Innovative CFRP-Prestressing System for Strengthening Metallic Structures
Publication: Journal of Composites for Construction
Volume 19, Issue 6
Abstract
An innovative retrofit system to prestress carbon fiber reinforced polymer (CFRP) plates and attach them to existing metallic beams was developed (patent number CH 706 630 B1) and tested. The system does not require any glue between the CFRP plates and the beams; therefore, surface preparation is not necessary, which reduces the time and cost of retrofitting. The proposed prestressed unbonded reinforcement (PUR) system includes a pair of mechanical clamps that function based on friction. Each clamp can simultaneously hold and attach three CFRP plates to the beam. The design considerations of the clamps, which are the most important elements of the PUR system, were explained. The system has a trapezoidal configuration that offers an easy on-site installation and uninstallation procedures without residual damage on the metallic beam. Three 5-m-long steel beams were statically tested until failure, including one reference unstrengthened beam and two beams that were strengthened with 15% and 31% CFRP prestress levels. A considerable increase in the yielding and ultimate load capacities of the retrofitted beams was achieved. The ultimate load-carrying capacity of the strengthened beams with 15% and 31% CFRP prestress levels increased by more than 23% and 31%, respectively, compared to that of the reference specimen. A finite-element (FE) model was created to simulate the behavior of the retrofitted beams. Next, the FE results were compared with those from the experiments.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
This study was funded by the Swiss Commission of Technology and Innovation (CTI) (Grant No. 12993.1 PFIW-IW). Financial and technological support from the S&P Clever Reinforcement AG Company, and the Swiss Federal Railways (SBB) are also acknowledged. Furthermore, the authors would like to thank Dr. A. Herwig, Prof. A. Nussbaumer from EPFL, Lausanne, and Prof. M. Fontana from ETH, Zürich, for their helps in this study. Thanks also go to the technicians of the Structural Engineering Research Laboratory of Empa for their excellent collaboration in performing the experiments.
References
ABAQUS standard user’s manual, version 6.4. (2012). Hibbitt, Karlsson, and Sorensen, Pawtucket, RI.
Al-Emrani, M., and Kliger, R. (2006a). “Analysis of interfacial shear stresses in beams strengthened with bonded prestressed laminates.” Compos. Part B, 37(4–5), 265–272.
Al-Emrani, M., and Kliger, R. (2006b). “Experimental and numerical investigation of the behaviour and strength of composite steel-CFRP members.” Adv. Struct. Eng., 9(6), 819–831.
Benachour, A., Benyoucef, S., Tounsi, A., and Adda Bedia, E. A. (2008). “Interfacial stress analysis of steel beams reinforced with bonded prestressed plates.” Eng. Struct., 30(11), 3305–3315.
Bien, J., Elfgren, L., and Olofsson, J. (2007). Sustainable bridges, assessment for future traffic demands and longer lives, Dolnoslaskie Wydawnictwo Edukacyjne, Wrocław, Poland.
Colombi, P., Bassetti, A., and Nussbaumer, A. (2003). “Crack growth induced delamination on steel members reinforced by prestressed composite patch.” Fatigue Fract. Eng. Mater. Struct., 26(5), 429–437.
Czaderski, C., and Rabinovitch, O. (2010). “Structural behavior and inter-layer displacements in CFRP plated steel beams—Optical measurements, analysis, and comparative verification.” Compos. Part B, 41(4), 276–286.
Dawood, M., and Rizkalla, S. (2010). “Environmental durability of a CFRP system for strengthening steel structures.” Constr. Build. Mater., 24(9), 1682–1689.
Fernando, D., Schumacher, A., Motavalli, M., Teng, J. G., Yu, T., and Ghafoori, E. (2010). “Fatigue strengthening of cracked steel beams with CFRP plates.” ASME Int. Mechanical Engineering Congress and Exposition, Proc., (IMECE), Vol. 9, ASME, 271–276.
Fernando, N. D. (2010). “Bond behaviour and debonding failures in CFRP-strengthened steel members.” Ph.D. thesis, Hong Kong Polytechnic Univ., Hong Kong.
Ghafoori, E. (2012). “Interfacial stresses in beams strengthened with bonded prestressed plates.” Eng. Struct., 46, 508–510.
Ghafoori, E., et al. (2014). “Finite element analysis for fatigue damage reduction in metallic riveted bridges using pre-stressed CFRP plates.” Polymers, 6(4), 1096–1118.
Ghafoori, E., and Motavalli, M. (2011). “Analytical calculation of stress intensity factor of cracked steel I-beams with experimental analysis and 3D digital image correlation measurements.” Eng. Fract. Mech., 78(18), 3226–3242.
Ghafoori, E., and Motavalli, M. (2013a). “Flexural and interfacial behavior of metallic beams strengthened by prestressed bonded plates.” Compos. Struct., 101, 22–34.
Ghafoori, E., and Motavalli, M. (2013b). “Method for the pre-tensioning of steel constructions.” Swiss Patent, CH 706 630 B1.
Ghafoori, E., and Motavalli, M. (2015a). “Lateral-torsional buckling of steel I-beams retrofitted by bonded and un-bonded CFRP laminates with different pre-stress levels: Experimental and numerical study.” Constr. Build. Mater, 76, 194–206.
Ghafoori, E., and Motavalli, M. (2015b). “Normal, high and ultra-high modulus CFRP laminates for bonded and un-bonded strengthen-ing of steel beams.” Mater. Des., 67, 232–243.
Ghafoori, E., Motavalli, M., Botsis, J., Herwig, A., and Galli, M. (2012a). “Fatigue strengthening of damaged metallic beams using prestressed unbonded and bonded CFRP plates.” Int. J. Fatigue, 44, 303–315.
Ghafoori, E., Motavalli, M., Nussbaumer, A., Herwig, A., Prinz, G., and Fontana, M. (2015a). “Determination of minimum CFRP pre-stress levels for fatigue crack prevention in retrofitted metallic beams.” Eng. Struct., 84, 29–41.
Ghafoori, E., Motavalli, M., Nussbaumer, A., Herwig, A., Prinz, G. S., and Fontana, M. (2015b). “Design criterion for fatigue strengthening of riveted beams in a 120-year-old railway metallic bridge using pre-stressed CFRP plates.” Compos. Part B, 68, 1–13.
Ghafoori, E., Schumacher, A., and Motavalli, M. (2012b). “Fatigue behavior of notched steel beams reinforced with bonded CFRP plates: Determination of prestressing level for crack arrest.” Eng. Struct., 45, 270–283.
Haghani, R., Al-Emrani, M., and Kliger, R. (2009). “Interfacial stress analysis of geometrically modified adhesive joints in steel beams strengthened with FRP laminates.” Constr. Build. Mater., 23(3), 1413–1422.
Huawen, Y., König, C., Ummenhofer, T., Shizhong, Q., and Plum, R. (2010). “Fatigue performance of tension steel plates strengthened with prestressed CFRP laminates.” J. Compos. Constr., 609–615.
Kerboua, B., Adda Bedia, E. A., and Benmoussat, A. (2011). “Strengthening of damaged structures with bonded prestressed FRP composite plates: An improved theoretical solution.” J. Compos. Mater., 45(5), 499–512.
Linghoff, D., Al-Emrani, M., and Kliger, R. (2010). “Performance of steel beams strengthened with CFRP laminate—Part 1: Laboratory tests.” Compos. Part B, 41(7), 509–515.
Phares, B. M., Wipf, T. J., Klaiber, F. W., Abu-Hawash, A., and Lee, Y. S. (2003). “Strengthening of steel girder bridges using FRP.” Proc., 2003 Mid-Continent Transportation Research Symp., Iowa State Univ., Ames, IA.
Rizkalla, S., Dawood, M., and Schnerch, D. (2008). “Development of a carbon fiber reinforced polymer system for strengthening steel structures.” Compos. Part A, 39(2), 388–397.
Schnerch, D., and Rizkalla, S. (2008). “Flexural strengthening of steel bridges with high modulus CFRP strips.” J. Bridge Eng., 192–201.
Smith, S. T., and Teng, J. G. (2001). “Interfacial stresses in plated beams.” Eng. Struct., 23(7), 851–871.
Täljsten, B., Hansen, C. S., and Schmidt, J. W. (2009). “Strengthening of old metallic structures in fatigue with prestressed and non-prestressed CFRP laminates.” Constr. Build. Mater., 23(4), 1665–1677.
Wang, R., and Nussbaumer, A. (2009). “Modelling fatigue crack propagation of a cracked metallic member reinforced by composite patches.” Eng. Fract. Mech., 76(9), 1277–1287.
Wu, C., Zhao, X. L., Al-Mahaidi, R., Emdad, M. R., and Duan, W. H. (2013a). “Fatigue tests on steel plates with longitudinal weld attachment strengthened by ultra high modulus carbon fibre reinforced polymer plate.” Fatigue Fract. Eng. Mater. Struct., 36(10), 1027–1038.
Wu, C., Zhao, X. L., Chiu, W. K., Al-Mahaidi, R., and Duan, W. H. (2013b). “Effect of fatigue loading on the bond behaviour between UHM CFRP plates and steel plates.” Composites Part B, 50, 344–353.
Zhao, X. L. (2013). FRP-strengthened metallic structures, Taylor and Francis, Boca Raton, FL.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 19 • Issue 6 • December 2015
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Jun 10, 2014
Accepted: Dec 8, 2014
Published online: Jan 20, 2015
Discussion open until: Jun 20, 2015
Published in print: Dec 1, 2015
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.