Effects of joint aspect ratio on required transverse reinforcement of exterior joints subjected to cyclic loading

  • Chun, Sung Chul (Division of Architecture and Urban Design, Incheon National University)
  • Received : 2014.03.18
  • Accepted : 2014.05.01
  • Published : 2014.11.25


This paper presents an analytical model for determining the transverse reinforcement required for reinforced concrete exterior beam-column joints subjected to reversed cyclic loading. Although the joint aspect ratio can affect joint shear strength, current design codes do not consider its effects in calculating joint shear strength and the necessary amount of transverse reinforcement. This study re-evaluated previous exterior beam-column joint tests collected from 11 references and showed that the joint shear strength decreases as the joint aspect ratio increases. An analytical model was developed, to quantify the transverse reinforcement required to secure safe load flows in exterior beam-column joints. Comparisons with a database of exterior beam-column joint tests from published literature validated the model. The required sectional ratios of horizontal transverse reinforcement calculated by the proposed model were compared with those specified in ACI 352R-02. More transverse reinforcement is required as the joint aspect ratio increases, or as the ratio of vertical reinforcement decreases; however, ACI 352R-02 specifies a constant transverse reinforcement, regardless of the joint aspect ratio. This reevaluation of test data and the results of the analytical model demonstrate a need for new criteria that take the effects of joint aspect ratio into account in exterior joint design.


exterior beam-column joints;joint aspect ratio;joint shear strength;transverse reinforcement;strut-and-tie model


Supported by : Korea Institute of Energy Technology Evaluation and Planning (KETEP), National Research Foundation of Korea (NRF)


  1. Chun, S.C. and Shin, Y.S. (2014), "Cyclic testing of exterior beam-column joints with varying joint aspect ratio", ACI Struct. J., 111((in press)).
  2. ACI-ASCE Committee 352 (2002), "Recommendations for design of beam-column connections in monolithic reinforced concrete structures (ACI 352R-02)", American Concrete Institute, Farmington Hills, Mich., 37.
  3. ACI318 (2011), "Building Code Requirements for Structural Concrete (ACI 318-11) and Commentary ", American Concrete Institute, Farmington Hills, Mich., 503.
  4. Brown, M.D. and Bayrak, O. (2006), "Minimum transverse reinforcement for bottle-shaped struts", ACI Struct. J., 103(6), 813-821.
  5. CEB-FIP (1999), FIP Recommendations; Practical Design of Structural Concrete.
  6. Chun, S.C., Ha, T., Hong, S.G. and Oh, B. (2007), "discussion on "Minimum transverse reinforcement for bottle-shaped struts", ACI Struct. J., 104(5), 643-644.
  7. Ehsani, M.R. and Alameddine, F. (1991), "Design recommendations for type 2 high-strength reinforced concrete connections", ACI Struct. J., 88(3), 277-291.
  8. Ehsani, M.R., Moussa, A.E. and Vallenilla, C.R. (1987), "Comparison of inelastic behavior of reinforced ordinary- and high-strength concrete frames", ACI Struct. J., 84(2), 161-169.
  9. Ehsani, M.R. and Wight, J.K. (1985), "Exterior reinforced concrete beam-to-column connections subjected to earthquake-type loading", ACI Struct. J., 82(4), 492-499.
  10. Eurocode 8 (2004), "Design of structures for earthquake resistance Part: General rules, seismic actions and rules for buildings", 229.
  11. Fardis, M., Carvalho, E., Elnashai, A., Faccioli, E. and Pinto, P. (2005), Eurocode 8: Design of Structures for Earthquake Resistance, Thomas Telford.
  12. Fujii, S. and Morita, S. (1991), "Comparison between Interior and Exterior RC Beam-Column Joint Behavior", Design of Beam-Column Joints for Seismic Resistance, SP-123, J.O. Jirsa, Ed., American Concrete Institute, Farmington Hills, Mich., 145-166.
  13. Hong, S.G., Chun, S.C., Lee, S.H. and Oh, B. (2007), "Strut-and-tie model for development of headed bars in exterior Beam-Column Joint", ACI Struc. J., 104(5), 590-600.
  14. Hwang, S.J. and Lee, H.J. (1999), "Analytical model for predicting shear strength of exterior reinforced concrete beam-column joints for seismic resistance", ACI Strut. J., 96(5), 846-857.
  15. Hwang, S.J., Lee, H.J., Liao, T.F., Wang, K.C. and Tsai, H.H. (2005), "Role of hoops on shear strength of reinforced concrete beam-column joints", ACI Struct. J., 102(3), 445-453.
  16. Jennewein and Schafer (1992), "Standardisierte nachweise von haufigen D-bereichen (in German)", DAfStb, HeftBerlin, 430.
  17. Lu, X., Urukap, T.H., Li, S. and Lin, F. (2012), "Seismic behavior of interior RC beam-column joints with additional bars under cyclic loading", Earthq. Struct., 3(1), 37-57.
  18. Kaku, T. and Asakusa, H. (1991), "Ductility estimation of exterior beam-column subassemblages in reinforced-concrete frames", Design of Beam-Column Joints for Seismic Resistance, SP-123, J. O. Jirsa, ed., American Concrete Institute, Farmington Hills, Mich., 167-185.
  19. LaFave, J. M. and Kim, J. (2011), "Joint shear behavior prediction for RC beam-column connections", Int. J. Concrete Struct. Mater., 5(1), 57-64.
  20. Lee, D.L.N., Wight, J.K. and Hanson, R.D. (1977), "RC beam-column joints under large load reversals", J. Struct. Div., Proceedings of the ASCE, 103(ST12), 2337-2350.
  21. Sahoo, D.K., Singh, B. and Bhargava, P. (2011), "Minimum reinforcement for preventing splitting failure in bottle-shaped struts", ACI Struct. J., 108(2), 206-216.
  22. Schafer (1996), "Strut-and-Tie Models for Design of Structural Concrete", Notes of Workshop National Cheng Kung University, Tainan, Taiwan, 140.
  23. Tsonos, A.G. (2007), "Cyclic load behavior of reinforced concrete beam-column sub-assemblages of modern structures", ACI Struct. J., 104(4), 468-478.
  24. Uzummeri, S.M. (1977), "Strength and ductility of cast-in-place beam-column joints", Reinforced Concrete Structures in Seismic Zones, SP-53, American Concrete Institute, Farmington Hills, 293-350.
  25. Wong, H.F. and Kuang, J.S. (2008), "Effects of beam-column depth ratio on joint seismic behavior", Proceedings of the Institute of Civil Engineers, 161(sb2), 91-101.
  26. Xing, G.H., Wu, T., Niu, D.T. and Liu, X. (2013), "Seismic behavior of reinforced concrete interior beam-column joints with beams of different depths", Earthq. Struct., 4(4), 429-449.