Prediction of Immediate Deflections for RC Beams Using Stress-varying Modulus of Elasticity

Year 2022, Volume: 9 Issue: 4, 516 - 525, 31.12.2022

Eray Özbek

https://doi.org/10.54287/gujsa.1195506

Abstract

This paper discusses the immediate deflection calculation of reinforced concrete beams and their consistency with the experimental results. For this purpose, a total of six T-beams with low, medium, and high reinforcement ratios were tested and then, deflection behavior was compared with the well-known Branson (1965) and Bischoff (2005) approaches. Although both approaches could yield close results for the low reinforcement at service loads by using a constant modulus of elasticity, they underestimated the deflections of medium and highly reinforced beams. Thus, the nonlinear behavior of concrete that changes with stress was also considered in the subsequent analyzes. As a result, the developed new approach could predict the experimental deformations very accurately, especially at the level of service loads.

Keywords

Beam, Deflection, Serviceability, Elastic Modulus, Concrete Model

References

• AASHTO. (2005). LRFD bridge design specifications, American Association of State Highway and Transportation Officials, USA.
• ACI 318-14. (2014). Building code requirements for structural concrete and commentary, American Concrete Institute, USA.
• ACI 318-19. (2019). Building code requirements for structural concrete and commentary. American Concrete Institute, USA.
• ACI 435R-95. (2000). Control of deflection in concrete structure. American Concrete Institute, USA.
• AS 3600-2009. (2009). Australian standard for concrete structures. Standards Australia, Australia.
• Ammash, H., Hemzah, S., & Al-Ramahee, M. (2018). Unified advanced model of effective moment of ınertia of reinforced concrete members. International Journal of Applied Engineering Research, 13(1), 557-563.
• Arabshahi, A., Tavakol, M., Sabzi, J., & Gharaei-Moghaddam, N. (2022). Prediction of the effective moment of inertia for concrete beams reinforced with FRP bars using an evolutionary algorithm. Structures, 35, 684-705. doi:10.1016/j.istruc.2021.11.011
• Bischoff, P. H. (2005). Revaluation of deflection prediction for concrete beams reinforced with steel and fiber reinforced polymer bars. Journal of Structural Engineering, 131(5), 752-767. doi:10.1061/(ASCE)0733-9445(2005)131:5(752)
• Bischoff, P. H. (2020). Comparison of existing approaches for computing deflection of reinforced concrete. ACI Structural Journal, 117(1), 231-240. doi:10.14359/51718072
• Branson, D. E. (1965). Instantaneous and time-dependent deflection on simple and continuous reinforced concrete beams (HPR Report No.7), Highway Department Bureau of Public Roads, USA.
• Carreira, D. J. & Chu, K. D. (1985). Stress-strain relationship for plain concrete in compression. ACI Journal Proceedings, 82(6), 797-804.
• CEB-FIB. (1970). International recommendations for the design and construction of concrete structures: principles and recommendations, Comité Euro-International-Federation Internationale de la Précontrainte, London, UK.
• CSA A23.3-04. (2004). Design of concrete structures, Canadian Standards Association, Canada.
• Desayi, P. & Krishnan S. (1964). Equation for the stress strain curve of concrete. ACI Journal Proceedings, 61(3), 345-350.
• Hognestad, E. (1951). A study of combined bending axial load in reinforced concrete members. University of Illinois Bulletin Series No. 399. The University of Illinois Engineering Experimental Station, USA.
• Hognestad, E., Hanson, N. W., & McHenry, D. (1955). Concrete stress distribution in ultimate strength design. ACI Journal Proceedings, 52(4), 455-480. doi:10.14359/11609
• Kalkan, İ. (2010). Deflection prediction for reinforced concrete beams through different effective moment of ınertia expressions. International Journal of Engineering Research and Development, 5(1), 72-80.
• Kim, S.-W., Han, D.-S., & Kim, K.-H. (2021). Evaluation of shear effect on deflection of RC beams. Applied Sciences, 11(16), 7690. doi:10.3390/app11167690
• Kumar, P. A. (2004). Compact analytical material model for unconfined concrete under uni-axial compression. Materials and Structures, 37(9), 585-590. doi:10.1007/BF02483287
• Mancuso, C., & Bartlett, F. M. (2017). ACI 318-14 criteria for computing instantaneous deflections. ACI Structural Journal, 114(5), 1299-1310. doi:10.14359/51689726
• Popovics, S. A. (1973). Numerical approach to the complete stress-strain curve of concrete. Cement and Concrete Research, 3(5), 583-599. doi:10.1016/0008-8846(73)90096-3
• Todeschini, C. E, Bianchini, A. C., & Kesler, C. E. (1964). Behavior of concrete columns reinforced with high strength steels. ACI Journal Proceedings, 61(6), 701-716.
• TS500. (2000). Requirements for design and construction of reinforced concrete structures, Turkish Standarts Institute, Turkey.