Lap shear-prestressed bond test to evaluate prestressed FRP concrete joint

Document Type : Research Note

Authors

1 PhD student, Department of Civil Engineering, Isfahan University of Technology (IUT), Isfahan, Iran

2 Professor, Department of Civil Engineering, Isfahan University of Technology (IUT), Isfahan, Iran.

3 Assistant Professor, Department of Civil Engineering, Isfahan University of Technology (IUT), Isfahan, Iran.

10.24200/j30.2024.63429.3273

Abstract

The use of FRP composites as an effective method for strengthening reinforced concrete structures has been a subject of research due to its numerous benefits. A common failure mode in the application of these composites is the debonding of the FRP sheet from the concrete surface, which can sometimes reduce the capacity of these composites to as low as 10% of their total capacity. As a result, researchers have begun to prestress the FRP sheets and strengthen them with prestressed FRP to optimize the efficiency of these materials. A crucial aspect in the strengthening of a reinforced concrete member with an FRP sheet is the examination of the connection behavior between the FRP sheet and concrete. The significance of this issue has led to dedicated research and experimentation in this field. In this study, a prestress-lab shear test was employed for the first time to investigate the bond behavior of prestressed FRP composites-to-concrete joints. Additionally, the particle image velocimetry (PIV) method was used for result analysis. To verify the effectiveness of this method, eight tests were conducted on prism specimens measuring 150×150×350 mm. The strengthening methods of the specimens involved the use of external bonded reinforcement (EBR) and external bonded reinforcement on grooves (EBROG) methods. Furthermore, the specimens were prestressed at different levels, including 0%, 20%, and 30% of the ultimate strain of FRP composites. This study examined the specimens in terms of bond strength capacity, failure mode, and stress and strain distribution on the joint surface. The results showed that prestressing increased the bond strength by 70% in the EBR method. Moreover, the bond strength of the EBROG specimen with 20% prestressing increased by 123% compared to the control specimen. These findings indicate that prestressing using the EBROG method is a viable technique for enhancing the performance of FRP-to-concrete joints.

Keywords

Main Subjects

References

1. ACI Committee 440.2R-17., 2017. Guide for the design and construction of externally bonded FRP systems for strengthening existing structures, American Concrete Institute (ACI), https://doi.org/10.14359/51700867. 2. Ueda, T. and Dai, J., 2005. Interface bond between FRP sheets and concrete substrates: properties, numerical modeling and roles in member behaviour. Progress in Structural Engineering and Materials, 7(1), pp.27-43. https://doi.org/10.1002/pse.187. 3. El‐Hacha, R., Wight, R.G. and Green, M.F., 2001. Prestressed fibre‐reinforced polymer laminates for strengthening structures. Progress in Structural Engineering and Materials, 3(2), pp.111-121. https://doi.org/10.1002/pse.76. 4. Lin, T. Y., and Burns, N. H., 1963. Design of prestressed concrete structures, Book Design of prestressed concrete structures, Series Design of prestressed concrete structures, ed., Editor eds., Wiley New York. 5. Michels, J., Zile, E., Czaderski, C. and Motavalli, M., 2014. Debonding failure mechanisms in prestressed CFRP/epoxy/concrete connections. Engineering Fracture Mechanics, 132, pp.16-37. https://doi.org/10.1016/j.engfracmech.2014.10.012. 6. Shabani, E., Mostofinejad, D. and Saljoughian, A., 2023. Bond behavior of prestressed FRP sheet-concrete joints: Comparison of EBROG and EBR methods. Construction and Building Materials, 400, p.132752. https://doi.org/10.1016/j.conbuildmat.2023.132752. 7. Moshiri, N., Czaderski, C., Mostofinejad, D. and Motavalli, M., 2021. Bond resistance of prestressed CFRP strips attached to concrete by using EBR and EBROG strengthening methods. Construction and Building Materials, 266, p.121209. https://doi.org/10.1016/j.conbuildmat.2020.121209. 8. Moshiri, N., Martinelli, E., Czaderski, C., Mostofinejad, D., Hosseini, A. and Motavalli, M., 2023. Bond behavior of prestressed CFRP strips-to-concrete joints using the EBROG method: experimental and analytical evaluation. Journal of Composites for Construction, 27(1), p.04022104. https://doi.org/10.1061/jccof2.cceng-3851. 9. Garden, H.N. and Hollaway, L.C., 1998. An experimental study of the failure modes of reinforced concrete beams strengthened with prestressed carbon composite plates. Composites Part B: Engineering, 29(4), pp.411-424. https://doi.org/10.1016/s1359-8368(97)00043-7. 10. Shang, S., Zou, P.X., Peng, H. and Wang, H., 2005, December. Avoiding de-bonding in FRP strengthened reinforced concrete beams using prestressing techniques. In Proceedings of the international symposium on Bond behaviour of FRP in structures (BBFS). Hong Kong, China (pp. 321-28). 11. Nordin, H. and Täljsten, B., 2006. Concrete beams strengthened with prestressed near surface mounted CFRP. Journal of composites for construction, 10(1), pp.60-68. https://doi.org/10.1061/(asce)1090-0268(2006)10:1(60). 12. Gaafar, M.A. and El-Hacha, R., 2007. Prestressing concrete beams using NSM FRP technique. In Proceedings of International Symposium on Fiber-Reinforced Polymer Reinforcement in Concrete Structures. FRPRCS-8, Partas, Greece (pp. 8-11). 13. Kim, Y.J., Wight, R.G. and Green, M.F., 2008. Flexural strengthening of RC beams with prestressed CFRP sheets: Development of nonmetallic anchor systems. Journal of Composites for Construction, 12(1), pp.35-43. https://doi.org/10.1061/(asce)1090-0268(2008)12:1(35). 14. Hajihashemi, A., Mostofinejad, D. and Azhari, M., 2011. Investigation of RC beams strengthened with prestressed NSM CFRP laminates. Journal of Composites for Construction, 15(6), pp.887-895. https://doi.org/10.1061/(asce)cc.1943-5614.0000225. 15. Czaderski-Forchmann, C., 2012. Strengthening of reinforced concrete members by prestressed, externally bonded reinforcement with gradient anchorage (Doctoral dissertation, ETH Zurich). 16. Mostofinejad, D. and Mahmoudabadi, E., 2010. Grooving as alternative method of surface preparation to postpone debonding of FRP laminates in concrete beams. Journal of composites for construction, 14(6), pp.804-811. https://doi.org/10.1061/(asce)cc.1943-5614.0000117. 17. Mostofinejad, D. and Shameli, S.M., 2013. Externally bonded reinforcement in grooves (EBRIG) technique to postpone debonding of FRP sheets in strengthened concrete beams. Construction and Building Materials, 38, pp.751-758. https://doi.org/10.1016/j.conbuildmat.2012.09.030. 18. Saljoughian, A. and Mostofinejad, D., 2020. RC columns longitudinally strengthened via novel EBRIOG technique. Structural Concrete, 21(2), pp.570-586. https://doi.org/10.1002/suco.201900151. 19. Saljoughian, A. and Mostofinejad, D., 2018. Grooving methods in square RC columns strengthened with longitudinal CFRP under cyclic axial compression. Engineering Structures, 174, pp.724-735. https://doi.org/10.1016/j.engstruct.2018.08.007. 20. Saljoughian, A. and Mostofinejad, D., 2016. Axial-flexural interaction in square RC columns confined by intermittent CFRP wraps. Composites Part B: Engineering, 89, pp.85-95. https://doi.org/10.1016/j.compositesb.2015.10.047. 21. Saljoughian, A. and Mostofinejad, D., 2018. Grooving methods in square RC columns strengthened with longitudinal CFRP under cyclic axial compression. Engineering Structures, 174, pp.724-735. https://doi.org/10.1016/j.engstruct.2018.08.007. 22. ACI 211.1-91., 2009. Standard practice for selecting proportions for normal, heavyweight and mass concrete (Reapproved 2009), American Concrete Institute, Farming Hills, MI, USA. https://doi.org/10.14359/10987. 23. http://www.sika.com 24. http://www.quantomEPR3301.co.uk 25. Moghaddas, A., Mostofinejad, D. and Ilia, E., 2019. Empirical FRP-concrete effective bond length model for externally bonded reinforcement on the grooves. Composites Part B: Engineering, 172, pp.323-338. https://doi.org/10.1016/j.compositesb.2019.05.068. 26. ASTM D5868-01., 2014. Standard test method for lap shear adhesion for fiber reinforced plastic (FRP) bonding, West Conshohocken, pa. https://doi.org/10.1520/D5868-01R14. 27. ASTM C 39-05., 2009. Standard test method for compressive strength of cylindrical concrete specimens, American Standard Test Method (ASTM).

Files

Share

How to cite

Statistics