Journal of the Korea Concrete Institute (콘크리트학회논문집)

Korea Concrete Institute (한국콘크리트학회)
권호 표지
DOI QR코드

DOI QR Code

Evaluating Impact Resistance of Externally Strengthened Steel Fiber Reinforced Concrete Slab with Fiber Reinforced Polymers

섬유 보강재로 외부 보강된 강섬유 보강 콘크리트 슬래브의 충격저항성능 평가

  • Yoo, Doo-Yeol (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Min, Kyung-Hwan (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Lee, Jin-Young (School of Civil, Environmental and Architectural Engineering, Korea University) ;
  • Yoon, Young-Soo (School of Civil, Environmental and Architectural Engineering, Korea University)
  • 류두열 (고려대학교 건축사회환경공학부) ;
  • 민경환 (고려대학교 건축사회환경공학부) ;
  • 이진영 (고려대학교 건축사회환경공학부) ;
  • 윤영수 (고려대학교 건축사회환경공학부)
  • Received : 2012.01.18
  • Accepted : 2012.03.21
  • Published : 2012.06.30
Download PDF
⟨ Previous Next ⟩

Abstract

Recently, as construction technology improved, concrete structures not only became larger, taller and longer but were able to perform various functions. However, if extreme loads such as impact, blast, and fire are applied to those structures, it would cause severe property damages and human casualties. Especially, the structural responses from extreme loading are totally different than that from quasi-static loading, because large pressure is applied to structures from mass acceleration effect of impact and blast loads. Therefore, the strain rate effect and damage levels should be considered when concrete structure is designed. In this study, the low velocity impact loading test of steel fiber reinforced concrete (SFRC) slabs including 0%~1.5% (by volume) of steel fibers, and strengthened with two types of FRP sheets was performed to develop an impact resistant structural member. From the test results, the maximum impact load, dissipated energy and the number of drop to failure increased, whereas the maximum displacement and support rotation were reduced by strengthening SFRC slab with FRP sheets in tensile zone. The test results showed that the impact resistance of concrete slab can be substantially improved by externally strengthening using FRP sheets. This result can be used in designing of primary facilities exposed to such extreme loads. The dynamic responses of SFRC slab strengthened with FRP sheets under low velocity impact load were also analyzed using LS-DYNA, a finite element analysis program with an explicit time integration scheme. The comparison of test and analytical results showed that they were within 5% of error with respect to maximum displacements.

최근 건설기술의 발전에 따라 구조물이 대형화, 고층화, 장대화되고 있으며, 동시에 다양한 기능을 수행하고 있다. 그러나 요즘 들어 그 빈도수가 증가하고 있는 충돌 사고나 테러에 의한 폭발, 화재 등에 의한 극한하중이 상기의 구조물에 작용할 경우, 구조물의 손상뿐만 아니라 인명과 재산의 피해 정도가 상당히 커질 수 있다. 특히, 충격이나 폭발하중은 구조물에 작용하는 압력 또는 하중이 매우 짧은 시간에 발생하게 되고, 이러한 하중을 받는 구조물은 준-정적(quasi-static) 하중을 받는 구조물과는 다른 응답을 나타내게 되며 반드시 변형률 속도와 손상 효과를 고려해서 설계가 이루어져야 한다. 그러므로 이 연구에서는 콘크리트 슬래브의 충격저항성능 향상을 위해서 강섬유를 전체 부피의 0%에서 1.5%까지 혼입하고, 두 가지 종류의 FRP 시트를 인장부에 보강하여 저속 충격하중에서의 휨 실험을 수행하였다. 실험 결과 FRP 시트를 인장부에 보강할 경우에 최대 충격하중 및 소산에너지, 파괴 시의 타격 횟수가 증가하였으며, 최대 처짐 및 회전각은 감소하여 충격저항성능이 크게 향상되는 것으로 나타났다. 이러한 결과는 추후 극한하중에 노출될 수 있는 주요 시설물의 설계 시 유용하게 사용될 수 있을 것으로 판단된다. 또한, 이 논문에서는 두 가지 종류의 FRP 시트로 보강된 강섬유 보강 콘크리트 슬래브의 저속 충격하중에서의 동적응답을 해석하기 위하여 외연적 시간적분에 기초한 유한요소해석 프로그램인 LS-DYNA를 사용하였으며, 해석 결과 오차율 5% 이내로 비교적 정확하게 최대 처짐을 예측하는 것으로 나타났다.

Keywords

References

  1. Krauthammer, T., Modern Protective Structures, CRC Press, 2007.
  2. Malvar, L. J., Crawford, J. E., and Morrill, K. B., "Use of Composites to Resist Blast," Journal of Composites for Construction, Vol. 11, No. 6, 2007, pp. 601-610. https://doi.org/10.1061/(ASCE)1090-0268(2007)11:6(601)
  3. Buchan, P. A. and Chen, J. F., "Blast Resistance of FRP Composites and Polymer Strengthened Concrete and Masonry Structures - A State-of-the-art Review," Composites Part B, Vol. 38, Nos. 5-6, 2006, pp. 509-522.
  4. Min, K. H., Yang, J. M., Yoo, D. Y., and Yoon, Y. S., "Flexural and Punching Performances of FRP and Fiber Reinforced Concrete on Impact Loading," The 5th International Conference on FRP Composites in Civil Engineering, Beijing, China, 2010, pp. 410-414.
  5. Silva, P. F. and Lu, B., "Improving the Blast Resistance Capacity of RC Slabs with Innovative Composite Materials," Composites Part B, Vol. 38, Nos. 5-6, 2007, pp. 523-534. https://doi.org/10.1016/j.compositesb.2006.06.015
  6. Mosalam, K. M. and Mosallam, A. S., "Nonlinear Transient Analysis of Reinforced Concrete Slabs Subjected to Blast Loading and Retrofitted with CFRP Composites," Composites Part B, Vol. 32, No. 8, 2001, pp. 623-636. https://doi.org/10.1016/S1359-8368(01)00044-0
  7. ACI Committee 440, "Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures," ACI 440.2R-02, American Concrete Institute, MI, USA, 2002, pp. 1-45.
  8. Teng, J. G., Chen, J. F., Smith, S. T., and Lam, L., FRP Strengthened RC Structures, John Wiley & Sons, West Sussex, England, 2002, pp. 31-46.
  9. Choi, H. and Krauthammer, T., "Development of Progressive Collapse Analysis Procedure Considering Local Buckling Effects," The 1st International Conference on Design and Analysis of Protective Structures against Impact/Impulsive/ Shock Loads (DAPSIL), Tokyo, Japan, 2003, pp. 481- 488.
  10. 김호진, 남진원, 김성배, 김장호, 변근주, "폭발하중을 받는 콘크리트 벽체 구조물의 보강 성능에 대한 해석적 분석," 콘크리트학회 논문집, 19권, 2호, 2007, pp. 241-250. https://doi.org/10.4334/JKCI.2007.19.2.241
  11. Nam, J. W., Kim, H. J., Kim, S. B., Yi, N. H., and Kim, J. H. J., "Numerical Evaluation of the Retrofit Effectiveness for GFRP Retrofitted Concrete Slab subjected to Blast Pressure," Composite Structures, Vol. 95, No. 5, 2010, pp. 1212-1222.
  12. 이진영, 김미혜, 민경환, 윤영수, "저속 충격하중에서의 FRP Sheet 및 강섬유 보강 콘크리트의 거동 해석," 구조 물진단학회지, 15권, 4호, 2011, pp. 155-164.
  13. Teng, T. L., Chu, Y. A., Chang, F. A., Shen, B. C., and Cheng, D. S., "Development and Validation of Numerical Model of Steel Fiber Reinforced Concrete for High-Velocity Impact," Computational Materials Science, Vol. 42, No. 1, 2008, pp. 90-99. https://doi.org/10.1016/j.commatsci.2007.06.013
  14. Wang, Z. L., Konietzky, H., and Huang, R. Y., "Elastic-Plastic- Hydrodynamic Analysis of Crater Blasting in Steel Fiber Reinforced Concrete," Theoretical and Applied Fracture Mechanics, Vol. 52, No. 2, 2009, pp. 111-116. https://doi.org/10.1016/j.tafmec.2009.08.005
  15. Comite Euro-International du Beton (CEB), CEB-FIP Model Code 1990, Redwood Books, Wiltshire, UK, 1993.
  16. Wang, S., Zhang, M. H., and Quek, S. T., "Effect of High Strain Rate Loading on Compressive Behavior of Fibre- Reinforced High-Strength Concrete," Magazine of Concrete Research, Vol. 63, No. 11, 2011, pp. 813-827. https://doi.org/10.1680/macr.2011.63.11.813
  17. Malvar L. J. and Ross C. A., "Review of Strain Rate Effects for Concrete in Tension," ACI Materials Journal, Vol. 95, No. 6, 1998, pp. 735-739.
  18. Livermore Software Technology Corporation (LSTC) LSDYNA, Keyword User's Manual Version 971, 2007.
  19. Mutalib, A. A. and Hao, H., "Numerical Analysis of FRPComposite- Strengthened RC Panels with Anchorages against Blast Loads," Journal of Performance of Construction Facilities, Vol. 25, No. 5, 2011, pp. 360-372. https://doi.org/10.1061/(ASCE)CF.1943-5509.0000199
  20. Kim, H. J., Yi, N. H., Kim, S. B., Nam, J. W., Ha, J. H., and Kim, J. H. J., "Debonding Failure Analysis of FRP-Retrofitted Concrete Panel under Blast Loading," Structural Engineering and Mechanics, Vol. 38, No. 4, 2011, pp. 479- 501. https://doi.org/10.12989/sem.2011.38.4.479
  21. Yaz c , S., Inan, G., and Tabak, V., "Effect of Aspect Ratio and Volume Fraction of Steel Fiber on the Mechanical Properties of SFRC," Construction and Building Materials, Vol. 21, No. 6, 2007, pp. 1250-1253. https://doi.org/10.1016/j.conbuildmat.2006.05.025
  22. Eren, Ö. and Celik, T., "Effect of Silica Fume and Steel Fibers on Some Properties of High-Strength Concrete," Construction and Building Materials, Vol. 11, Nos. 7-8, 1997, pp. 373-382. https://doi.org/10.1016/S0950-0618(97)00058-5
  23. Kayali, O., "Effect of High Volume Fly Ash on Mechanical Properties of Fiber Reinforced Concrete," Materials and Structures, Vol. 37, No. 5, 2004, pp. 318-327. https://doi.org/10.1007/BF02481678
  24. Ati¸s, C. D. and Karaham, O., "Properties of Steel Fiber Reinforced Fly Ash Concrete," Construction and Building Materials, Vol. 23, No. 1, 2009, pp. 392-399. https://doi.org/10.1016/j.conbuildmat.2007.11.002
  25. Sukontasukkul, P. and Mindess, S., "The Shear Fracture of Concrete under Impact Loading Using End Confined Beams," Materials and Structures, Vol. 36, No. 6, 2003, pp. 372-378. https://doi.org/10.1007/BF02481062
  26. Fujikake, K., Li, B., and Soeun, S., "Impact Response of Reinforced Concrete Beam and Its Analytical Evaluation," Journal of Structural Engineering, ASCE, Vol. 135, No. 8, 2009, pp. 938-950. https://doi.org/10.1061/(ASCE)ST.1943-541X.0000039
  27. Ngo, T., Mendis, P., Gupta, A., and Ramsay, J., "Blast Loading and Blast Effects on Structures-An Overview," Electronic Journal of Structural Engineering, Special Issue: Loading on Structures, 2007, pp. 76-91.
  28. Zhou, X. Q., Kuznetsov, V. A, Hao, H., and Waschl, J., "Numerical Prediction of Concrete Slab Response to Blast Loading," International Journal of Impact Engineering, Vol. 35, No. 10, 2008, pp. 1186-1200. https://doi.org/10.1016/j.ijimpeng.2008.01.004
  29. 이경구, "폭발하중을 받는 강재압축재의 잔여저항성능 평가," 대한건축학회지, 26권,10호, 2010, pp. 37-44.

Cited by

  1. Experimental Evaluation of Bi-directionally Unbonded Prestressed Concrete Panel Impact-Resistance Behavior under Impact Loading vol.25, pp.5, 2013, https://doi.org/10.4334/JKCI.2013.25.5.485
  2. Fibrous and composite materials for blast protection of structural elements—A state-of-the-art review vol.32, pp.19, 2013, https://doi.org/10.1177/0731684413498297
  3. Effect of Different Energy Frames on the Impact Velocity of Strain Energy Frame Impact Machine vol.27, pp.4, 2015, https://doi.org/10.4334/JKCI.2015.27.4.363