Computers and Concrete

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Maximum axial load level and minimum confinement for limited ductility design of high-strength concrete columns

  • Lam, J.Y.K. (Department of Civil Engineering, The University of Hong Kong) ;
  • Ho, J.C.M. (Department of Civil Engineering, The University of Hong Kong) ;
  • Kwan, A.K.H. (Department of Civil Engineering, The University of Hong Kong)
  • Received : 2009.01.05
  • Accepted : 2009.07.30
  • Published : 2009.10.25
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Abstract

In the design of concrete columns, it is important to provide some nominal flexural ductility even for structures not subjected to earthquake attack. Currently, the nominal flexural ductility is provided by imposing empirical deemed-to-satisfy rules, which limit the minimum size and maximum spacing of the confining reinforcement. However, these existing empirical rules have the major shortcoming that the actual level of flexural ductility provided is not consistent, being generally lower at higher concrete strength or higher axial load level. Hence, for high-strength concrete columns subjected to high axial loads, these existing rules are unsafe. Herein, the combined effects of concrete strength, axial load level, confining pressure and longitudinal steel ratio on the flexural ductility are evaluated using nonlinear moment-curvature analysis. Based on the numerical results, a new design method that provides a consistent level of nominal flexural ductility by imposing an upper limit to the axial load level or a lower limit to the confining pressure is developed. Lastly, two formulas and one design chart for direct evaluation of the maximum axial load level and minimum confining pressure are produced.

Keywords

References

  1. ACI Committee 318 (2005), Building Code Requirements for Reinforced Concrete and Commentary ACI 318M-05, Manual of Concrete Practice, American Concrete Institute, Michigan, USA, 436.
  2. Au, F.T.K and Bai, Z.Z. (2006), "Effect of axial load on flexural behaviour of cyclically loaded RC columns", Comput. Concrete, 3(4), 261-284. https://doi.org/10.12989/cac.2006.3.4.261
  3. Au, F.T.K., Bai, Z.Z. and Kwan, A.K.H. (2005), "Complete moment-curvature relationship of reinforced normaland high-strength concrete beams experiencing complex load histroy", Comput. Concrete, 2(4), 309-324. https://doi.org/10.12989/cac.2005.2.4.309
  4. Au, F.T.K. and Kwan, A.K.H. (2004), "A minimum ductility design method for non-rectangular high-strength concrete beams", Comput. Concrete, 1(2), 115-130. https://doi.org/10.12989/cac.2004.1.2.115
  5. Attard, M.M. and Setunge, S. (1996), "The stress strain relationship of confined and unconfined concrete", ACI Mater. J., 93(5), 432-442.
  6. Bayrak, O. and Sheikh, S.A. (1997), "High strength concrete columns under simulated earthquake loading", ACI Struct. J., 94(6), 708-722.
  7. Bayrak, O. and Sheikh, S.A. (1998), "Confinement reinforcement design consideration for ductile HSC columns", J. Strut. Eng-ASCE, 124(9), 999-1010. https://doi.org/10.1061/(ASCE)0733-9445(1998)124:9(999)
  8. Bechtoula, H., Sakashita, M., Kono, S. and Watanabe, F. (2005), "Seismic performance of 1/4-scale RC frames subjected to axial and cyclic reversed lateral loads", Comput. Concrete, 2(2), 147-164. https://doi.org/10.12989/cac.2005.2.2.147
  9. Buildings Department (2004), Code of Practice for Structural Use of Concrete 2004, The Government of Hong Kong Special Administrative Region, 180.
  10. Carreira, D.J. and Chu, K.H. (1986), "The moment-curvature relationship of reinforced concrete members", ACI ACE J. Proceed., 83(2), 191-198.
  11. Chung, Y.S., Park, C.K. and Lee, E.H. (2004), "Seismic performance and damage assessment of reinforced concrete bridge piers with lap-spliced longitudinal steels", Struct. Eng. Mech., 17(1), 99-112. https://doi.org/10.12989/sem.2004.17.1.099
  12. Chung, Y.S., Park, C.K. and Lee, D.H. (2006), "Seismic performance of RC bridge piers subjected to moderate earthquakes", Struct. Eng. Mech., 24(4), 429-446. https://doi.org/10.12989/sem.2006.24.4.429
  13. European Committee for Standardization (2004), Eurocode 2: Design of concrete structures: Part 1-1: General rules and rules for buildings, UK, 225.
  14. Fafitis, A. and Shah, S.P. (1985), "Prediction of ultimate behavior of confined columns subjected to large deformations" ACE J. Proceed., 82(4), 423-433.
  15. Galal, K. (2007), "Lateral force-displacement ductility relationship of non-ductile squat RC columns rehabilitated using FRP confinement", Struct. Eng. Mech., 25(1), 75-89. https://doi.org/10.12989/sem.2007.25.1.075
  16. Ho, J.C.M., Kwan, A.K.H. and Pam, H.J. (2004), "Minimum flexural ductility design of high-strength concrete beams", Mag. Concrete Res., 56(1), 13-22. https://doi.org/10.1680/macr.2004.56.1.13
  17. Ho, J.C.M., Au, F.T.K. and Kwan, A.K.H. (2005), "Effects of strain hardening of steel reinforcement on flexural strength and ductility of concrete beams", Struct. Eng. Mech., 19(2), 185-198. https://doi.org/10.12989/sem.2005.19.2.185
  18. Kim, J.H. (2005), "Ductility enhancement of reinforced concrete thin wall", Comput. Concrete, 2(2), 111-123. https://doi.org/10.12989/cac.2005.2.2.111
  19. Kim, T. and Kim, J. (2007), "Seismic performance evaluation of a RC special moment frame", Struct. Eng. Mech., 27(6), 671-682. https://doi.org/10.12989/sem.2007.27.6.671
  20. Kim, T.H., Park, J.G., Kim, Y.J. and Shin, H.M. (2008), "A computation platform for seismic performance assessment of reinforced concrete bridge piers with unbonded reinforcing or prestressing bars", Comput. Concrete, 5(2), 135-154. https://doi.org/10.12989/cac.2008.5.2.135
  21. Kwan, A.K.H., Ho, J.C.M. and Pam, H.J. (2002), "Flexural strength and ductility of reinforced concrete beams", P. I. Civil Eng-Str. B., 152(4), 361-369.
  22. Kwan, A.K.H., Au, F.T.K. and Chau, S.L. (2004), "Theoretical study on effect of confinement on flexural ductility of normal and high-strength concrete beams", Mag. Concrete Res., 56(5), 299-309. https://doi.org/10.1680/macr.2004.56.5.299
  23. Li, B., Park, R. and Tanaka, H. (1991), "Effect of confinement on the behaviour of high strength concrete columns under seismic loading", Proceedings of the 5th Pacific Conference on Earthquake Engineering, Auckland, November.
  24. Lu, X. and Zhou, Y. (2007), "An applied model for steel reinforced concrete columns", Struct. Eng. Mech., 27(6), 697-711. https://doi.org/10.12989/sem.2007.27.6.697
  25. Maghsoudi, A.A. and Bengar, H.A. (2006), "Flexural ductility of HSC members", Struct. Eng. Mech., 24(2), 195-212. https://doi.org/10.12989/sem.2006.24.2.195
  26. Mander, J.B., Priestley, M.J.N. and Park, R. (1988), "Theoretical stress-strain model for confined concrete", J. Struct. Eng-ASCE, 114(8), 1804-1825. https://doi.org/10.1061/(ASCE)0733-9445(1988)114:8(1804)
  27. Marefat, M.S., Khanmohammadi, M., Bahrani, M.K. and Goli, A. (2005), "Cyclic load testing and numerical modelling of concrete columns with substandard seismic details", Comput. Concrete, 2(5), 367-380. https://doi.org/10.12989/cac.2005.2.5.367
  28. Mendis, P.A., Kovacic, D. and Setunge, S. (2000), "Basis for the design of lateral reinforcement for high-strength concrete columns", Struct. Eng. Mech., 9(6), 589-600. https://doi.org/10.12989/sem.2000.9.6.589
  29. Ministry of Construction (2002), Code for Design of Concrete Structures GB 50010-2002, People's Republic of China, 96.
  30. Park, R. and Paulay, T. (1975), Reinforced Concrete Structures, Wiley, New York, U.S.A., 769.
  31. Razvi, S.R. and Saatcioglu, M. (1994), "Strength and deformability of confined high-strength concrete columns", ACI Struct. J., 91(6), 1-10.
  32. Rubinstein, M., Moller, O. and Giuliano, A. (2007), "Preliminary design and inelastic assessment of earthquakeresistant structural systems", Struct. Eng. Mech., 26(3), 297-313. https://doi.org/10.12989/sem.2007.26.3.297
  33. Sheikh, S.A., Shah, D.V. and Khoury, S.S. (1994), "Confinement of high-strength concrete columns", ACI Struct. J., 91(1), 100-111.
  34. Sung, Y.C., Liu, K.Y., Su, C.K., Tsai, I.C. and Chang, K.C. (2005), "A study on pushover analyses of reinforced concrete columns", Struct. Eng. Mech., 21(1), 35-52. https://doi.org/10.12989/sem.2005.21.1.035
  35. Standard Australia (2001), Australian Standard Concrete Structures AS 3600-2001, Australia, 175.
  36. Watson, S. and Park, R. (1994), "Simulated seismic load tests on reinforced concrete columns", J. Struct. Eng-ASCE, 120(6), 1825-1849. https://doi.org/10.1061/(ASCE)0733-9445(1994)120:6(1825)
  37. Wu, Y.F., Oehlers, D.J. and Griffith, M.C. (2004), "Rational definition of the flexural deformation capacity of RC column sections", Eng. Struct., 26, 641-650. https://doi.org/10.1016/j.engstruct.2004.01.001

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