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

Mechanical Performance Evaluation of RC Beams with FRP Hybrid Bars under Cyclic Loads

FRP 하이브리드 보강근을 가지는 RC보의 반복하중에 대한 역학적 성능 평가

  • 황철성 (가천대학교 토목환경공학과) ;
  • 박재성 (한남대학교 건설시스템공학과) ;
  • 박기태 (한국건설기술연구원) ;
  • 권성준 (한남대학교 건설시스템 공학과)
  • Received : 2016.08.16
  • Accepted : 2016.10.20
  • Published : 2017.01.01
Download PDF
⟨ Previous Next ⟩

Abstract

In the present work, a mechanical performances under cyclic loading in RC (Reinforced Concrete) beams with normal steel and FRPH (Fiber Reinforced Plastic Hybrid) bar are investigated. For the work, RC beam members with $200{\times}200{\times}2175mm$ of geometry and 24 Mpa of design strength are prepared, and 4-point-bending tests are performed for evaluation of cracking, yielding, and ultimate loads. Through static loading test, 48.9kN and 36.0 kN of yielding loads are measured for normal RC and FRPH beam, respectively. They have almost same ultimate load of 50.0 kN. Typical tension hardening behavior is observed in FRPH beam, which is caused by the behavior of FRPH bar with tension hardening. In cyclic loading conditions, FRPH beam has more smaller crack width and scattered crack pattern, and it shows more elastic recovery than normal RC beam. The energy dissipation ratio in FRPH beam is 0.83, which is greater than 0.62 in normal RC beam and it shows more effective resistance to cyclic loadings.

본 연구는 일반철근과 FRPH Bar를 주철근으로 한 철근 콘크리트 보부재를 대상으로 정적실험 및 반복하중 재하실험을 수행하여 에너지 소산성능 및 반복하중 저항성능을 분석하였다. 실험을 위하여 24MPa의 설계강도를 가진 콘크리트 보부재($200{\times}200{\times}2175mm$)를 제작하였으며, 4점 휨 시험을 수행하여 초기균열하중, 항복하중, 파괴하중을 측정하였다. 정적하중 재하실험을 통해 각 시험체에 대한 항복하중과 파괴강도를 측정하였는데, 항복하중은 RC보에서는 48.9kN, FRPH 보에서는 36kN으로 평가되었으며, 파괴하중은 두 시험체 모두 50kN의 강도를 보였다. 정적하중-처짐 결과에서는 FRPH 보는 RC보에 비하여 인장경화특성을 나타내는데, 이는 FRPH bar의 인장경화 특성에 기인한다. 반복하중하에서 FRPH bar를 가진 보에서는 일반 RC보와는 다르게 작은 폭의 균열이 넓게 발생하였으며, 우수한 처짐 복원력을 나타내었다. 정적 동적 에너지 비율을 이용한 에너지 소산능력에서는 RC보에서는 0.62, FRPH 보에서는 0.83으로 평가되었으며, 이를 통해 FRPH를 가진 보부재에서 효과적으로 반복하중에 대하여 저항함을 알 수 있다.

Keywords

References

  1. ACI 440.1R-06 (2006), Guide for the Design and Construction of Structural Concrete Reinforce with FRP Bars, ACI Committee 440.
  2. Alkhrdaji, T., Nanni, A., Chen, G., and Barker, M. (1999), Upgrading the transportation Infrastructure : Solid RC Decks Strengthened with FRP, Concrete International, ACI, 21(10), 37-41.
  3. Bautista, A. and Gonzalez, J. A. (1996), Analysis of the Protective Efficiency of Galvanizing against Corrosion of Reinforcements Embedded in Chloride Contaminated Concrete, Cement and Concrete Research, 26(2), 215-224. https://doi.org/10.1016/0008-8846(95)00215-4
  4. Broomfield, J. P. (1997), Corrosion of Steel in Concrete: Understanding, Investigation and Repair, E&FN, London, 1-15.
  5. Choi, S. J., Mun, J. M., Park, K. T., Park, C. W., and Kwon, S.-J. (2015), Characteristics of Flexural Capacity and Ultrasonic in RC Member with Corroded Steel and FRP Hybrid Bar, Journal of Contents Institute, 15(8), 397-407.
  6. Kang, B. S., Shim, H. S., and Hwang, S. C. (2001), Fatigue Behavior of RC Elements under High Cyclic Loading, Journal of the Korea Concrete Institute, 2001(11), 1161-1166.
  7. KICT (2013), Development of Enhancing Life Span Technology for Waterfront Structures using FRP Hybrid Bars.
  8. Lee, C. S., Bae, I. Y., Kim, K. J., Moon, K. M., and Lee, M. H. (2004), Properties Analysis of Environment Friendly Electrodeposit Films Formed at Various Current Density Conditions in Natural Seawater, Journal of Korea Institute of Surface Engineering, 37(5), 253-262.
  9. Lee, M. H. and Ryu, H. J. (2004), Surface Coating Method of Environment-Friendly Calcareous Deposit formed in Natural Seawater, Fourth International Symposium on Biomimetic Materials Processing, 4, 94.
  10. Nanni, A., Micelli, F., and La-Tegola, A. (2001), Durability of GFRP Bars Subjected to Aggressive Environment, Proceeding of 22nd International SAMPLE Europe Conference, Paris, 431-443.
  11. Nanni, A., Nenninger, J., Ash, K., and Liu, J. (1997), Experimental Bond Behavior of Hybrid Rods for Concrete Reinforcement, Structural Engineering and Mechanics, 5(4), 339-354. https://doi.org/10.12989/sem.1997.5.4.339
  12. Oh, B. H., Han, S. H., Lee, H. J., Kim, J. S., and Shin, H. S. (1998), Shear Damage Behavior of Reinforced Concrete Beams under Fatigue Loads, Journal of the Korea Concrete Institute, 10(1), 143-151.
  13. Oh, B. H., Um, J. Y., and Kwon, J. H. (1992), An Experimental Study on Corrosion Resistance of Epoxy Coated Reinforcements, Journal of the Korea Concrete Institute, 4(4), 161-170.
  14. Oh, K. S., Mun, J. M., Park, K. T., and Kwon, S. J. (2016), Evaluation of Load Capacity Reduction in RC Beam with Corroded FRP Hybrid Bar and Steel, journal of the Korea Institute for Structural Maintenance and Inspection, 20(2), 10-17. https://doi.org/10.11112/JKSMI.2016.20.2.010
  15. Seo, D. W., Park, K. T., You, Y. J., and Kim, H. Y. (2013), Enhancement in Elastic Modulus of GFRP Bars by Material Hybridization, Engineering, 5, 865-869. https://doi.org/10.4236/eng.2013.511105
  16. Song, H. W., Back, S. J., Lee C. H., and Kwon, S. J. (2006), Service Life Prediction of Concrete Structures Under Marine Environment Considering Coupled Deterioration, Restoration of Buildings and Monuments, 12(4), 265-284.
  17. Thomas, M. D. A., and Bamforth, P. B. (1999), Modeling Chloride Diffusion in Concrete: Effect of Fly Ash and Slag, Cement and Concrete Research, 29, 487-495. https://doi.org/10.1016/S0008-8846(98)00192-6