Earthquakes and Structures

Techno-Press (테크노프레스)
권호 표지
DOI QR코드

DOI QR Code

Improvement of the cyclic response of RC columns with inadequate lap splices-Experimental and analytical investigation

  • Kalogeropoulos, George I. (Department of Civil Engineering, Aristotle University of Thessaloniki) ;
  • Tsonos, Alexander-Dimitrios G. (Department of Civil Engineering, Aristotle University of Thessaloniki)
  • Received : 2019.01.08
  • Accepted : 2019.01.26
  • Published : 2019.03.25
⟨ Previous Next ⟩

Abstract

The overall seismic performance of existing pre 1960-70s reinforced concrete (RC) structures is significantly affected by the inadequate length of columns' lap-spliced reinforcement. Due to this crucial structural deficiency, the cyclic response is dominated by premature bond - slip failure, strength and stiffness degradation, poor energy dissipation capacity and low ductility. Recent earthquakes worldwide highlighted the importance of improving the load transfer mechanism between lap-spliced bars, while it was clearly demonstrated that the failure of lap splices may result in a devastating effect on structural integrity. Extensive experimental and analytical research was carried out herein, to evaluate the effectiveness and reliability of strengthening techniques applied to RC columns with lap-spliced reinforcement and also accurately predict the columns' response during an earthquake. Ten large scale cantilever column subassemblages, representative of columns found in existing pre 1970s RC structures, were constructed and strengthened by steel or RC jacketing. The enhanced specimens were imposed to earthquake-type loading and their lateral response was evaluated with respect to the hysteresis of two original and two control subassemblages. The main variables examined were the lap splice length, the steel jacket width and the amount of additional confinement offered by the jackets. Moreover, an analytical formulation proposed by Tsonos (2007a, 2019) was modified appropriately and applied to the lap splice region, to calculate shear stress developed in the concrete and predict if yielding of reinforcement is achieved. The accuracy of the analytical method was checked against experimental results from both the literature and the experimental work included herein.

Keywords

References

  1. Aboutaha, R.S., Engelhardt, M.D., Jirsa, J.O. and Kreger, E.M. (1996), "Retrofit of concrete columns with inadequate lap splices by the use of rectangular steel jackets", Earthq. Spectra, 12(4), 693-614. https://doi.org/10.1193/1.1585906
  2. Aboutaha, R.S., Engelhardt, M.D., Jirsa, J.O. and Kreger, M.E. (1999), "Rehabilitation of shear critical concrete columns by use of rectangular steel jackets", ACI Struct. J., 96(1), 68-78.
  3. Chai, H.Y., Priestley, M.J.N. and Seible, F. (1991), "Seismic retrofit of circular bridge columns for enhanced flexural performance", ACI Struct. J., 88(5), 572-584.
  4. Chalioris, C., Favatta, M. and Karayannis, C. (2008), "A new method for the seismic rehabilitation of old exterior reinforced concrete beam-column joints", Proceedings of the 7th European Conference on Struct. Dyn., Southampton, UK E245.
  5. Choi, E., Chung, Y.S., Park, K. and Jeon, J.S. (2013), "Effect of steel wrapping jackets on the bond strength of concrete and the lateral performance of circular rc columns", Eng. Struct., 48, 43-54. https://doi.org/10.1016/j.engstruct.2012.08.026
  6. CSRTC (2008), New Code of Steel Reinforcement Technology for Concrete, Athens, Greece.
  7. Daudey, X. and Filiatrault, A. (2000), "Seismic evaluation and retrofit with steel jackets of reinforced concrete bridge piers detailed with lap-splices", Can. J. Civil Eng., 27(1), 1-16. https://doi.org/10.1139/l99-029
  8. Durrani, A.J. and Wight, JK. (1987), "Earthquake resistance of reinforced concrete interior connections including a floor slab", ACI J. Proc., 84(84-S42), 400-406.
  9. Ehsani, M. (2010), "FRP super laminates", ACI Concrete Int., 32(3), 49-53.
  10. Ehsani, M.R. and Wight, J.K. (1985), "Effect of transverse and slab on behavior of reinforced concrete beam-to-column connections", ACI J. Proc., 82(17), 188-195.
  11. Ehsani, M.R. and Wight, J.K. (1985), "Exterior reinforced concrete beam-to-column connections subjected to earthquake - type loading", ACI J. Proc., 82(4), 492-499.
  12. El Gawady, M., Endeshaw, M., McLean, D. and Sack, R. (2010), "Retrofitting of rectangular columns with deficient lap splices", J. Compos. Constr., 14(1), 22-35. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000047
  13. EN 1992-1-1 Eurocode 2 (2004), Design of Concrete Structures. Part 1-1: General Rules and Rules for Buildings, 224.
  14. EN 1998-1 Eurocode 8 (2004), Design of Structures for Earthquake Resistance. Part 1: General Rules, Seismic Actions and Rules for Buildings, Stage 51, 229.
  15. Greek Code for Interventions (2017), Earthquake Planning and Protection Organisation, Athens.
  16. Hackman, L., Farell, M. and Dunhan, O. (1992), "Slurry infiltrated mat concrete (SIMCON)", Concrete Int., 14(12), 53-56.
  17. Hakuto, S., Park, R. and Tanaka, H. (2000), "Seismic load tests on interior and exterior beam-column joints with substandard reinforcing details", ACI Struct. J., 97(1), 11-25.
  18. Hamilton, H.C., Pardoen, C.G., Navalpakkam, S. and Kanzanjy, P.R. (2004), "Reinforced concrete bridge column performance enhancement through shotcrete jacketing", ACI Struct. J., 101(3), 332-340.
  19. Henager, C.H. (1997), "Steel fibrous ductile concrete joints for seismic-resistant structures. Reinforced concrete structures in seismic zones", ACI Special Publications SP-53, American Concrete Institute, Detroit, USA.
  20. Julio, N.B.S.E. and Branco, A.B.F. (2008), "Reinforced concrete jacketing-interface influence on cyclic loading response", Struct. J., 105(4), 471-477.
  21. Kalogeropoulos, G. and Tsonos, A.D. (2014), "Effectiveness of r/c jacketing of substandard r/c columns with short lap splices", Struct. Monit. Maint., 1(3), 273-292. https://doi.org/10.12989/SMM.2014.1.3.273
  22. Kalogeropoulos, G., Tsonos, A.D., Konstandinidis, D. and Tsetines, S. (2016), "Pre-earthquake and post-earthquake retrofitting of poorly detailed exterior RC beam-to-column joints", Eng. Struct., 109, 1-15. https://doi.org/10.1016/j.engstruct.2015.11.009
  23. Karayannis, C., Chalioris, C. and Sirkelis, G. (2008), "Local retrofit of exterior beam-column joints using thin RC jackets - an experimental study", Earthq. Eng. Struct. Dyn., 37, 727-746. https://doi.org/10.1002/eqe.783
  24. Karayannis, C.G. and Sirkelis, G.M. (2008), "Strengthening and rehabilitation of rc beam-column joints using carbon-FRP jacketing and epoxy resin injection", Earthq. Eng. Struct. Dyn., 37(5), 769-790. https://doi.org/10.1002/eqe.785
  25. Lynn, A.C., Moehle, J.P., Mahin, S.A. and Holmes, W.T. (1996), "Seismic evaluation of existing reinforced concrete building columns", Earthq. Spectra, 12(4), 715-739. https://doi.org/10.1193/1.1585907
  26. Melek, M. and Wallace, J.W. (2004), "Cyclic behavior of columns with short lap splices", ACI Struct. J., 101(6), 802-811.
  27. Pampanin, S., Bolognini, D. and Pavese, A. (2007), "Performancebased seismic retrofit strategy for existing reinforced concrete frame systems using fiber-reinforced polymer composites", J. Compos. Constr., 11(2), 211-226. https://doi.org/10.1061/(ASCE)1090-0268(2007)11:2(211)
  28. Paulay, T. (1982), "Lapped splices in earthquake-resisting columns", ACI Struct. J., 79(6), 458-469.
  29. Paulay, T. and Priestley, M.J.N. (1992), Seismic Design of Reinforced Concrete and Masonry Vuildings, John Wiley and Sons, New York, NY, USA.
  30. Pavese, A., Bolognini, D. and Peloso, S. (2004), "FRP seismic retrofit of RC square hollow section bridge piers", J. Earthq. Eng., 8(1), 225-250. https://doi.org/10.1080/13632460409350526
  31. Rodriguez, M. and Park, R. (1994), "Seismic load tests on reinforced concrete columns strengthened by jacketing", ACI Struct. J., 91(2), 150-159.
  32. Saadatmanesh, H., Ehsani, M.R. and Jin, L. (1997), "Repair of earthquake-damaged RC columns with FRP wraps", ACI Struct. J., 94(2), 206-214.
  33. Tsonos, A. (2007b), "Steel fiber reinforced concrete of highstrength for the construction of jackets for earthquakestrengthening of buildings without the use of conventional reinforcement", Patent No 1005657 awarded by the Greek Industrial Property Organization (OBI).
  34. Tsonos, A.D. (2010), "Performance enhancement of R/C building columns and beam-column joints through shotcrete jacketing", Eng. Struct., 32(3), 726-740. https://doi.org/10.1016/j.engstruct.2009.12.001
  35. Tsonos, A.D. (2014), "An innovative solution for strengthening of old R/C structures and for improving the FRP strengthening method", Struct. Monit. Maint., 1(3), 323-338. https://doi.org/10.12989/SMM.2014.1.3.323
  36. Tsonos, A.D. (2019), "Model for the evaluation of the beamcolumn joint ultimate strength-a more simplified version", Earthq. Struct., 16(2), 141-148. https://doi.org/10.12989/EAS.2019.16.2.141
  37. Tsonos, A.D., Kalogeropoulos, G., Iakovidis, P. and Konstantinidis, D. (2017), "Seismic retrofitting of pre-1970 RC bridge columns using innovative jackets", Int. J. Struct. Eng., 8(2), 133-147. https://doi.org/10.1504/IJSTRUCTE.2017.084631
  38. Tsonos, A.G. (2007a), "Cyclic load behaviour of reinforced concrete beam-column subassemblages of modern structures", ACI Struct. J., 194(4), 468-478.
  39. Tsonos, A.G. (2008), "Effectiveness of CFRP-jackets and r/c-jackets in post-earthquake and pre-earthquake retrofitting of beam-column subassemblages", Eng. Struct., 30(3), 777-793. https://doi.org/10.1016/j.engstruct.2007.05.008
  40. Yeh, Y. and Mo, Y. (2005), "Shear retrofit of hollow bridge piers with carbon fiber-reinforced polymer sheets", J. Compos. Constr., 9(4), 327-336. https://doi.org/10.1061/(ASCE)1090-0268(2005)9:4(327)

Cited by

  1. Cyclic Performance of RC Columns with Inadequate Lap Splices Strengthened with CFRP Jackets vol.8, pp.6, 2019, https://doi.org/10.3390/fib8060039
  2. Seismic Performance Enhancement of RC Columns Using Thin High-Strength RC Jackets and CFRP Jackets vol.9, pp.5, 2019, https://doi.org/10.3390/fib9050029
  3. 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
  4. Application of X-Shaped CFRP Ropes for Structural Upgrading of Reinforced Concrete Beam-Column Joints under Cyclic Loading-Experimental Study vol.9, pp.7, 2019, https://doi.org/10.3390/fib9070042