Development and Calibration of an Efficiency Factor Model for Recycled Aggregate Concrete Struts

Document Type : Original Article


Department of Civil Engineering, S. V. National Institute of Technology, Surat, Gujarat, India


In the strut-and-tie (STM) method of design, the internal mechanism of flow of forces is represented by hypothetical truss in which the behavior of the beam is controlled by the strut connecting load and support points. The strength of such strut is correlated to the shear capacity of the deep beam through a factor called the strut efficiency factor. Different efficiency factor models have been recommended by various internationally accepted codes. However, none of the codes takes into account the effect of recycled aggregates in concrete. Although some codes yield conservative results, these predictions are not sensitive enough to the recycled aggregate content.  Therefore, an efficiency factor model sensitive to recycled aggregate concrete and easy to operate is much desired. In this work, published results of laboratory tests on deep beam specimens made of concrete consisting of recycled aggregates were considered for the analysis, employing a suitable strut-and-tie model. All these deep beams were originally designed by sectional or empirical method. Based on regression analysis of the outcomes of the STM analysis, an efficiency factor model has been proposed which takes into account the effect of recycled aggregates in concrete. Subsequently, scaled deep beam specimens containing recycled aggregate concrete were cast and tested in the laboratory in order to calibrate the proposed strut efficiency factor model. The yield of proposed efficiency factor model was compared with the predictions of the selected internationally accepted code provisions. It is found that the predictions of proposed efficiency factor model give consistent and comparable results.


Main Subjects

  1. Kassem, W., "Strength prediction of corbels using strut-and-tie model analysis", International Journal of Concrete Structures and Materials, Vol. 9, No. 2, (2015), 255-266.
  2. Kassem, W., "Shear strength of squat walls: A strut-and-tie model and closed-form design formula", Engineering Structures, Vol. 84, (2015), 430-438.
  3. Mata-Falcón, J., Pallarés, L. and Miguel, P.F., "Proposal and experimental validation of simplified strut-and-tie models on dapped-end beams", Engineering Structures, Vol. 183, (2019), 594-609.
  4. Pan, Z., Guner, S. and Vecchio, F.J., "Modeling of interior beam-column joints for nonlinear analysis of reinforced concrete frames", Engineering Structures, Vol. 142, (2017), 182-191.
  5. Committee, A., "Building code requirements for structural concrete (aci 318-08) and commentary, American Concrete Institute. (2008).
  6. Institution, B.S., "Eurocode 2: Design of concrete structures: Part 1-1: General rules and rules for buildings, British Standards Institution, (2004).
  7. Engineers, J.S.o.C., "Jsce guidelines for concrete no. 15: Standard specifications for concrete structures—2007 “design”", (2010).
  8. Chowdhury, S. and Loo, Y., "Complexities and effectiveness of australian standard for concrete structures—as 3600-2018", in EASEC16: Proceedings of The 16th East Asian-Pacific Conference on Structural Engineering and Construction, 2019, Springer. (2021), 1747-1756.
  9. Doğan-Sağlamtimur, N., Bilgil, A. and Öztürk, B., Reusability of ashes for the building sector to strengthen the sustainability of waste management, in Handbook of research on supply chain management for sustainable development. 2018, IGI Global.265-281.
  10. Ponnada, M.R. and Kameswari, P., "Construction and demolition waste management–a review", Safety, Vol. 84, (2015), 19-46.
  11. Nurhanim, A., "State of art reviews on physico-chemical properties of waste concrete aggregate from construction and demolition waste", Iranian (Iranica) Journal of Energy & Environment, Vol. 13, No. 4, (2022), 340-348.
  12. Al Martini, S., Khartabil, A. and Neithalath, N., "Rheological properties of recycled aggregate concrete incorporating supplementary cementitious materials", ACI Materials Journal, Vol. 118, No. 6, (2021), 241-253.
  13. Singh, R.B. and Singh, B., "Rheological behaviour of different grades of self-compacting concrete containing recycled aggregates", Construction and Building Materials, Vol. 161, (2018), 354-364.
  14. Bilgil, A., Ozturk, B. and Bilgil, H., "A numerical approach to determine viscosity-dependent segregation in fresh concrete", Applied Mathematics and Computation, Vol. 162, No. 1, (2005), 225-241.
  15. Çakır, Ö., "Experimental analysis of properties of recycled coarse aggregate (rca) concrete with mineral additives", Construction and Building Materials, Vol. 68, (2014), 17-25.
  16. Pawar, A.J. and Suryawanshi, S., "Comprehensive analysis of stress-strain relationships for recycled aggregate concrete", International Journal of Engineering, Transactions B: Applications, , Vol. 35, No. 11, (2022), 2102-2110.
  17. Masne, N. and Suryawanshi, S., "Analytical and experimental investigation of recycled aggregate concrete beams subjected to pure torsion", International Journal of Engineering, Transactions A: Basics, Vol. 35, No. 10, (2022), 1959-1966.
  18. Sahoo, D.K., Singh, B. and Bhargava, P., "An appraisal of design provisions for bottle-shaped struts", Magazine of Concrete Research, Vol. 64, No. 7, (2012), 647-656.
  19. Sahoo, D.K., Singh, B. and Bhargava, P., "Minimum reinforcement for preventing splitting failure in bottle-shaped struts", ACI Structural Journal, Vol. 108, No. 2, (2011), 206.
  20. Specifications, A.-L.B.D., "American association of state highway and transportation officials", Washington, DC, (2012).
  21. Chaudhari, A.D. and Suryawanshi, S.R., An assessment of efficiency factors of recycled aggregate concrete bottle-shaped struts, in Sustainable building materials and construction: Select proceedings of icsbmc 2021. 2022, Springer.271-277.
  22. Choi, H., Yi, C., Cho, H. and Kang, K., "Experimental study on the shear strength of recycled aggregate concrete beams", Magazine of Concrete Research, Vol. 62, No. 2, (2010), 103-114.
  23. Han, B., Yun, H. and Chung, S., "Shear capacity of reinforced concrete beams made with recycled-aggregate", Special Publication, Vol. 200, (2001), 503-516.
  24. Singh, B., Sahoo, D.K. and Jacob, N.M., "Efficiency factors of recycled aggregate concrete bottle-shaped struts", Magazine of Concrete Research, Vol. 65, No. 14, (2013), 878-887.
  25. Fathifazl, G., Razaqpur, A., Isgor, O.B., Abbas, A., Fournier, B. and Foo, S., "Shear strength of reinforced recycled concrete beams without stirrups", Magazine of Concrete Research, Vol. 61, No. 7, (2009), 477-490.
  26. Kim, S.-W., Jeong, C.-Y., Lee, J.-S. and Kim, K.-H., "Size effect in shear failure of reinforced concrete beams with recycled aggregate", Journal of Asian Architecture and Building Engineering, Vol. 12, No. 2, (2013), 323-330.
  27. Etman, E.E., Afefy, H.M., Baraghith, A.T. and Khedr, S.A., "Improving the shear performance of reinforced concrete beams made of recycled coarse aggregate", Construction and Building Materials, Vol. 185, (2018), 310-324.
  28. Aly, S.A., Ibrahim, M.A. and Khttab, M.M., "Shear behavior of reinforced concrete beams casted with recycled coarse aggregate", European Journal of Advances in Engineering and Technology, Vol. 2, No. 9, (2015), 59-71.
  29. Al-Zahraa, F., El-Mihilmy, M.T. and Bahaa, T., "Experimental investigation of shear strength of concrete beams with recycled concrete aggregates", International Journal of Materials and Structural Integrity, Vol. 5, No. 4, (2011), 291-310.
  30. Lian, O.C., Wee, L.S., Masrom, M.A.a. and Hua, G.C., "Experimental study on shear behaviour of high strength reinforced recycled concrete beam", Pertanika Journal of Science and Technology, Vol. 21, (2013), 601-610.
  31. Arabiyat, S., Katkhuda, H. and Shatarat, N., "Influence of using two types of recycled aggregates on shear behavior of concrete beams", Construction and Building Materials, Vol. 279, (2021), 122475.
  32. Li, C., Liang, N., Zhao, M., Yao, K., Li, J. and Li, X., "Shear performance of reinforced concrete beams affected by satisfactory composite-recycled aggregates", Materials, Vol. 13, No. 7, (2020), 1711.
  33. Standard, I., "Is 10262: Guidelines for concrete mix design proportioning", Indian Standard, New Delhi, (2009).
  34. Visvesvarya, H., Is 456: Plain and reinforced concrete-code of practice. 2000, Bureau of Indian Standards.
  35. Brown, M.D. and Bayrak, O., "Minimum transverse reinforcement for bottle-shaped struts", ACI Structural Journal, Vol. 103, No. 6, (2006), 813.
  36. Collins, M.P. and Mitchell, D., "Rational approach to shear design--the 1984 canadian code provisions", in Journal Proceedings. Vol. 83, (1986), 925-933.