Computers and Concrete

Techno-Press (테크노프레스)
권호 표지
DOI QR코드

DOI QR Code

Stud reinforcement in beam-column joints under seismic loads

  • Received : 2013.12.13
  • Accepted : 2016.06.21
  • Published : 2016.09.25
⟨ Previous Next ⟩

Abstract

Current codes recommend large amounts of shear reinforcement for reinforced concrete beam-column joints that causes significant bar congestion. Increase in congestion of shear reinforcement in joint core (connection zone), leads to increase accomplishment problems. The congestion may also lead to diameter limitations on the beam bars relative to the joint dimensions. Using double headed studs instead of conventional closed hoops in reinforced concrete beam-column joints reduces congestion and ensures easier assembly of the reinforcing cage. The purpose of this research is evaluating the efficiency of the proposed reinforcement. In this way, 10 groups of exterior beam-column joints are modeled. Each group includes 7 specimens by different reinforcing details in their joint core. All specimens are modeled by using of ABAQUS and analyzed subjected to cyclic loading. After verification of analytical modeling with an experimental specimen, 3D nonlinear specimens are modeled and analyzed. Then, the effect of amount and arrangement of headed studs on ductility, performance, ultimate strength and energy absorption has been studied. Based on the results, all joints reinforced with double headed studs represent better performance compared with the joints without shear transverse reinforcement in joints core. The behavior of the former is close to joints reinforced with closed hoops and cross ties according to the seismic design codes. By adjusting the arrangement of double-headed studs, the decrease in ductility, performance, ultimate moment resistant and energy absorption reduce to 2.61%, 0.90%, 0.90% and 1.66% respectively compared with the joints reinforced by closed hoops on the average. Since the use of headed studs reduces accomplishment problems, these amounts are negligible. Therefore, use of double-headed studs has proved to be a viable option for reinforcing exterior beam-column joints.

Keywords

References

  1. ABAQUS (2008), User's Manual V.6.9.1.
  2. ACI Committee 318 (1995), "Building code requirements for structural concrete (ACI318-95) and Commentary (318R-95)", American Concrete Institute, Farmington Hills, MI, 369 pages.
  3. ACI Committee 318 (2005), "Building code requirements for reinforced concrete (ACI318-05) and commentary (ACI 318R-05)", American Concrete Institute, Farmington Hills, MI.
  4. ACI Committee 318 (2008), "Building code requirements for structural concrete (ACI 318-08) and commentary", American Concrete Institute, Farmington Hills, Michigan, 465 pp.
  5. Birkle, G., Ghali, A., and Schafer, K. (2002), "Double-headed studs improve corbel reinforcement", Concrete Int., 24(9), 77-84.
  6. CSA Standard A23.3-04 (2004), "Design of concrete structures", Canadian Standards Association, Rexdale, Ontario, Canada, 240 pages.
  7. Dilger, W.H. and Ghali, A. (1981), "Shear reinforcement for concrete slabs", J. Struct. Div., 107(12), 2403-2420.
  8. Gayed, R.B. and Ghali, A. (2004), "Double-head studs as shear reinforcement in concrete I-beams", ACI Struct. J., 101(4), 550-557.
  9. Ghali, A. and Dilger, W.H. (1998), "Anchoring with double-head studs", Concrete Int., 20(11), 21-24.
  10. Hanson N.W. and Conner H.W. (2008), "Seismic resistance of reinforced concrete beam-column joints", The university of California, Pub. Portland Cement Association, Research and Development Laboratories.
  11. Hwang, S.J. and Lee, H.J. (1999), "Analytical model for predicting shear strengths of exterior reinforced concrete beam-column joints for seismic resistance", ACI Struct. J., 96(5), 846-857.
  12. Hwang, S.J. and Lee, H.J. (2002), "Strength prediction for discontinuity regions by softened Strut-and-Tie model", J. Struct. Eng., 128(12), 1519-1526. https://doi.org/10.1061/(ASCE)0733-9445(2002)128:12(1519)
  13. Ibrahim, H.H.A. (2011), "Stud reinforcement in beam-column joints under seismic loads", Ph.D. thesis, Department of Civil Engineering Calgary, Alberta, 358 pages.
  14. Khalifa, H. and Alnaji, E.M. (2008), "Investigating shear capacity of RC beam-column joints using artificial intelligence techniques", Ph.D. thesis, University of Nevada, Las Vegas, 126 pages.
  15. Li, B. and Tran, T.N. (2009), "Seismic behavior of reinforced concrete beam-column joints with vertically distributed reinforcement", ACI Struct. J., 106(6), 790-799.
  16. Mahini, S.S. and Ronagh, H.R. (2010), "Strength and ductility of FRP web-bonded RC beams for the assessment of retrofitted beam-column joints", Compos. Struct. J., 92(6),1325-1332. https://doi.org/10.1016/j.compstruct.2009.09.006
  17. Mobeen, S.S., Elwi, A.E. and Ghali, A. (2005), "Double-headed studs in shear walls", Concrete Int., 27(3), 59-63.
  18. Mostofinezhad, D. and Sobhani, J. (2003), "Behavioral study and classification of exterior reinforced concrete beam-column joints under ultimate load", J. Fac. Eng. (University of Tehran), 37(80), 295-310.
  19. Nilson, I.H.E. (1973), "Reinforced concrete corner and joints subjected to bending moment", National Swedish for Building Research, 249 pages.
  20. Paulay, T. and Priestley, M.J.N. (1992), "Seismic design of reinforced concrete and masonry buildings", John Wiley & Sons, 768 pages.
  21. Sangjoon, P. and Khalid, M.M. (2012), "Parameters for shear strength prediction of exterior beam-column joints without transverse reinforcement", Eng. Struct. J., 36, 198-209. https://doi.org/10.1016/j.engstruct.2011.11.017
  22. Shirazi, H. (2011), "Cyclic behavior of reinforced concrete external beam-column joints with consideration detailing arrangement of reinforcement bars and type of used concrete in joint core", Ph.D. thesis, Ferdowsi University, Mashhad, Iran, 158 pages.
  23. Thompson, M.K., Jirsa, J.O., Breen, J.E. and Klingner, R.E. (2002), "Anchorage behavior of headed reinforcement: literature review", Ph.D. thesis, Department of Civil Engineering, Texas University, Austin, 116 pages.
  24. Tjhin, T.N. and Kuchma, D.A. (2002), "Computer-based tools for design by Strut-and Tie method: advances and challenges", ACI Struct. J., 99(5), 586-594.
  25. Ueda, I.L. and Hawkins N.M. (1986), "Beam bar anchorage in exterior column-beam connections", ACI J., 927-936.
  26. Wong, H.F. (2005), "Shear strength and seismic performance of non-seismically designed reinforced concrete beam-column joints", Ph.D. thesis, Hong Kong University of Science and Technology (Hong Kong), 341 pages.
  27. Youakim, S.A. (2002), "Double headed studs as cross ties in concrete columns: earthquake resistance", Ph.D. thesis, Department of Civil Engineering, University of Calgary, Canada.
  28. Youakim, S.A. and Ghali, A. (2002), "Ductility of concrete columns with double head studs", ACI Struct. J., 99(4), 480-487.
  29. Youakim, S.A. and Ghali, A. (2003), "Behavior of concrete columns with double head studs under earthquake loading: parametric study", ACI Struct. J., 100(6), 795-803.