Debonding Mitigation of CFRP-Strengthened Steel Beams with Silyl-Modified Polymer and CFRP Wrap Anchorage
Publication: Journal of Composites for Construction
Volume 19, Issue 1
Abstract
This paper presents an innovative strengthening methodology for damaged steel beams with carbon-fiber-reinforced polymer (CFRP) sheets. Emphasis is placed on controlling premature CFRP debonding using an emerging material called silyl-modified polymer (SMP) in conjunction with its hybrid bond application with a conventional epoxy adhesive. The hypothesis proposed is that the low-modulus SMP addresses stress singularity along the CFRP-steel interface, while the high-modulus epoxy preserves interfacial capacity. CFRP anchorage assists the efficacy of such a hybrid bond configuration. A two-phase experimental program is conducted to evaluate the performance of various CFRP-strengthening schemes, including element- and structural-level investigations (i.e., interface and beam tests, respectively). Test results reveal that the SMP bond mitigates CFRP debonding that is commonly observed in epoxy bond. The strengthening systems employed significantly improve the flexural behavior of the test beams in terms of ductility and failure characteristics.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The writers gratefully acknowledge support from Tri-college, Mid-America Steel, Bostik, and the U.S. Department of Transportation through the Mountain Plains Consortium Program. The experimental research has partly been conducted by Mr. A. Hmidan, and his initial effort is appreciated. The writers also thank Mr. E. Bodenstab for his editorial review and suggestions. The findings described here are those of the writers and do not necessarily represent the opinion of others.
References
American Concrete Institute (ACI). (2008). “Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures.” ACI-440.2R-08, Farmington Hills, MI.
American National Standards Institute (ANSI). (2007). “Testing of sealing materials for buildings—Part 1: Determination of change in mass and volume of self-leveling joint sealants.” DIN 52451, Washington, DC.
Bachir Bouiadjra, B., Fekirini, H., Belhouari, M., Boutabout, B., and Serier, B. (2007). “Fracture energy for repaired cracks with bonded composite patch having two adhesive bands in aircraft structures.” Comput. Mater. Sci., 40(1), 20–26.
BASF. (2007). “MBrace CF130 unidirectional high strength carbon fiber fabric for the MBrace composite strengthening system.” BASF Construction Chemicals, Shakopee, MN.
Bizindavyi, L., and Neale, K. W. (1999). “Transfer lengths and bond strengths for composites bonded to concrete.” J. Compos. Constr., 153–160.
Bostik. (2011). Bostik 70-03A data sheet, Middleton, MA.
da Silva, L. F. M., and Lopes, M. J. C. Q. (2009). “Joint strength optimization by the mixed-adhesive technique.” Int. J. Adhes. Adhes., 29(5), 509–514.
Di Bella, G., Galtieri, G., Pollicino, E., and Borsellino, C. (2013). “Mechanical characterization of adhesive joints with dissimilar substrates for marine applications.” Int. J. Adhes. Adhes., 41, 33–40.
Fitton, M. D., and Broughton, J. G. (2005). “Variable modulus adhesives: An approach to optimized joint performance.” Int. J. Adhes. Adhes., 25(4), 329–336.
Galal, K., ElDin, H. M. S., and Tirca, L. (2012). “Flexural performance of steel girders retrofitted using CFRP materials.” J. Compos. Constr., 265–276.
Green, M. F., Bisby, L. A., Beaudoin, Y., and Labossiere, P. (2000). “Effect of freeze-thaw cycles on the bond durability between fibre reinforced polymer plate reinforcement and concrete.” Can. J. Civ. Eng., 27(5), 949–959.
Hmidan, A., Kim, Y. J., and Yazdani, S. (2011). “CFRP repair of steel beams with various initial crack configurations.” J. Compos. Constr., 952–962.
Kim, Y. J., and Brunell, G. (2011). “Interaction between CFRP-repair and initial damage of wide-flange steel beams subjected to three-point bending.” Compos. Struct., 93(8), 1986–1996.
Kim, Y. J., and Harries, K. A. (2012). “Predictive response of notched steel beams repaired with CFRP strips including bond-slip behavior.” Int. J. Struct. Stab. Dyn., 12(1), 1–21.
Kim, Y. J., LaBere, J., and Yoshitake, I. (2013). “Hybrid epoxy-silyl modified polymer adhesives for CFRP sheets bonded to a steel substrate.” Compos. B Eng., 51, 233–245.
Kim, Y. J., Wight, R. G., and Green, M. F. (2008a). “Flexural strengthening of RC beams with prestressed CFRP sheets: Development of non-metallic anchor systems.” J. Compos. Constr., 35–43.
Kim, Y. J., Wight, R. G., and Green, M. F. (2008b). “Flexural strengthening of RC beams with prestressed CFRP sheets: Using non-metallic anchor systems.” J. Compos. Constr., 44–52.
Lenwari, A., Thepchatri, T., and Albrecht, P. (2006). “Debonding strength of steel beams strengthened with CFRP plates.” J. Compos. Constr., 69–78.
Mazzotti, C., Savois, M., and Ferracuti, B. (2008). “An experimental study on delamination of FRP plates bonded to concrete.” Constr. Build. Mater., 22(7), 1409–1421.
MBrace. (2003). “MBrace saturant: Epoxy encapsulation resin.” Watson Bowman Acme Corp., Amherst, NY.
Shaat, A., and Fam, A. (2008). “Repair of cracked steel girders connected to concrete slabs using carbon-fiber reinforced polymer sheets.” J. Compos. Constr., 650–659.
Smith, S. T., and Teng, J. G. (2001). “Interfacial stresses in plated beams.” Eng. Struct., 23(7), 857–871.
Tavakkolizadeh, M., and Saadatmanesh, H. (2003). “Repair of damaged steel-concrete composite girders using carbon fiber-reinforced polymer sheets.” J. Compos. Constr., 311–322.
Teng, J. G., Chen, J. F., Smith, S. T., and Lam, L. (2002). FRP strengthened RC structures, Wiley, West Sussex, England.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 19 • Issue 1 • February 2015
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Aug 5, 2013
Accepted: Feb 7, 2014
Published online: Mar 28, 2014
Discussion open until: Aug 28, 2014
Published in print: Feb 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.