Prediction of Capacity for Moment Redistribution in FRP-Strengthened Continuous RC T-Beams
Publication: Journal of Composites for Construction
Volume 21, Issue 1
Abstract
Because of the premature debonding of fiber-reinforced polymer (FRP) materials that results in a reduction in ductility, the problem of how to exploit moment redistribution (MR) in FRP-strengthened continuous reinforced concrete (RC) structures is unresolved. To date, limited research has been conducted into MR in such structures; a reliable and rigorous solution for quantifying MR throughout the loading cycle remains elusive. This paper aims to quantify MR and predict the capacity at reasonable accuracy, to encourage the use of FRP for the strengthening of existing continuous RC structures. Experiments conducted on 12 continuous T-beams are reported, and the findings are discussed. Strengthening configuration and anchorage scheme are the main variables. A new analytical strategy is described for quantifying MR, and the analytical results are then validated against the experimental results. Both experimental and analytical results confirm that there is no reason to restrict MR into strengthened zones. More importantly, MR, out of FRP-strengthened zones, can indeed occur, provided that the FRP is sufficiently anchored; reliable exploitation of this is now possible.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
Research funding provided by the Engineering and Physical Sciences Research Council (EPSRC: EP/K019015/1; United Kingdom) and the project partners (Concrete repairs Ltd, Fyfe, Highways England, WSP/Parsons Brinckerhoff and Tony Gee and partners) is acknowledged with appreciative thanks. The authors also sincerely appreciate the assistance of the laboratory staff of the Department of Architecture and Civil Engineering at the University of Bath, U.K. All data created during this research are openly available from the University of Bath data archive at https://doi.org/10.15125/BATH-00178.
References
ACI (American Concrete Institute). (2008). “Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures.” ACI 440.2 R, Farmington Hills, MI.
ACI (American Concrete Institute). (2014). “Building code requirements for structural concrete and commentary.” ACI 318, Farmington Hills, MI.
Aiello, M.A., and Ombres, L. (2011). “Moment redistribution in continuous fiber-reinforced polymer-strengthened reinforced concrete beams.” ACI Struct. J., 108(2), 158–166.
AS (Australia Standards). (2009). “Australian Standard for the design of reinforced concrete.” AS 3600, Homebush, NSW, Australia.
Bagge, N., O’Connor, A., Elfgren, L., and Pedersen, C. (2014). “Moment redistribution in RC beams—A study of the influence of longitudinal and transverse reinforcement ratios and concrete strength.” Eng. Struct., 80, 11–23.
Bondy, K. B. (2003). “Moment redistribution: Principles and practice, using ACI 318-02.” PTI J., 1(1), 3–21.
Breveglieri, M., Barros, J. A., Dalfré, G. M., and Aprile, A. (2012). “A parametric study on the effectiveness of the NSM technique for the flexural strengthening of continuous RC slabs.” Compos. Part B, 43(4), 1970–1987.
BSI (British Standard Institute). (2005). “Structural use of concrete. Code of practice for design and construction.” BS 8110BSI, London.
Concrete Society. (2012). “Design guidance for strengthening concrete structures using fiber composite materials.”, Blackwater Camberley, U.K.
CSA (Canadian Standards Association). (2014). “Design of concrete structures.” CSA-A23.3, National Standard of Canada, Toronto.
Dalfré, G., and Barros, J. (2011). “Flexural strengthening of RC continuous slab strips using NSM CFRP laminates.” Adv. Struct. Eng., 14(6), 1223–1245.
Denton, S. R. (2007). “Achieving sustainable growth in the use of FRP composites in structural rehabilitation.” Proc., Conf. ACIC-2007, Univ. of Bath, Bath, U.K., 50–57.
Duthinh, D., and Starnes, M. (2004). “Strength and ductility of concrete beams reinforced with carbon fibre-reinforced polymer plates and steel.” J. Compos. Constr., 59–69.
El-Refaie, S. A., Ashour, A. F., and Garrity, S. W. (2003). “Sagging and hogging strengthening of continuous reinforced concrete beams using carbon fiber-reinforced polymer sheets.” ACI Struct. J., 100(4), 446–453.
Lee, J. H. (2010). “Performance of U-wrap as an anchorage system in externally-bonded FRP reinforced concrete elements.” Ph.D. thesis, Pennsylvania State Univ., PA.
Lou, T., Lopes, S. M., and Lopes, A. V. (2015). “Neutral axis depth and moment redistribution in FRP and steel reinforced concrete continuous beams.” Compos. Part B, 70, 44–52.
Meier, U., Deuring, M., Meier, H., and Schwegler, G. (1993). CFRP bonded sheets, Elsevier Science, Amsterdam, the Netherlands, 423–434.
Mukhopadhyaya, P., Swamy, N., and Lynsdale, C. (1998). “Optimizing structural response of beams strengthened with GFRP plates.” J. Comp. Constr., 87–95.
Oehlers, D. J. (2006). “Ductility of FRP plated flexural members.” Cem. Concr. Compos., 28(10), 898–905.
Oehlers, D. J., Haskett, M., Ali, M. M., and Griffith, M. C. (2010). “Moment redistribution in reinforced concrete beams.” Proc. Inst. Civ. Eng.–Struct. Build., 163(3), 165–176.
Oehlers, D. J., Ju, G., Liu, I. S. T., and Seracino, R. (2004). “Moment redistribution in continuous plated RC flexural members. Part 1: Neutral axis depth approach and tests.” Eng., Struct., 26(14), 2197–2207.
Santos, P., Laranja, G., França, P. M., and Correia, J. R. (2013). “Ductility and moment redistribution capacity of multi-span T-section concrete beams reinforced with GFRP bars.” Constr. Build. Mater., 49, 949–961.
Silva, P. F., and Ibell, T. J. (2008). “Evaluation of moment distribution in continuous fiber-reinforced polymer-strengthened concrete beams.” ACI Struct. J., 105(6), 729–739.
Tajaddini, A. (2015). “Investigation of moment redistribution in FRP-strengthened RC slabs and T-beams.” Ph.D. thesis, Univ. of Bath, Bath U.K.
Tajaddini, A., Ibell, T. J., Darby, A. P., and Evernden, M. (2013). “A parametric study on moment redistribution in FRP-strengthened continuous RC beams.” 11th Int. Symp. on Fibre Reinforced Polymer for Reinforced Concrete Structures (FRPRCS-11), 2013: Conf. Proc., Univ. of Minho, Guimaraes, Portugal, 203–204.
Teng, J. G., Chen, J. F., Smith, S. T., and Lam, L. (2001). FRP strengthened RC structures, Wiley, New York.
Yost, J. R., Gross, S. P., Dinehart, D. W., and Mildenberg, J. J. (2007). “Flexural behavior of concrete beams strengthened with near-surface-mounted CFRP strips.” ACI Struct. J., 104(4), 430–437.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 21 • Issue 1 • February 2017
Copyright
© 2016 American Society of Civil Engineers.
History
Received: Jan 29, 2016
Accepted: Apr 13, 2016
Published online: Jun 30, 2016
Discussion open until: Nov 30, 2016
Published in print: Feb 1, 2017
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.