of EB and NSM plate-to-concrete joints. J. Compos. Constr. 2007, 11, 62–70. [Google Scholar] [CrossRef]
- Yuan, H.; Wu, Z.S. Interfacial fracture theory in structures strengthened with composite of continuous fiber. In Proceedings of the Symposium of China and Japan science and technology of the 21st century, Tokyo, Japan, 13–15 September 1999; pp. 142–155.
- Yuan, H.; Wu, Z.S.; Yoshizawa, H. Theoretical solution on interfacial stress transfer of externally bonded steel/composite laminates. J. Struct. Eng. Earthq. Eng. 2001, 18, 27–39. [Google Scholar]
- Wu, Y.-F.; Xu, X.-S.; Sun, J.-B.; Jiang, C. Analytical solution for the bond strength of externally bonded reinforcement. Compos. Struct. 2012, 94, 3232–3239. [Google Scholar] [CrossRef]
- Yuan, H.; Lu, X.; Hui, D.; Feo, L. Studies on FRP-concrete interface with hardening and softening bond-slip law. Compos. Struct. 2012, 94, 3781–3792. [Google Scholar] [CrossRef]
- Kim, Y.; Harries, K. Statistical characterization of reinforced concrete beams strengthened with FRP sheets. J. Compos. Constr. 2013, 17, 357–370. [Google Scholar] [CrossRef]
- Kalfat, R.; Al-Mahaidi, R.; Smith, S. Anchorage devices used to improve the performance of reinforced concrete beams retrofitted with FRP composites: State-of-the-art review. J. Compos. Constr. 2013, 17, 14–33. [Google Scholar] [CrossRef]
- Pesic, N.; Pilakoutas, K. Concrete beams with externally bonded flexural FRP-reinforcement: Analytical investigation of debonding failure. Compos. B Eng. 2003, 34, 327–338. [Google Scholar] [CrossRef]
- Bilotta, A.; Ludovico, M.D.; Nigro, E. FRP-to-concrete interface debonding: Experimental calibration of a capacity model. Compos. B Eng. 2011, 42, 1539–1553. [Google Scholar] [CrossRef]
- Radfar, S.; Foret, G.; Saeedi, N.; Sab, K. Simulation of concrete cover separation failure in FRP plated RC beams. Constr. Build. Mater. 2012, 37, 791–800. [Google Scholar] [CrossRef]
- Chen, J.F.; Yuan, H.; Teng, J.G. Debonding failure along a softening FRP-to-concrete interface between two adjacent cracks in concrete members. Eng. Struct. 2007, 29, 259–270. [Google Scholar] [CrossRef]
- Finckh, W.; Zilch, K. Strengthening and rehabilitation of reinforced concrete slabs with carbon-fiber reinforced polymers using a refined bond model. Comput. Aided Civ. Infrastruct. Eng. 2012, 27, 333–346. [Google Scholar] [CrossRef]
- Lu, X.Z.; Teng, J.G.; Ye, L.P.; Jiang, J.J. Intermediate crack debonding in FRP-strengthened RC beams: FE analysis and strength model. J. Compos. Constr. 2007, 11, 161–174. [Google Scholar] [CrossRef]
- Oehlers, D.J.; Liu, I.; Seracino, R. A generic design approach for EB and NSM longitudinally plated RC beams. Constr. Build. Mater. 2007, 21, 697–708. [Google Scholar] [CrossRef]
- Oller Ibars, E.; Cobo del Arco, D.; Marí Bernat, A. Design proposal to avoid peeling failure in FRP-strengthened reinforced concrete beams. J. Compos. Constr. 2009, 13, 384–393. [Google Scholar] [CrossRef]
- Said, H.; Wu, Z. Evaluating and proposing models of predicting IC debonding failure. J. Compos. Constr. 2008, 12, 284–299. [Google Scholar] [CrossRef]
- Wu, Z.S.; Niu, H.D. Prediction of crack-induced debonding failure in R/C structures flexurally strengthened with externally bonded FRP composites. JSCE J. Mater. Concr. Struct. Pavements 2007, 63, 620–639. [Google Scholar] [CrossRef]
- Bilotta, A.; Faella, C.; Martinelli, E.; Nigro, E. Design by testing procedure for intermediate debonding in EBR FRP strengthened RC beams. Eng. Struct. 2013, 46, 147–154. [Google Scholar] [CrossRef]
- Externally Bonded FRP Reinforcement for RC Structures; fib Bulletin No. 14; Technical Report on the Design and Use of Externally Bonded Fibre Reinforced Polymer Reinforcement (FRP EBR) for Reinforced Concrete Structures: Lausanne, Switzerland, 2001; pp. 51–58.
- Maruyama, K. Recommendatios for Upgrading of Concrete Structures with Use of Continuous Fiber Sheets; Nagaoka University of Technology: Nagaoka, Japan, 2001; p. 88. [Google Scholar]
- Design Guidance on Strengthening Concrete Structures Using Fiber Composite Materials, 2nd ed.; Concrete Society Technical Report No.55; London, UK, 2004.
- Guidelines for Design, Execution and Control of Strengthening Interventions by Means of Fibre-Reinforced Composites—Materials, Reinforced Concrete and Prestressed Concrete Structures, Masonry Structures; CNR DT200; National Research Council, Advisory Committee on Technical Regulations for Constructions: Rome, Italy, 2004; p. 164.
- Lee, D.; Cheng, L. Bond of NSM systems in concrete strengthening—Examining design issues of strength, groove detailing and bond-dependent coefficient. Constr. Build. Mater. 2013, 47, 1512–1522. [Google Scholar] [CrossRef]
- Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures; ACI-440.2R-08; American Concrete Institute (ACI): Farmington Hills, MI, USA, 2008; p. 76.
- Hassan, T.; Rizkalla, S. Investigation of bond in concrete structures strengthened with near surface mounted carbon fiber reinforced polymer strips. J. Compos. Constr. 2003, 7, 248–257. [Google Scholar] [CrossRef]
- Oehlers, D.; Haskett, M.; Wu, C.; Seracino, R. Embedding NSM FRP plates for improved IC debonding resistance. J. Compos. Constr. 2008, 12, 635–642. [Google Scholar] [CrossRef]
- Mohamed Ali, M.S.; Oehlers, D.J.; Griffith, M.C.; Seracino, R. Interfacial stress transfer of near surface-mounted FRP-to-concrete joints. Eng. Struct. 2008, 30, 1861–1868. [Google Scholar]
- Hassan, T.K.; Rizkalla, S.H. Bond mechanism of near-surface-mounted fiberreinforced polymer bars for flexural strengthening of concrete structures. ACI Struct. J. 2004, 101, 830–839. [Google Scholar]
- Recommendations for Updating of Concrete Structures with Use of Continuous Fiber Sheets, Concrete Engineering Series 41; Japan Society of Civil Engineers: Tokyo, Japan, 2001; pp. 31–34.
- Toutanji, H.; Ueno, S.; Vuddandam, R. Prediction of the interfacial shear stress of externally bonded FRP to concrete substrate using critical stress state criterion. Compos. Struct. 2013, 95, 375–380. [Google Scholar] [CrossRef]
- Büyükoztürk, O.; Gunes, O.; Karaca, E. Characterization and modeling of debonding in RC beams strengthened with FRP composites. In Proceedings of the 15th ASCE Engineering Mechanics Conference, Columbia University, New York, NY, USA, 2–5 June 2002; pp. 1–8.
- Garden, H.N.; Quantrill, R.J.; Hollaway, L.C.; Thorne, A.M.; Parke, G.A.R. An experimental study of the anchorage length of carbon fiber composite plates used to strengthen reinforced concrete beams. Constr. Build. Mater. 1998, 12, 203–219. [Google Scholar] [CrossRef]
- Garden, H.N.; Hollaway, L.C. An experimental study of the influence of plate end anchorage of carbon fibre composite plates used to strengthen reinforced concrete beams. Compos. Struct. 1998, 42, 175–188. [Google Scholar] [CrossRef]
- Rabinovitch, O.; Frostig, Y. Experiments and analytical comparison of RC beams strengthened with CFRP composites. Compos. B Eng. 2003, 34, 663–677. [Google Scholar] [CrossRef]
- Pham, H.; Al-Mahaidi, R. Experimental investigation into flexural retrofitting of reinforced concrete bridge beams using FRP composites. Compos. Struct. 2004, 66, 617–625. [Google Scholar] [CrossRef]
- Pham, H.; Al-Mahaidi, R. Prediction models for debonding failure loads of carbon fiber reinforced polymer retrofitted concrete beams. J. Compos. Constr. 2006, 10, 48–59. [Google Scholar] [CrossRef]
- Zhang, A.H.; Jin, W.L.; Li, G.B. Behavior of preloaded RC beams strengthened with CFRP laminates. J. Zhejiang Univ. Sci. A 2006, 7, 436–444. [Google Scholar]
- Yang, Y.X.; Yue, Q.R.; Ye, L.P.; Hu, Y.C. Debonding failure of reinforced concrete beams strengthened with carbon fiber sheets. Eng. Mech. 2004, 21, 150–156. [Google Scholar]
- Yao, J.; Teng, J.G.; Chen, J.F. Experimental study on FRP-to-concrete bonded joints. Compos. B Eng. 2005, 36, 99–113. [Google Scholar] [CrossRef]
- Pan, J.; Leung, C.K.Y. Debonding along the FRP-concrete interface under combined pulling/peeling effects. Eng. Fract. Mech. 2007, 74, 132–150. [Google Scholar] [CrossRef]
- Pan, J. Crack-Induced Debonding Failure in Fiber Reinforced Plastics (FRP) Strengthened Concrete Beams: Experimental and Theoretical Analysis. Ph.D. Thesis, Hongkong University of Science and Technology, Hongkong, China, 17 September 2005. [Google Scholar]
- Teng, J.G.; Chen, J.F.; Smith, S.T.; Lam, L. FRP-Strengthened RC Structures; John Wiley and Sons: Hoboken, NJ, USA, 2002; p. 246. [Google Scholar]
- Li, G. Study on Flexural Behavior and Deboding Failure of CFRP-Strengthened RC Beams. Ph.D. Thesis, Zhejiang University, Hangzhou, China, 23 May 2006. [Google Scholar]
- Li, Y.; Liu, Z.; Hu, C. Research on shear stress of debonding plate-end of RC beam strengthened with CFRP. J. Henan Polytech. Uni. Nat. Sci. 2007, 26. [Google Scholar] [CrossRef]
- Ministry of Housing and Urban-Rural Development PRC, Code for Design of Concrete Structures; China Achitecture & Building Press: Beijing, China, 2010; p. 425.
© 2014 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/3.0/).
Share and Cite
Li, G.; Zhang, A.; Jin, W. Effect of Shear Resistance on Flexural Debonding Load-Carrying Capacity of RC Beams Strengthened with Externally Bonded FRP Composites. Polymers 2014, 6, 1366-1380. https://doi.org/10.3390/polym6051366
Li G, Zhang A, Jin W. Effect of Shear Resistance on Flexural Debonding Load-Carrying Capacity of RC Beams Strengthened with Externally Bonded FRP Composites. Polymers. 2014; 6(5):1366-1380. https://doi.org/10.3390/polym6051366
Chicago/Turabian StyleLi, Guibing, Aihui Zhang, and Weiliang Jin. 2014. "Effect of Shear Resistance on Flexural Debonding Load-Carrying Capacity of RC Beams Strengthened with Externally Bonded FRP Composites" Polymers 6, no. 5: 1366-1380. https://doi.org/10.3390/polym6051366