DOI QR코드

DOI QR Code

Shear Capacity of the RC T Beams Strengthened for Shear with NSM FRP Strips

FRP 판으로 표면매립 전단보강된 철근콘크리트 T형 보의 전단성능

  • Seo, Soo-Yeon (Department of Architectural Engineering, Korea National University of Transportation)
  • 서수연 (한국교통대학교 건축학부)
  • Received : 2022.12.04
  • Accepted : 2022.12.11
  • Published : 2022.12.31

Abstract

The purpose of this study is to define the shear reinforcing effect of Near-Surface-Mounted (NSM) FRP strips in reinforced concrete (RC) member through a test. Three T shaped RC beams were made and two of them were strengthened with NSM FRP strips for increase shear strength. And those were tested to find the shear strengthening effect. In the test, two case of shear strengthening methods were considered such as 1) with NSM FRP strips having full embedded length and 2) with NSM FRP strips having some what short embedded length and additional externally bonded FRP sheet. As a result, the shear strengthening effect could be obtained when the NSM FRP strips are embedded to have full length up to the bottom of slab. However the shear strength was not increased in the case of having somewhat short embedded length of NSM FRP strips even additional EB sheet was enhanced.

본 연구의 목적은 실험을 통하여 FRP를 이용한 철근콘크리트 부재의 표면매립 전단보강 효과를 규명하는 것이다. 연구목적을 달성하기 위하여, 3개의 철근콘크리트 T형 보를 제작하고 이중 두 개의 보에 대해서 표면매립 보강방법으로 FRP를 전단보강한 뒤 실험을 통하여 보강효과를 규명하였다. 실험에서 두 가지의 전단보강방법을 고려하였는데, 첫째 충분한 매립길이를 가진 표면매립 (NSM) 보강, 둘째 다소 짧은 표면매립길이를 가지지만 추가의 표면부착 (EB) 보강을 한 경우이다. 연구결과, FRP strip을 이용한 표면매립길이를 플랜지 하부까지 길게 확보할 경우에는 충분한 전단보강효과가 발휘되는 것으로 나타났다. 반면에 충분한 매립길이가 확보되지 않은 경우에는 FRP sheet로 추가 보강하더라도 전단보강효과가 나타나지 않는 것으로 나타났다.

Keywords

Acknowledgement

본 연구는 2022년도 과학기술정보통신부 기초연구지원사업 (No.2022R1A2C2004460)에 의해 수행되었음.

References

  1. ACI Committee 440-2R (2017), Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures, American Concrete Institute.
  2. Choi, J., Kim, M., Kim, H., and Lee, Y. (2013), Shear Strengthening Effect of Reinforced Concrete Beam Strengthened with CFRP Plate, Journal of the Architectural Institute of Korea, 24(4), 15-22.
  3. Han, S., Hong, K., Shin, B. Lin, J., and Kwak, S. (2011), Characteristics of Shear Behavior of Reinforced Concrete Beams Strengthened with Near Surface Mounted CFRP Strips, Journal of the Korea Institute for Structural Maintenance and Inspection, 15(5), 178-189. https://doi.org/10.11112/JKSMI.2011.15.5.178
  4. Hong, K., Lee, S., Han, S., and Kang, P. (2018), Long-term Flexural Behavior of RC Beams Strengthened in Flexure with NSM Fe-SMA Strips, Journal of the Korea Institute for Structural Maintenance and Inspection, 22(3), 103-110. https://doi.org/10.11112/JKSMI.2018.22.3.103
  5. Lee, B. (2014), Analysis of Reinforced Concrete Beams Strengthened with Near Surface Mounted CFRP Strip for Flexure, Chungbuk National University.
  6. Lee, H. Lee, C., Kwon, W., Kim, W., Baek, S., and Kwak, Y. (2008), Shear Strengthening Effect of Reinforced Concrete Beam Strengthened with CFRP Plate, Journal of the Architectural Institute of Korea, 24(4), 15-22.
  7. Lim, D.H., and Kwon, Y.S.. (2009). An Experimental Study on the Shear Behavior of RC Beams Strengthened with Near Surface Mounted and Externally Bonded CFRP Strips, Journal of the Korea Concrete Institute, 21(3), 337-345. https://doi.org/10.4334/JKCI.2009.21.3.337
  8. Kim, S. (2015), CFRP-bar NSM system of reinforced concrete members Study on Bonding and Flexural Behavior, Yeungnam University.
  9. Ministry of Land, Infrastructure and Transport. (2021), Design code for Shear and Torsion of Concrte Structure, KDS 14 20 22.
  10. Seo, S. (2012), Bond Strength of Near Surface-Mounted FRP Plate in RC Member, Journal of the Korea Concrete Institute, 24(4), 415-422. https://doi.org/10.4334/JKCI.2012.24.4.415
  11. Seo, S. Choi, K., and Kwon, Y. (2012), Retrofit Capacity of Near-Surface-Mounted RC Beam by using FRP Plate, Journal of the Korea Institute for Structural Maintenance and Inspection, 16(1), 18-26. https://doi.org/10.11112/JKSMI.2012.16.1.018
  12. Seo, S., Feo, L., and Hui D. (2013b), Bond Strength of Near-Surface-Mounted FRP Plate for Retrofit of Concrete Structures, Composite Structures, 95, 719-727. https://doi.org/10.1016/j.compstruct.2012.08.038
  13. Seo, S., and Kim, M. (2013), Bond Strength of Near Surface-Mounted FRP Plate in Concrete Corresponding to Space and Bond Length, Journal of the Korea Concrete Institute, 25(1), 37-43. https://doi.org/10.4334/JKCI.2013.25.1.037
  14. Seo, S., Lee, M., and Feo, L. (2016), Flexural Analysis of RC Beam Strengthened by Partially De-bonded NSM FRP Strip, Composite Part B, 101(15), 21-30. https://doi.org/10.1016/j.compositesb.2016.06.056