Flexural Strength of RC Beam Strengthened by Partially De-bonded Near Surface-Mounted FRP Strip

다국어 초록 (Multilingual Abstract)

This paper presents an experimental work to study the flexural strength of reinforced concrete (RC) beamsstrengthened by partially de-bonded near surface-mounted (NSM) fiber reinforced polymer (FRP) strip with various de-bondedlength. Especially, considering high anchorage capacity at end of a FRP strip, the effect of de-bonded region at a central part wasinvestigated. In order to check the improvement of strength or deformation capacity when the bonded surface area only increasedwithout changing the FRP area, single and triple lines of FRP were planned. In addition, the flexural strength of the RC memberstrengthened by a partially de-bonded NSM FRP strip was evaluated by using the existing researchers’ strength equation to predictthe flexural strength after retrofit. From the study, it was found that where de-bonded region exists in the central part of a flexuralmember, the deformation capacity of the member is expected to be improved, because FRP strain is not to be concentrated on thecenter but to be extended uniformly in the de-bonded region. Where NSM FRP strips are distributed in triple lines, a relatively highstrength can be exerted due to the increase of bond strength in the anchorage.

참고문헌 (Reference)

1 서수연, "콘크리트내에 표면매입 보강된 FRP 판의 부착강도" 한국콘크리트학회 24 (24): 415-422, 2012

2 Rezazadeh, M., "Transfer zone of prestressed CFRP reinforcement applied according to NSM technique for strengthening of RC structures" 79 (79): 581-594, 2015

3 Choi, H., "Partially bonded nearsurface-mounted CFRP bars for strengthened concrete T-beams" 25 : 2441-2449, 2011

4 EI-Hacha, R., "Near surface-mounted fiber-reinforced polymer reinforcements for flexural strengthening of concrete structures" 101 (101): 717-726, 2004

5 Hassan, T., "Investigation of bond in concrete structures strengthened with near surface mounted carbon fiber reinforced polymer strips" 7 (7): 248-257, 2003

6 Ali, M., "Interfacial stress transfer of near surface-mounted FRP-toconcrete joints" 30 (30): 1861-1868, 2008

7 Seracino, R., "Generic debonding resistance of EB and NSM plate-to-concrete joints" 11 (11): 62-70, 2007

8 Sharaky, I., "Flexural response of reinforced concrete(RC)beams strengthened with near surface mounted(NSM)fibre reinforced polymer(FRP)bars" 109 : 8-22, 2014

9 Chahrour, A., "Flexural response of reinforced concrete beams strengthened with end-anchored partially bonded carbon fiber-reinforced polymer strips" 9 (9): 170-177, 2005

10 Yost, J., "Flexural behavior of concrete beams strengthened with near surface-mounted CFRP strips" 104 (104): 430-437, 2007

11 Lorenzis, D., "Flexural and shear strengthening of reinforced concrete structures with near surface mounted FRP rods" 521-528, 2000

12 Al-Mahmoud, F., "Failure modes and failure mechanisms of RC members strengthened by NSM CFRP composites—Analysis of pull-out failure mode" 43 (43): 1893-1901, 2012

13 Nanni, A., "FRP reinforcement for bridge structures. Proceedings of structural engineering conference beams" 5 (5): 12-17, 2000

14 "Externally bonded FRP reinforcement for RC structures. Technical report on the design and use of externally Bonded Fibre reinforced Polymer Reinforcement (FRP EBR) for reinforced Concrete Structures" International Federation for Structural Concrete 2001

15 Seracino, R., "Bond strength of near-surface mounted FRP strip-to-concrete joints" 11 (11): 401-409, 2007

16 Seo, S., "Bond strength of near surface-mounted FRP plate for retrofit of concrete structures" 95 : 719-727, 2013

17 Lee, D., "Bond characteristics of various NSM FRP reinforcements in concrete" 17 (17): 117-129, 2013

18 Ceroni, F., "Bond behavior of FRP NSM systems in concrete elements" 43 (43): 99-109, 2012

19 Choi, H., "Analysis of the flexural behavior of partially bonded FRP strengthened concrete beams" 12 (12): 375-386, 2008

20 "ACI Committee 440, Guide for the design and construction of concrete reinforced with FRP bars (ACI 440.2R-02)"

21 Jose, S., "A pullout test for the near surface mounted CFRP-concrete bond characterization" 13 : 2007