This is an open access article distributed under the CC BY 4.0
This paper proposes a new model for predicting the axial capacity and behavior of Fiber Reinforced Polymer-reinforced concrete (FRP-RC) columns using a promising variant of Genetic Expression Programming (GEP). Current design codes, such as the ACI 440.1R-15 and the Canadian Code CSA S806, disregard the compressive contribution of FRP bars when used in compression members. The behavior of concentrically short FRP-RC columns has been widely investigated in the past few years; however, limited research has been dedicated to investigating the effect of load eccentricity and the slenderness ratio of FRP-RC columns. In addition, the methodologies adopted for including the effect of column slenderness remain a subject of debate, as no solid conclusions are withdrawn in this regard. In this paper, the experimental results of FRP-RC columns are gathered from the literature and used to formulate two GEP models to predict the axial capacity based on load eccentricity. The experimental data includes columns reinforced with different FRP types and subjected to concentric and eccentric axial compressive loads. In addition, the database comprises short and slender columns. The proposed GEP models are functions of concrete compressive strength, longitudinal reinforcing bars ratio, FRP bars elastic modulus, eccentricity level, and column dimensions. For the aim of comparison, a preliminary evaluation of previously suggested empirical equations/models for estimating the axial capacity of FRP-RC columns was carried out over the collected database. The proposed models showed superior accuracy in axial capacity prediction with coefficients of determination R2 equals to 0.978 and R2 equal to 0.992 for eccentric and concentric axial load, respectively. The proposed models were found to give reliable estimates of the axial capacity of columns reinforced with FRP longitudinal bars. Finally, a parametric study to evaluate the effect of each variable on the proposed models was conducted.
1. Tarawneh, A., Almasabha, G. and Murad, Y., (2022). ColumnsNet: Neural Network Model for Constructing Interaction Diagrams and Slenderness Limit for FRP-RC Columns. Journal of Structural Engineering, 148(8), p.04022089.
2. Peng, F., & Xue, W. (2019). Reliability Analysis of Eccentrically Loaded Concrete Rectangular Columns Reinforced with Fiber-Reinforced Polymer Bars. ACI Structural Journal, 116(4).
3. Salah-Eldin, A., Mohamed, H. M., & Benmokrane, B. (2019). Structural performance of high-strength-concrete columns reinforced with GFRP bars and ties subjected to eccentric loads. Engineering Structures, 185, 286-300.
4. Peng, F. and Xue, W., 2019. Reliability Analysis of Eccentrically Loaded Concrete Rectangular Columns Reinforced with Fiber-Reinforced Polymer Bars. ACI Structural Journal, 116(4), pp.275-284.
5. ACI Committee 440, 2015, “Guide for the Design and Construction of Structural Concrete Reinforced with FRP Bars (ACI 440.1R-15),” American Concrete Institute, Farmington Hills, MI, 83 pp.
6. Canadian Standards Association (CSA), 2012, “Design and Construction of Building Components with Fiber Reinforced Polymers (CAN/CSAS806-12),” CSA Group, Rexdale, ON, Canada, 208 pp.
7. De Luca, A.; Matta, F.; and Nanni, A., “Behavior of Full-Scale Glass Fiber-Reinforced Polymer Reinforced Concrete Columns under Axial Load,” ACI Structural Journal, V. 107, No. 5, Sept.-Oct. 2010, pp. 589-596
8. Alsayed, S. H.; Al-Salloum, Y. A.; Almusallam, T. H.; and Amjad, M. A., “Concrete Columns Reinforced by GFRP Rods,” Fourth International Symposium on Fiber-Reinforced Polymer Reinforcement for Reinforced Concrete Structures, SP-188, C. W. Dolan, S. H. Rizkalla, and A. Nanni, eds., American Concrete Institute, Farmington Hills, MI, 1999, pp. 103-112.
9. Elchalakani, M., and Ma, G., 2017, “Tests of Glass Fibre Reinforced Polymer Rectangular Concrete Columns Subjected to Concentric and Eccentric Axial Loading,” Engineering Structures, V. 151, pp. 93-104. doi: 10.1016/j.engstruct.2017.08.023
10. Hadhood, A.; Mohamed, H. M.; and Benmokrane, B., 2017, “Axial Load-Moment Interaction Diagram of Circular Concrete Columns Reinforced with CFRP Bars and Spirals: Experimental and Theoretical Investigations,” Journal of Composites for Construction, ASCE, V. 21, No. 2, Apr., p. 04016092 doi: 10.1061/(ASCE)CC.1943-5614.0000748
11. Tobbi, Hany, Farghaly, Ahmed Sabry, & Benmokrane, Brahim. (2012). Concrete Columns Reinforced Longitudinally and Transversally with Glass Fiber-Reinforced Polymer Bars. ACI Structural Journal, 109(4). https://doi.org/10.14359/51683874
12. Afifi, M. Z., Mohamed, H. M., & Benmokrane, B. (2014). Axial Capacity of Circular Concrete Columns Reinforced with GFRP Bars and Spirals. Journal of Composites for Construction, 18(1), 04013017. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000438
13. Guérin, M.; Mohamed, H. M.; Benmokrane, B.; Nanni, A.; and Shield, C. K., 2018a, “Eccentric Behavior of Full-Scale Reinforced Concrete Columns with Glass Fiber-Reinforced Polymer Bars and Ties,” ACI Structural Journal, V. 115, No. 2, Mar., pp. 489-499. doi: 10.14359/51701107.
14. Guérin, M.; Mohamed, H. M.; Benmokrane, B.; Shield, C. K.; and Nanni, A., 2018b, “Effect of Glass Fiber-Reinforced Polymer Reinforcement Ratio on Axial-Flexural Strength of Reinforced Concrete Columns,” ACI Structural Journal, V. 115, No. 4, July, pp. 1049-1061. doi: 10.14359/51701279
15. Raza, A., Shah, S. A. R., ul Haq, F., Arshad, H., Raza, S. S., Farhan, M., & Waseem, M. (2020, December). Prediction of axial load-carrying capacity of GFRP-reinforced concrete columns through artificial neural networks. In Structures (Vol. 28, pp. 1557-1571). Elsevier.
16. Kisi, Ö., & Çobaner, M. (2009). Modeling River Stage-Discharge Relationships Using Different Neural Network Computing Techniques. CLEAN - Soil, Air, Water, 37(2), 160–169. https://doi.org/10.1002/clen.200800010
17. Solhmirzaei, R., Salehi, H., Kodur, V. and Naser, M.Z., 2020. Machine learning framework for predicting failure mode and shear capacity of ultra-high performance concrete beams. Engineering structures, 224, p.111221.
18. Tarawneh, A., Almasabha, G., Alawadi, R. and Tarawneh, M., 2021, August. Innovative and reliable model for shear strength of steel fibers reinforced concrete beams. In Structures (Vol. 32, pp. 1015-1025). Elsevier.
19. Imam, R., Murad, Y., Asi, I. and Shatnawi, A., 2021. Predicting pavement condition index from international roughness index using gene expression programming. Innovative Infrastructure Solutions, 6(3), pp.1-12.
20. Xue, W.; Peng, F.; and Fang, Z., 2018, “Behavior and Design of Slender Rectangular Concrete Columns Longitudinally Reinforced with Fiber-Reinforced Polymer Bars,” ACI Structural Journal, V. 115, No. 2, Mar., pp. 311-322. doi: 10.14359/51701131
21. Amer, A.; Arockiasamy, M.; and Shahawy, M., 1996, “Ultimate Strength of Eccentrically Loaded Concrete Columns Reinforced with CFRP Bars,” Proceedings of the Conference on Advanced Composite Materials in Bridges and Structures, Montreal, QC, Canada, pp. 209-216.
22. Sharbatdar, M. K., 2003, “Concrete Columns and Beams Reinforced with FRP Bars and Grids under Monotonic and Reversed Cyclic Loading,” PhD dissertation, University of Ottawa, Ottawa, ON, Canada, 371 pp.
23. Tikka, T. K.; Francis, M.; and Teng, B., 2010, “Strength of Concrete Beam Columns Reinforced with GFRP Bars,” 2nd International Structures Specialty Conference, Winnipeg, MB, Canada, pp. 1194-1203.
24. Gong, Y.; and Zhang, J., 2009, “Experimental Study of Reinforced Concrete Eccentric Compression Columns with CFRP Tendons,” China Civil Engineering Journal, V. 42, No. 10, Oct., pp. 46-52. (in Chinese) doi:10.15951/j.tmgcxb.2009.10.012
25. Elchalakani, M.; Karrech, A.; Dong, M.; Ali, M.; and Yang, B., 2018, “Experiments and Finite Element Analysis of GFRP Reinforced Geopolymer Concrete Rectangular Columns Subjected to Concentric and Eccentric Axial Loading,” Structures, V. 14, June, pp. 273-289. doi: 10.1016/j.istruc.2018.04.001
26. Khorramian, K., and Sadeghian, P., 2017, “Experimental and Analytical Behavior of Short Concrete Columns Reinforced with GFRP Bars under Eccentric Loading,” Engineering Structures, V. 151, Nov, pp. 761-773. doi: 10.1016/j.engstruct.2017.08.064
27. Sun, L.; Wei, M.; and Zhang, N., 2017, “Experimental Study on the Behavior of GFRP Reinforced Concrete Columns under Eccentric Axial Load,” Construction and Building Materials, V. 152, Oct., pp. 214-225. doi: 10.1016/j.conbuildmat.2017.06.159
28. Issa, M.S., Metwally, I.M. and Elzeiny, S.M., 2011. Structural performance of eccentrically loaded GFRP reinforced concrete columns. International Journal of Civil & Structural Engineering, 2(1), pp.395-406.
29. Othman, Z.S. and Mohammad, A.H., 2019. Behaviour of Eccentric Concrete Columns Reinforced with Carbon Fibre-Reinforced Polymer Bars. Advances in Civil Engineering, 2019.
30. Salah-Eldin, A., Mohamed, H.M. and Benmokrane, B., 2019. Structural performance of high-strength-concrete columns reinforced with GFRP bars and ties subjected to eccentric loads. Engineering Structures, 185, pp.286-300.
31. Hadi, M.N., Karim, H. and Sheikh, M.N., 2016. Experimental investigations on circular concrete columns reinforced with GFRP bars and helices under different loading conditions. Journal of Composites for Construction, 20(4), p.04016009.
32. Khorramian, K. and Sadeghian, P., 2019, April. Behavior of Slender GFRP Reinforced Concrete Columns. In ASCE-SEI Structures Congress 2019. American Society of Civil Engineers.
33. Abdelazim, W., Mohamed, H. M., Benmokrane, B., & Afifi, M. Z. (2020). Effect of critical test parameters on behavior of glass fiber-reinforced polymer-reinforced concrete slender columns under eccentric load. ACI Structural Journal, 117(4), 127-141.
34. Khorramian, K., & Sadeghian, P. (2020). Experimental Investigation of Short and Slender Rectangular Concrete Columns Reinforced with GFRP Bars under Eccentric Axial Loads. Journal of Composites for Construction, 24(6), 04020072.
35. Maranan, G. B., Manalo, A. C., Benmokrane, B., Karunasena, W., & Mendis, P. (2016). Behavior of concentrically loaded geopolymer-concrete circular columns reinforced longitudinally and transversely with GFRP bars. Engineering Structures, 117, 422-436.
36. Elmesalami, N., Abed, F., & Refai, A. E. (2021). Concrete columns reinforced with GFRP and BFRP bars under concentric and eccentric loads: Experimental testing and analytical investigation. Journal of Composites for Construction, 25(2), 04021003.
37. Mohamed, H. M.; Afifi, M. Z.; and Benmokrane, B., “Performance Evaluation of Concrete Columns Reinforced Longitudinally with FRP Bars and Confined with FRP Hoops and Spirals under Axial Load,” Journal of Bridge Engineering, ASCE, V. 19, No. 7, 2014, p. 04014020. doi: 10.1061/(ASCE)BE.1943-5592.0000590.