Journal of the Korea institute for structural maintenance and inspection (한국구조물진단유지관리공학회 논문집)

Korea Institute for Structural Maintenance Inspection (한국구조물진단유지관리공학회)
권호 표지
DOI QR코드

DOI QR Code

Experimental Study on GFRP Reinforcing Bars with Hollow Section

중공형 GFRP 보강근의 인장성능 실험연구

  • 유영준 (한국건설기술연구원 인프라구조연구실) ;
  • 박기태 (한국건설기술연구원 인프라구조연구실) ;
  • 서동우 (한국건설기술연구원 인프라구조연구실) ;
  • 황지현 (한국건설기술연구원 인프라구조연구실)
  • Received : 2014.04.28
  • Accepted : 2014.06.12
  • Published : 2015.01.30
Download PDF
⟨ Previous Next ⟩

Abstract

Fiber-reinforced polymer (FRP) has been generally accepted by civil engineers as an alternative for steel reinforcing bars (rebar) due to its advantageous specific tensile strength and non-corrosiveness. Even though some glass fiber reinforced polymer (GFRP) rebars are available on a market, GFRP is still somewhat uncompetitive over steel rebar due to their high cost and relatively low elastic modulus, and brittle failure characteristic. If the price of component materials of GFRP rebar is not reduced, it would be another solution to increase the performance of each material to the highest degree. The tensile strength generally decreases with increasing diameter of FRP rebar. One of the reasons is that only fibers except for fibers in center resist the external force due to the lack of force transfer and the deformation of only outer fibers by gripping system. Eliminating fibers in the center, which do not play an aimed role fully, are helpful to reduce the price and finally FRP rebar would be optimized over the price. In this study, the effect of the hollow section in a cross-section of a GFRP rebar was investigated. A GFRP rebar with 19 mm diameter was selected and an analysis was performed for the tensile test results. Parameter was the ratio of hollow section over solid cross-section. Four kinds of hollow sections were planned. A total of 27 specimens, six specimens for each hollow section and three specimens with a solid cross-section were manufactured and tested. The change by the ratio of hollow section over solid cross-section was analyzed and an optimized cross-section design was proposed.

섬유복합체 (Fiber Reinforced Polymer, FRP)는 비강도가 높고, 비부식성 재료라는 특징을 가지고 있어서 건설 분야에서 철근을 대체할 수 있는 보강근 재료로 인식되고 있다. 몇몇 유리섬유 복합체 (Glass FRP, GFRP) 보강근이 상용화되어 있지만 GFRP는 철근에 비해 가격이 비싸고 상대적으로 낮은 탄성계수와 취성 파괴 특성 때문에 다소 경쟁력이 떨어진다. GFRP 보강근의 재료가격을 낮출 수 없다면 사용된 재료의 성능을 최대로 하여 보강근의 성능을 높이는 것이 상대적인 가격을 낮추는 방법이 될 수 있다. 일반적으로 FRP 보강근의 직경이 커질수록 인장강도는 감소하는 것으로 알려져 있다. 이의 원인 중 하나는 보강근이 인장을 받을 때 외력이 중앙에 위치한 섬유에 충분히 전달되지 못하여 외측에 위한 섬유들만이 인장에 저항하기 때문이다. 따라서 본연의 역할을 수행하지 못하는 섬유는 제거함으로써 보강근의 단가를 낮추면서 보강근이 소정의 성능을 발휘하도록 한다면 가격대비 성능이 최적화된 FRP 보강근을 제작할 수 있다. 본 연구에서는 직경 19 mm의 GFRP 보강근에 대해 단면 내에 중공이 존재하는 경우 중공비율에 따른 인장특성의 변화를 실험적으로 관찰하였다. 중공이 없는 GFRP 보강근 세 개, 네 가지 중공비율에 대해 각각 여섯 개의 GFRP 보강근 시편을 준비하여 인장실험을 실시하였으며 결과 분석을 통하여 인장특성 변화를 도출하였으며 이를 바탕으로 최적의 중공비율을 제안하였다.

Keywords

References

  1. Ahmadi, M. S., Johari, M. S., Sadighi, M., and Esfandeh, M. (2009), An experimental study on mechanical properties of GFRP braid-pultruded composite rods, eXPRESS Polymer Letters, 3(9), 560-568. https://doi.org/10.3144/expresspolymlett.2009.70
  2. American Concrete Institute (ACI) (1996), State-of-the-Art Report on Fiber Reinforced Plastic (FRP) Reinforcement for Concrete Structures, ACI 440R-96, Committee 440, 3.
  3. Bank, L. C. (2006), Composites for Construction: Structural Design with FRP materials, John Wiley & Sons, Inc..
  4. Daniel, I. M., and Ishai, O. (1994), Engineering Mechanics of Composite Materials, Oxford University press, 72-85.
  5. Hughes Brothers Inc. (2014), http://aslanfrp.com/aslan100/Resources/Aslan100a.pdf, confirmed at 2014.04.24.
  6. ISIS Canada (2001), Design Manual 3: Reinforcing concrete structures with fiber reinforced polymers, The Canadian Network of Centers of Excellence on Intelligent Sensing for Innovative Structures.
  7. Johnson, D. T. C. (2009), Investigation of glass fibre reinforced polymer reinforcing bars as internal reinforcement for concrete structures, MSc Thesis, Department of Civil Engineering, University of Toronto.
  8. Ko, F. K., Somboonsong, W., and Harris, H. G. (1997), Fiber architecture based design of ductile composite rebars for concrete structures, Proceedings of the 11th International Conference of Composite Materials, Ed. Scott, M.L, Gold Coast, Austrailia, 4.
  9. Korea Institute of Construction Technology (KICT) (2006), Design and construction technology for concrete structures using advanced composite materials, Interim report submitted to the Korea Research Council of Public Science and Technology, Korea (in Korean).
  10. Lee, D. G., Jeong, M. Y., Choi, J. H., Cheon, S. S., Chang, S. H., and Oh, J. H. (2007), Composite materials, Hongrung publishing company, Seoul, 166.
  11. Renee, C., and Yunping, X. (2003), THE BEHAVIOR OF FIBER-REINFORCED POLYMER REINFORCEMENT IN LOW TEMPERATURE ENVIRONMENTAL CLIMATES, Report No. CDOT-DTD-R-2003-4, Department of Civil, Environmental & Architectural Engineering, University of Colorado.
  12. Wang, Z., Goto, Y., and Joh, O. (1999), Bond strength of various types of fiber reinforced plastic rods, Fourth International Symposium on Fiber Reinforced Polymer Reinforcement for Reinforced Concrete Structures, SP-188, Editors Charles W., Dolan, Sami H. R., and Antonio N., 1127.
  13. Zenon, A., and Kypros, P. (2004), Bond behavior of fiber reinforced polymer bars under direct pullout conditions, Journal of composites for construction, 8, 173-181. https://doi.org/10.1061/(ASCE)1090-0268(2004)8:2(173)