Advances in concrete construction

Techno-Press (테크노프레스)
권호 표지
DOI QR코드

DOI QR Code

Preload effects on behaviour of FRP confined concrete: Experiment, mechanism and modified model

  • Cao, Vui Van (Faculty of Civil Engineering, Ho Chi Minh City University of Technology (HCMUT))
  • Received : 2019.03.15
  • Accepted : 2020.05.29
  • Published : 2020.06.25
⟨ Previous Next ⟩

Abstract

Stress-strain models of fibre reinforced polymer (FRP) confined concrete have been widely investigated; however, the existing load which is always supported by structures during the retrofitting phase, namely 'preload', has been neglected. Thus, preload effects should be clarified, providing insightful information for FRP retrofitting of structures with preload conditions. Towards this aim, experiments were performed for 27 cylinder concrete specimens with the diameter 150 mm and the height 300 mm. Three specimens were used to test the compressive strength of concrete to compute the preloads 20%, 30% and 40% of the average strength of these specimens. Other 24 specimens were divided into 2 groups; each group included 4 subgroups. Four subgroups were subjected to the above preloads and no preload, and were then wrapped by 2 FRP layers. Similar designation is applied to group 2, but wrapped by 3 FRP layers. All specimens were tested under axial compression to failure. Explosive failure is found to be the characteristic of specimens wrapped by FRP. Experimental results indicated that the preload decreases 12-13% the elastic and second stiffness of concrete specimens wrapped by 2 FRP layers. The stiffness reduction can be mitigated by the increase of FRP layers. Preload negligibly reduces the ultimate force and unclearly affects the ultimate displacement probably due to complicated cracks developed in concrete. A mechanism of preload effects is presented in the paper. Finally, to take into account preload effects, a modification of the widely used model of un-preload FRP confined concrete is proposed and the modified model demonstrated with a reasonable accuracy.

Keywords

Acknowledgement

This research is funded by Ho Chi Minh city University of Technology-VNU-HCM under grant number T-KTXD-2019-16. The author would like to express special thanks to staffs in the Laboratory of Structural Engineering and Laboratory of Mechanics of Materials and Structures, Department of Civil Engineering, Ho Chi Minh city University of Technology (HCMUT)-Vietnam National University for their help and encouragement. The author also thanks Dr. Hung The Dinh, Carboneering company Ltd. (www.carboneering.com), for providing CFRP material which was used for the experiment. The authors would like to express thanks to workers for their help on physical work with reasonable payment.

References

  1. Abdel-Kareem, A.H. (2014), "Shear strengthening of reinforced concrete beams with rectangular web openings by FRP Composites", Adv. Concrete Constr., 2(4), 281-300. https://doi.org/10.12989/acc.2014.2.4.281.
  2. ACI (2008), Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures (ACI 440.2R-08).
  3. Ahmad, H., Hameed, R., Riaz, M.R. and Gillani, A.A. (2018), "Strengthening of concrete damaged by mechanical loading and elevated temperature", Adv. Concrete Constr., 6(6), 645-658. https://doi.org/10.12989/acc.2018.6.6.645.
  4. Baji, H. (2017), "Calibration of the FRP resistance reduction factor for FRP-confined reinforced concrete building columns", J. Compos. Constr., 21(3), 04016107. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000769.
  5. Baji, H., Ronagh, H.R. and Li, C.Q. (2016), "Probabilistic design models for ultimate strength and strain of FRP-confined concrete", J. Compos. Constr., 20(6), 04016051. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000704.
  6. Balsamo, A., Colombo, A., Manfredi, G., Negro, P. and Prota, A. (2005), "Seismic behavior of a full-scale RC frame repaired using CFRP laminates", Eng. Struct., 27, 769-780. https://doi.org/10.1016/j.engstruct.2005.01.002.
  7. Berthet, J.F., Ferrier, E. and Hamelin, P. (2006), "Compressive behavior of concrete externally confined by composite jackets: Part B: modeling", Constr. Build. Mater., 20(5), 338-347. https://doi.org/10.1016/j.conbuildmat.2005.01.029.
  8. Cao, V.V. and Pham, S.Q. (2019), "Comparison of CFRP and GFRP wraps on reducing seismic damage of deficient reinforced concrete structures", Int. J. Civil Eng., 17(11), 1667-1681. https://doi.org/10.1007/s40999-019-00429-y.
  9. Cao, V.V. and Ronagh, H.R. (2014), "Reducing the seismic damage of reinforced concrete frames using FRP confinement", Compos. Struct., 118, 403-415. https://doi.org/10.1016/j.compstruct.2014.07.038.
  10. Eslami, A. and Ronagh, H.R. (2013), "Effect of FRP wrapping in seismic performance of RC buildings with and without special detailing-A case study", Compos. Part B: Eng., 45(1), 1265-1274. https://doi.org/10.1016/j.compositesb.2012.09.031.
  11. Ferrotto, M.F., Fischer, O. and Cavaleri, L. (2018), "Analysis-oriented stress-strain model of CRFP-confined circular concrete columns with applied preload", Mater. Struct., 51(2), 44. https://doi.org/10.1617/s11527-018-1169-0.
  12. Garcia, R., Hajirasouliha, I. and Pilakoutas, K. (2010), "Seismic behaviour of deficient RC frames strengthened with CFRP composites", Eng. Struct., 32, 3075-3085. https://doi.org/10.1016/j.engstruct.2010.05.026.
  13. Harajli, M.H. and Rteil, A.A. (2004), "Effect of confinement using fiber-reinforced polymer or fiber-reinforced concrete on seismic performance of gravity load-designed columns", ACI Struct. J., 101(1), 47-56.
  14. Harajli, M.H., Hantouche, E. and Soudki, K. (2006), "Stress-strain model for fiber-reinforced polymer jacketed concrete columns", ACI Struct. J., 103(5), 672-682.
  15. Hognestad, E. (1951), "A study of combined bending axial load in reinforced concrete members", Bulletin Series No. 399, 49, Engineering Experimental Station, The University of Illinois., Urbana.
  16. Hosseinpour, F. and Abbasnia, R. (2014), "Experimental investigation of the stress-strain behavior of FRP confined concrete prisms", Adv. Concrete Constr., 2(3), 177-192. https://doi.org/10.12989/acc.2014.2.3.177.
  17. Hosseinpour, F. and Abdelnaby, A.E. (2015), "Statistical evaluation of the monotonic models for FRP confined concrete prisms", Adv. Concrete Constr., 3(3), 161-185. https://doi.org/10.12989/acc.2015.3.3.161.
  18. Lam, L. and Teng, J.G. (2003a), "Design-oriented stress-strain model for FRP-confined concrete", Constr. Build. Mater., 17, 471-489. https://doi.org/10.1016/S0950-0618(03)00045-X.
  19. Lam, L. and Teng, J.G. (2003b), "Design-oriented stress-strain model for FRP-confined concrete in rectangular columns", J. Reinf. Plast. Compos., 22(13), 1149-1186. https://doi.org/10.1177/0731684403035429.
  20. Lao, X., Han, X., Ji, J. and Chen, B. (2019), "The compression behavior of CFRP-repaired damaged square RC columns", Constr. Build. Mater., 223, 1154-1166. https://doi.org/10.1016/j.conbuildmat.2019.07.182.
  21. Ludovico, M.D., Manfredi, G., Mola, E., Negro, P. and Prota, A. (2008a), "Seismic behavior of a full-scale RC structure retrofitted using GFRP laminates", J. Struct. Eng., 134(5), 810-821. https://doi.org/10.1061/(ASCE)0733-9445(2008)134:5(810).
  22. Ludovico, M.D., Prota, A., Manfredi, G. and Cosenza, E. (2008b), "Seismic strengthening of an under-designed RC structure with FRP", Earthq. Eng. Struct. Dyn., 37, 141-162. https://doi.org/10.1002/eqe.749.
  23. Mesbah, H.A. and Benzaid, R. (2017), "Damage-based stress-strain model of RC cylinders wrapped with CFRP composites", Adv. Concrete Constr., 5(5), 539-561. https://doi.org/10.12989/acc.2017.5.5.539.
  24. Mortezaei, A., Ronagh, H.R. and Kheyroddin, A. (2010), "Seismic evaluation of FRP strengthened RC buildings subjected to near-fault ground motions having fling step", Compos. Struct., 92, 1200-1211. https://doi.org/10.1016/j.compstruct.2009.10.017.
  25. Norris, T., Saadatmanesh, H. and Ehsani, M.R. (1997), "Shear and flexural strengthening of R/C beams with carbon fiber sheets", J. Struct. Eng., 123(7), 903-911. https://doi.org/10.1061/(ASCE)0733-9445(1997)123:7(903).
  26. Ozbakkaloglu, T. and Lim, J.C. (2013), "Axial compressive behavior of FRP-confined concrete: Experimental test database and a new design-oriented model", Compos. Part B: Eng., 55, 607-634. https://doi.org/10.1016/j.compositesb.2013.07.025.
  27. Ozcan, O., Binici, B., Canbay, E. and Ozcebe, G. (2010), "Repair and strengthening of reinforced concrete columns with CFRPs", J. Reinf. Plast. Compos., 29(22), 3411-3424. https://doi.org/10.1177/0731684410376332.
  28. Pan, Y., Guo, R., Li, H., Tang, H. and Huang, J. (2017a), "Analysis-oriented stress-strain model for FRP-confined concrete with preload", Compos. Struct., 166, 57-67. https://doi.org/10.1016/j.compstruct.2017.01.007.
  29. Pan, Y., Rui, G., Li, H., Tang, H. and Xu, L. (2017b), "Study on stress-strain relation of concrete confined by CFRP under preload", Eng. Struct., 143, 52-63. https://doi.org/10.1016/j.engstruct.2017.04.004.
  30. Papanikolaou, V.K., Stefanidou, S.P. and Kappos, A.J. (2013), "The effect of preloading on the strength of jacketed R/C columns", Constr. Build. Mater., 38, 54-63. https://doi.org/10.1016/j.conbuildmat.2012.07.100.
  31. Rahai, A. and Akbarpour, H. (2014), "Experimental investigation on rectangular RC columns strengthened with CFRP composites under axial load and biaxial bending", Compos. Struct., 108(0), 538-546. https://doi.org/10.1016/j.compstruct.2013.09.015.
  32. Realfonzo, R. and Napoli, A. (2013), "Confining concrete members with FRP systems: Predictive vs design strain models", Compos. Struct., 104, 304-319. https://doi.org/10.1016/j.compstruct.2013.04.031.
  33. Richard Liew, J.Y. and Xiong, D.X. (2009), "Effect of preload on the axial capacity of concrete-filled composite columns", J. Constr. Steel Res., 65(3), 709-722. https://doi.org/10.1016/j.jcsr.2008.03.023.
  34. Saadatmanesh, H., Ehsani, M.R. and Jin, L. (1997), "Repair of earthquake-damaged RC columns with FRP wraps", ACI Struct. J., 94(2), 206-215.
  35. Sathwik, M.C., Prashanth, M.H., Naik, S.C. and Satish, A. (2019), "Experimental and numerical studies on compressive behaviour of CFRP wrapped cylindrical concrete specimens subjected to different pre-loading conditions", Mater. Today: Proc., 27(1), 327-335. https://doi.org/10.1016/j.matpr.2019.11.041.
  36. Sheikh, S.A. and Yau, G. (2002), "Seismic behavior of concrete columns confined with steel and fiber-reinforced polymers", ACI Struct. J., 99(1), 72-80.
  37. Sumathi, A. and Arun, V.S. (2017), "Study on behavior of RCC beams with externally bonded FRP members in flexure", Adv. Concrete Constr., 5(6), 625-638. https://doi.org/10.12989/acc.2017.5.6.625.
  38. Takeuti, A.R., de Hanai, J.B. and Mirmiran, A. (2008), "Preloaded RC columns strengthened with high-strength concrete jackets under uniaxial compression", Mater. Struct., 41(7), 1251-1262. https://doi.org/10.1617/s11527-007-9323-0.
  39. Tamuzs, V., Tepfers, R., Zile, E. and Ladnova, O. (2006), "Behavior of concrete cylinders confined by a carbon composite 3. Deformability and the ultimate axial strain", Mech. Compos. Mater., 42(4), 303-314. https://doi.org/10.1007/s11029-006-0040-5.
  40. Teng, J.G., Jiang, T., Lam, L. and Luo, Y.Z. (2009), "Refinement of a design-oriented stress-strain model for FRP-confined concrete", J. Compos. Constr., 13(4), 269-278. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000012.
  41. Vandoros, K.G. and Dritsos, S.E. (2006), "Axial preloading effects when reinforced concrete columns are strengthened by concrete jackets", Prog. Struct. Eng. Mater., 8(3), 79-92. https://doi.org/10.1002/pse.215.
  42. Vandoros, K.G. and Dritsos, S.E. (2008), "Concrete jacket construction detail effectiveness when strengthening RC columns", Constr. Build. Mater., 22(3), 264-276. https://doi.org/10.1016/j.conbuildmat.2006.08.019.
  43. Wei, Y.Y. and Wu, Y.F. (2012), "Unified stress-strain model of concrete for FRP-confined columns", Constr. Build. Mater., 26, 381-392. https://doi.org/10.1016/j.conbuildmat.2011.06.037.
  44. Wu, G., Wu, Z.S. and Lu, Z.T. (2007), "Design-oriented stress-strain model for concrete prisms confined with FRP composites", Constr. Build. Mater., 21(5), 1107-1121. https://doi.org/10.1016/j.conbuildmat.2005.12.014.
  45. Youssef, M.N., Feng, M.Q. and Mosallam, A.S. (2007), "Stress-strain model for concrete confined by FRP composites", Compos. Part B: Eng., 38(5-6), 614-628. https://doi.org/10.1016/j.compositesb.2006.07.020.