KSCE Journal of Civil and Environmental Engineering Research (대한토목학회논문집)

Korean Society of Civil Engeneers (대한토목학회)
권호 표지
DOI QR코드

DOI QR Code

A Study on the Basic Development Length of GFRP Rebar With Ribs

이형 GFRP 보강근의 기본정착길이에 대한 연구

  • 문도영 (경성대학교 토목공학과)
  • Received : 2010.07.07
  • Accepted : 2010.08.30
  • Published : 2010.10.31
Download PDF
⟨ Previous Next ⟩

Abstract

GFRP rebar with ribs resemble those of deformed steel rebar was developed in 2005. It was reported that ribs of the GFRP rebar were sheared off due to the lower shear strength of polymer. In this study, the basic development length of the GFRP rebar was investigated through pull-out tests, models specified in ACI440.1R-03 and -06, and empirical model derived by Cosenza et al. (2002). As a results of pull-out tests, the critical embeddment length, which is defined as the length when failure mode is changed from pull-out to bar fracture, was 20 times of bar diameter for GFRP rebar and was 15 times for steel rebar. It is believed that the basic development of the GFRP rebar is 21 times of bar diameter, which is determined from the application of average bond strength into the model equation specified in ACI440.1R-03. Compared to the model equation in ACI440.1R-06, that in ACI440.1R-03 is recommendable for design purpose. The Cosenza et al.'s model underestimates the basic development length of the GFRP rebar.

국내에서 개발된 이형 GFRP 보강근은 표면에 구축된 이형의 전단강도가 콘크리트의 전단강도 보다 상대적으로 작아 이형철근과 달리 이형 자체가 전단파괴되는 파괴모드를 보이는 것으로 확인된바 있다. 본 논문에서는 이형을 갖는 GFRP 보강근의 기본정착길이를 인발실험과 설계모델식과 해석적 엄밀식을 통해 고찰하였다. 실험결과, 동일조건하에서 파괴모드가 변화되는 임계정착길이가 이형철근은 직경의 15배, 이형 GFRP 보강근은 20배인 것으로 나타났다. 또한 실험결과를 ACI440.1R-03 설계모델식에 적용하여 분석한 결과, 충분한 횡구속이 수반된 경우 직경 9 mm의 이형 GFRP 보강근의 기본정착길이는 직경의 21배인 것으로 나타났다. 반면, ACI440.1R-06에 제시된 기본정착길이 모델은 실험결과에 비하여 너무 과대한 기본정착길이를 요구하는 것으로 나타났다. Cosenza 등(2002)의 모델은 실험결과에 비하여 더 적은 기본 정착길이를 요구하므로, 설계목적의 사용은 제한적인 것으로 판단되었다.

Keywords

References

  1. 문도영, 심종성, 오홍섭(2006) 초단유리섬유와 에폭시 혼합물을 이용한 FRP보강근 표면성형기법 연구, 대한토목학회논문집, 대한토목학회, 제26권 제4A호, pp. 775-785.
  2. 문도영, 오홍섭, 심종성(2005) 이형리브를 갖는 GFRP 보강근의 부착성능에 관한 실험적 연구, 대한토목학회논문집, 대한토목학회, 제25권 제5A호, pp. 719-727.
  3. ACI 440.1R-03 (2003) Guide for the design and construction of concrete reinforced with FRP bars, ACI, Farmington Hills, Michigan, USA
  4. ACI 440.1R-06 (2006) Guide for the design and construction ofstructural concrete with FRP bars, ACI, Farmington Hills, Michigan, USA
  5. Achillides, Z. and Pilakoutas, K. (2004) Bond behavior of fiber reinforced polymer bars under direct pullout conditions. Journal of Composite for Construction, Vol 8, No. 2, pp. 173-181. https://doi.org/10.1061/(ASCE)1090-0268(2004)8:2(173)
  6. Al-Zahrani, M.M, Al-Dulaijan, S.U., Nanni, A., Bakis, C.E., and Boothby, T.E. (1999) Evaluation of bond using FRP rods with axisymmetric deformations. Construction and Building Materials, Vol 13, pp. 299-309. https://doi.org/10.1016/S0950-0618(99)00038-0
  7. Bakis, C.E., Uppuluri, V.S., Nanni, A., and Boothby, T.E. (1998) Analysis of bonding mechanisms of smooth and lugged FRP rods embedded in concrete, Composites Science and Technology, Vol. 58, Issue 8, pp. 1307-1319. https://doi.org/10.1016/S0266-3538(98)00016-5
  8. Cosenza, E., Manfredi, G., and Realfonzo, R. (1997) Behavior and modeling of bond of FRP rebars to concrete, Journal of Composites for Construction, ASCE, Vol. 1, No. 2, pp. 40-51. https://doi.org/10.1061/(ASCE)1090-0268(1997)1:2(40)
  9. Cosenza, E., Manfredi, G., and Realfonzo, R. (2002) Development length of FRP straight rebars, Composites Part B: Engineering, Vol. 33, Issue 7, pp. 493-504. https://doi.org/10.1016/S1359-8368(02)00051-3
  10. Elegehausen, R. Popov, E.P., and Bertero, V.V. (1983) Local bond stress-slip relationships of deformed bars under generalized excitations, Report No. 83/23, EERC, Univ. of California, Berkeley.
  11. Marval, L.J., Cox, J.V., and Cochran, K.B. (2003) Bond between carbon fibre reinforced polymer bars and concrete. I: Experimental study, Journal of Composites for Construction, Vol. 7, pp. 154-163. https://doi.org/10.1061/(ASCE)1090-0268(2003)7:2(154)
  12. Moon, D.Y. (2008) Bond behaviour of newly developed deformed GFRP bars. Ph. D Dissertation, Hanyang University, Seoul, Korea.
  13. Moon, D.Y, Usama, A.E., and Benmokrane, B. (2009) Effective surface deformation height and bond rigidity of gfrp reinforcing bars with ribs, Polymers & Polymer Composites, Vol. 17, No. 3, pp. 161-171.
  14. Okelo, R. and Yuan, R.L. (2005) Bond strength of fiber reinforced polymer rebars in normal strength concrete. Journal of Composites for Construction, Vol. 9, No. 3, pp. 203-213. https://doi.org/10.1061/(ASCE)1090-0268(2005)9:3(203)
  15. Wambeke, B. and Shield, C. (2006) Development length of glass fiber reinforced polymer bars in concrete, ACI Structural Journal, Vol. 103, No. 1, pp. 11-17.
  16. Zhang, B. and Benmokrane, B. (2002) Pullout bond properties of fiber-reinforced polymer tendons to grout. Journal of Materials in Civil Engineering, Vol. 15, No. 5, pp. 399-408.