Earthquakes and Structures

Techno-Press (테크노프레스)
권호 표지
DOI QR코드

DOI QR Code

Strengthening of deficient RC joints with diagonally placed external C-FRP ropes

  • Karayannis, Chris G. (Department of Civil Engineering, Democritus University of Thrace) ;
  • Golias, Emmanouil (Department of Civil Engineering, Democritus University of Thrace)
  • Received : 2020.12.29
  • Accepted : 2021.01.26
  • Published : 2021.01.25
⟨ Previous Next ⟩

Abstract

Deficient beam-column joints of reinforced concrete (RC) structures designed to older practices and codes often lead to destructive local or global failures. A strengthening technique for these joints based on the use of the new and innovative Carbon-FRP (C-FRP) ropes is presented and investigated. The C-FRP ropes are diagonally placed in superficial notches on the two sides of the joint. Two full scale external substandard joint subassemblages with the same characteristics, one unstrengthened and one strengthened with diagonally applied C-FRP ropes, are constructed and tested in cyclic loading. Special attention has been given to the elaboration of the acquired test measurements. The extracted conclusions are based on the comparative study of the hysteretic responses of the specimens, the observed maximum load envelopes, the comparisons of the joint body shear deformations as measured using diagonally mounted LVTDs, the calculated nominal principal stresses developed in the joint regions, the assessed joint damage as expressed by the damage index by Park and Ang and finally the calculated values of the equivalent damping ratio. From these comparisons it is concluded that application of diagonally mounted C-FRP ropes on the two sides of the joint body of exterior connections is an efficient easy-to-apply technique for the strengthening of substandard RC joints.

Keywords

References

  1. Al-Saadi N.T.K., Mohammed A., Al-Mahaidi R. and Sanjayan, J. (2019), "A state-of-the-art review: Near-surface mounted FRP composites for reinforced concrete structures", Construct. Build. Mater., 209, 748-769. https://doi.org/10.1016/j.conbuildmat.2019.03.121.
  2. Bakir, P.G. (2003), "Seismic resistance and mechanical behaviour of exterior beam-column joints with crossed inclined bars", Struct. Eng. Mech., 16(4), 493-517. https://doi.org/10.12989/sem.2003.16.4.493
  3. Berset, T., Gutowski, T. and Potrzebowski, J. (2016), "Multi-Purpose Heavy-Duty CFRP String as additional element of CFRP strengthening system Sika", COST Action TU1207 "Next Generation Design Guidelines for Composites in Construction", Action Meeting, Lodz Poland, April.
  4. Bracci J.M., Reinhorn A.M. and Mander J.M. (1992), "Evaluation of seismic retrofit of reinforced concrete frame structures: Part II - Experimental performance and analytical study of a retrofitted structural model", Technical Report, NCEER-92-0031, December.
  5. Chalioris C.E., Kosmidou, P.M.K., Papadopoulos, N. (2018), "Investigation of a new strengthening technique for RC deep beams using carbon FRP ropes as transverse reinforcements", Fibers, 6(3), https://doi:10.3390/fib6030052.
  6. Chalioris, C.E. and Bantillas K.E. (2017), "Shear strength of reinforced concrete beam-column joints with crossed inclined bars", Eng. Struct., 140, 241-255. https://doi.org/10.1016/j.engstruct.2017.02.072.
  7. Golias, E., Lindenthal, H., Schlüter, F.H. and Karabinis, A. (2020), "Ertüchtigung seismisch beschädigter Rahmenknoten aus Stahlbeton mittels FRP-Filamentbündelverbindungen", Bautechnik 97, H.4, S.268-278. https://doi.org/10.1002/bate.201900085.
  8. Kakaletsis, D.J., David, K.N. and Karayannis, C.G. (2011), "Effectiveness of some conventional seismic retrofitting techniques for bare and infilled R/C frames", Struct. Eng. Mech., 39(4), 499-520, https://doi10.12989/sem.2011.39.4.499.
  9. Kalogeropoulos, G.I. and Tsonos, A.G. (2014), "Effectiveness of R/C jacketing of substandard R/C columns with short lap splices", Struct. Monit. Maint., 1(14), 273-292, https://doi:10.12989/smm.2014.1.3.273.
  10. Karayannis, C.G. (2015), "Mechanics of external RC beamcolumn joints with rectangular spiral shear reinforcement: experimental verification", Meccanica, 50(2), 311-322, https://doi:10.1007/s11012-014-9953-6.
  11. Karayannis, C.G. and Golias. E. (2018), "Full scale tests of RC Joints with minor to moderate damage repaired using C-FRP sheets", Earthq. Struct., 15(6), 617-627, https://doi:10.12989/eas.2018.15.6.617.
  12. Karayannis, C.G. and Sirkelis, G.M. (2008), "Strengthening and rehabilitation of RC beam-column joints using carbon-FRP jacketing and epoxy resin injections", Earthq. Eng. Struct. Dyn., 37, 769-790. https://doi.org/10.1002/eqe.785.
  13. Karayannis, C.G., Chalioris, C.E. and Sideris, K.K. (1998), "Effectiveness of beam-column connection repair using epoxy resin injections", J. Earthq. Eng., 2(2), 217-240. https://doi.org/10.1080/13632469809350320
  14. Karayannis, C.G., Chalioris, C.E. and Sirkelis, G.M. (2008), "Local retrofit of exterior RC beam-column joints using thin RC jackets-An experimental study", Earthq. Eng. Struct. Dyn., 37, 727-746. https://doi.org/10.1002/eqe.783.
  15. Karayannis, C.G., Izzuddin, B.A. and Elnashai, A.S. (1994), "Application of adaptive analysis to reinforced concrete frames", J. Struct. Eng., ASCE, 120(10), 2935-2957, https://doi:10.1061/(ASCE)07339445(1994)120:10(2935).
  16. Karayannis, C.G., Kosmidou, P.M.K. and Chalioris, C.E. (2018), "Reinforced concrete beam with carbon-fiber-reinforced polymer bars - Experimental study", Fibers, 6(4). https://doi:10.3390/fib6040099.
  17. Marthong, C. (2019), "Rehabilitation and strengthening of exterior RC beam-column connections using epoxy resin injection and FRP sheet wrapping: Experimental study", Struct. Eng. Mech., 72(6), 723-736. https://doi.org/10.12989/sem.2019.72.6.723.
  18. Marthong, C., Deb, S. and Dutta A. (2018), "Effect of loading rates on the behavior of epoxy-repaired RC beam-column connections", Europ. J. Environ. Civil Eng., 22(10), 1212-1237. https://doi.org/10.1080/19648189.2016.1248790.
  19. Park, R. and Ang, A.H.S. (1985), "Mechanistic seismic damage model for reinforced concrete", Struct. Eng., ASCE, 111(4), 722-739. https://doi.org/10.1061/(ASCE)07339445(1985)111:4(722).
  20. Pohoryles, D.A., Melo, J., Rossetto, T. and Varum, H. (2019), "Seismic retrofit schemes with FRP for deficient RC beam-column joints: State-of-the-art review." J. Compos. Construct., 23(4), https://doi.org/10.1061/(ASCE)CC.1943-5614.0000950.
  21. SikaWrap® FX-50C (2017), "Carbon fibre string for structural strengthening and connection, and anchoring of SikaWrap® strengthening systems", Product Data Sheet, Sika, May.
  22. SikaWrap® FX Fibre Connector (2013), "Method statement. Tamplate for local adaption", Annika Baier, Sika Services AG, Version 1, 24.09.2013.
  23. Tsonos, A.G. (2002), "Seismic repair of reinforced concrete beam-column subassemblages of modern structures by epoxy injection technique", Struct. Eng. Mech., 14(5), 543-563. https://doi.org/10.12989/sem.2002.14.5.543
  24. Tsonos, A.G. (2007), "Effectiveness of CFRP-jackets in postearthquake and pre-earthquake retrofitting of beam-column subassemblages", Struct. Eng. Mech., 27(4), 393-408. https://doi.org/10.12989/sem.2007.27.4.393
  25. Tsonos, A.G. (2008), "Ultra-high-performance fiber reinforced concrete: An innovative solution for strengthening old RC structures and for improving the FRP strengthening method", WIT Transactions Eng. Sci., 64, 273-284, https://doi:10.2495/MC090261.
  26. Tsonos, A.G. (2019), "A Model for the evaluation of the beam-column joint ultimate strength - a more simplified version", Earthq. Struct., 16(2), 141-148, https://doi:10.12989/eas.2019.16.2.141
  27. Tsonos, A.G. and Papanikolaou, K.V. (2003), "Post-earthquake repair and strengthening of reinforced concrete beam-column connections (theoretical & experimental investigation)", Bull. New Zealand Soc. Earthq. Eng., 36(2), 73-93, https://doi:10.5459/bnzsee.36.2.73-93.
  28. Yurdakul, O. and Avsar, O. (2016), "Strengthening of substandard reinforced concrete beam-column joints by external post-tension rods", Eng. Struct., 107, 9-22. https://doi.org/10.1016/j.engstruct.2015.11.004.

Cited by

  1. Effectiveness of the Novel Rehabilitation Method of Seismically Damaged RC Joints Using C-FRP Ropes and Comparison with Widely Applied Method Using C-FRP Sheets-Experimental Investigation vol.13, pp.11, 2021, https://doi.org/10.3390/su13116454
  2. Application of X-Shaped CFRP Ropes for Structural Upgrading of Reinforced Concrete Beam-Column Joints under Cyclic Loading-Experimental Study vol.9, pp.7, 2021, https://doi.org/10.3390/fib9070042
  3. Behaviour of repaired RC beam-column joints using welded wire mesh and jacketed with polymer modified mortar vol.21, pp.1, 2021, https://doi.org/10.12989/eas.2021.21.1.079