Structural Engineering and Mechanics

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Analytical and numerical studies on hollow core slabs strengthened with hybrid FRP and overlay techniques

  • Kankeri, Pradeep (Department of Civil Engineering, Vardhaman College of Engineering) ;
  • Prakash, S. Suriya (Department of Civil Engineering, Indian Institute of Technology) ;
  • Pachalla, Sameer Kumar Sarma (Department of Civil Engineering, Mahindra Ecole Centrale)
  • Received : 2017.04.01
  • Accepted : 2018.01.03
  • Published : 2018.03.10
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Abstract

The objective of this study is to understand the behaviour of hollow core slabs strengthened with FRP and hybrid techniques through numerical and analytical studies. Different strengthening techniques considered in this study are (i) External Bonding (EB) of Carbon Fiber Reinforced Polymer (CFRP) laminates, (ii) Near Surface Mounting (NSM) of CFRP laminates, (iii) Bonded Overlay (BO) using concrete layer, and (iv) hybrid strengthening which is a combination of bonded overlay and NSM or EB. In the numerical studies, three-dimensional Finite Element (FE) models of hollow core slabs were developed considering material and geometrical nonlinearities, and a phased nonlinear analysis was carried out. The analytical calculations were carried out using Response-2000 program which is based on Modified Compression Field Theory (MCFT). Both the numerical and analytical models predicted the behaviour in agreement with experimental results. Parametric studies indicated that increase in the bonded overlay thickness increases the peak load capacity without reducing the displacement ductility. The increase in FRP strengthening ratio increased the capacity but reduced the displacement ductility. The hybrid strengthening technique was found to increase the capacity of the hollow core slabs by more than 100% without compromise in ductility when compared to their individual strengthening schemes.

Keywords

References

  1. ACI 318 (2011), Building Code Requirements for Structural Concrete and Commentary, American Concrete Institute, Farmington Hills, MI, U.S.A.
  2. ACI 440 (2004), Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Existing Structures, American Concrete Institute, Farmington Hills, MI, U.S.A.
  3. Barbosa, A.F. and Ribeiro, G.O. (1998), Analysis of Reinforced Concrete Structures Using Ansys Nonlinear Concrete Model, COMPUTATIONAL MECHANICS, New Trends and Applications S. Idelsohn, E. Onate and E. Dvorkin (Eds.) (C) CIMNE, Barcelona, Spain, 1-7.
  4. Becker, R.J. and Buettner, D.R. (1985), "Shear tests of extruded hollow-core slabs", PCI J., 30(2), 40-54. https://doi.org/10.15554/pcij.03011985.40.54
  5. Bentz, E.C., Vecchio, F.J. and Collins, M.P. (2006), "Simplified modified compression field theory for calculating shear strength of reinforced concrete elements", ACI Struct. J., 103(4), 614-624.
  6. Brunesi, E. and Nascimbene, R. (2015), "Numerical web-shear strength assessment of precast prestressed hollow core slab units", Eng. Struct., 102, 13-30. https://doi.org/10.1016/j.engstruct.2015.08.013
  7. Brunesi, E., Bolognini, D. and Nascimbene, R. (2014), "Evaluation of the shear capacity of precast-prestressed hollow core slabs: Numerical and experimental comparisons", Mater. Struct., 48(5), 1503-1521. https://doi.org/10.1617/s11527-014-0250-6
  8. Devalapura, R.K. and Tadraos, M.K. (1992), "Stress-strain modeling of 270ksi low-relaxation prestressing strands", PCI J., 37(2), 100-105. https://doi.org/10.15554/pcij.03011992.100.106
  9. El-Hacha, R. and Rizkalla, S.H. (2004), "Near-surface-mounted fiber-reinforced polymer reinforcements for flexural strengthening of concrete structures", ACI Struct. J., 101(5), 717-726.
  10. Elgabbas, F., El-Ghandour, A.A., Abdelrahman, A.A. and El-Dieb, A.S. (2010), "Different cfrp strengthening techniques for prestressed hollow core concrete slabs: Experimental study and analytical investigation", Compos. Struct., 92(2), 401-411. https://doi.org/10.1016/j.compstruct.2009.08.015
  11. Gan, Y. (2000), "Bond stress and slip modelling in nonlinear finite element analysis of reinforced concrete structures", M.Sc. Dissertation, University of Toronto, Toronto, Canada.
  12. Ghasemi, S. Maghsoudi, A.A. Bengar, H.A. and Ronagh, H.R. (2015) "Flexural strengthening of continuous unbonded posttensioned concrete beams with end-anchored CFRP laminates", Struct. Eng. Mech., 53(6), 1083-1104. https://doi.org/10.12989/sem.2015.53.6.1083
  13. Hawileh, R.A. (2012), "Nonlinear finite element modeling of RC beams strengthened with NSM FRP rods", Constr. Build. Mater., 27(1), 461-471. https://doi.org/10.1016/j.conbuildmat.2011.07.018
  14. Hawkins, N.M. and Ghosh, S.K. (2006), "Shear strength of hollow-core slabs", PCI J., 51(1), 110-114. https://doi.org/10.15554/pcij.09012006.110.130
  15. Hegger, J., Roggendorf, T. and Teworte, F. (2010), "FE analyses of shear-loaded hollow-core slabs on different supports", Mag. Concrete Res., 62(8), 531-541. https://doi.org/10.1680/macr.2010.62.8.531
  16. Jendele, J. and Cervenka, J. (2006), "Finite element modelling of reinforcement with bond", Compos. Struct., 84(28), 1780-1791. https://doi.org/10.1016/j.compstruc.2006.04.010
  17. Kankeri, P. and Prakash, S.S. (2016), "Efficient hybrid strengthening for precast hollow core slabs at low and high shear span to depth ratios", Compos. Struct., 170, 202-214.
  18. Kankeri, P. and Prakash, S.S. (2016), "Experimental evaluation of bonded overlay and NSM GFRP bar strengthening on flexural behavior of precast prestressed hollow core slabs", Eng. Struct., 120, 49-57. https://doi.org/10.1016/j.engstruct.2016.04.033
  19. Lam, D., Elliott, K.S. and Nethercot, D.A. (2000), "Parametric study on composite steel beams with precast concrete hollow core floor slabs", J. Constr. Steel Res., 54(2), 283-304. https://doi.org/10.1016/S0143-974X(99)00049-8
  20. Pachalla, S.K.S. and Prakash, S.S. (2017), "Experimental evaluation on effect of openings on behavior of prestressed precast hollow-core slabs", ACI Struct. J., 114(2), 12.
  21. Pachalla, S.K.S. and Prakash, S.S. (2017), "Load resistance and failure modes of GFRP composite strengthened hollow core slabs with openings", Mater. Struct., 50(3), 1-14. https://doi.org/10.1617/s11527-016-0885-6
  22. Pachalla, S.K.S. and Prakash, S.S. (2018), "Load resistance and failure modes of openings-a finite element study", PCI J., Accepted.
  23. Pachalla, S.K.S. and Prakash, S.S. (2017), "Efficient near surface mounting CFRP strengthening of pretensioned hollow core slabs with opening-an experimental study", Compos. Struct., 162(2), 28-38. https://doi.org/10.1016/j.compstruct.2016.11.072
  24. Pajari, B.M. (1998), "Shear resistance of PHC slabs supported on beams. II: Analysis", J. Struct. Eng., 124(9), 1062-1073. https://doi.org/10.1061/(ASCE)0733-9445(1998)124:9(1062)
  25. Palmer, K.D. and Schultz, A.E. (2012), "Experimental investigation of the web-shear strength of deep hollow-core units", PCI J., 56, 83-104.
  26. Panda, K.C., Bhattacharyya, S.K. and Barai, S.V. (2013), "Shear strengthening effect by bonded GFRP strips and transverse steel on RC T-beams", Struct. Eng. Mech., 47(1), 75-98. https://doi.org/10.12989/sem.2013.47.1.075
  27. Sakar, G., Hawileh, R.A., Naser, M.Z., Abdalla, J.A. and Tanarslan, M. (2014), "Nonlinear behavior of shear deficient RC beams strengthened with near surface mounted glass fiber reinforcement under cyclic loading", Mater. Des., 61, 16-25. https://doi.org/10.1016/j.matdes.2014.04.064
  28. Saribiyik, A. and Caglar, N. (2016), "Flexural strengthening of RC beams with low-strength concrete using GFRP and CFRP", Struct. Eng. Mech., 58(5), 825-845. https://doi.org/10.12989/sem.2016.58.5.825
  29. Sharaky, I. A., Torres, L., Comas, J. and Barris, C. (2014), "Flexural response of reinforced concrete (RC) beams strengthened with near surface mounted (NSM) fibre reinforced polymer (FRP) bars", Compos. Struct., 109, 8-22. https://doi.org/10.1016/j.compstruct.2013.10.051
  30. Vecchio, F.J. and Collins, M.P. (1986), "Predicting the response of reinforced concrete beams subjected to shear using modified compression field theory", ACI Struct. J., 85(3), 258-268.
  31. Vecchio, F.J. and Collins, M.P. (1986), "The modified compression-field theory for reinforced concrete element subjected to shear", ACI Struct. J., 83(2), 219-231.
  32. Walraven, J.C. and Mercx, W.P.M. (1983), "Bearing capacity of prestressed hollow core slabs", Heron, 28, 1-46.
  33. Wang, X. (2007) "Study on the shear behaviour of prestressed hollow core slabs by nonlinear finite element modelling", Ph.D. Dissertation, University of Windsor, Windsor, Canada.
  34. Yang, L. (1994), "Design of prestressed hollow core slabs with reference to web shear failure", J. Struct. Eng., 120(9), 2675-2696. https://doi.org/10.1061/(ASCE)0733-9445(1994)120:9(2675)