Interaction between Steel Stirrups and Shear-Strengthening FRP Strips in RC Beams
Publication: Journal of Composites for Construction
Volume 14, Issue 5
Abstract
RC beams shear strengthened with either fiber-reinforced polymer (FRP) U-jackets/U-strips or side strips commonly fail due to debonding of the bonded FRP shear reinforcement. As such debonding occurs in a brittle manner at relatively small shear crack widths, some of the internal steel stirrups may not have reached yielding. Consequently, the yield strength of internal steel stirrups in such a strengthened RC beam cannot be fully used. In this paper, a computational model for shear interaction between FRP strips and steel stirrups is first presented, in which a general parabolic crack shape function is employed to represent the widening process of a single major shear crack in an RC beam. In addition, appropriate bond-slip relationships are adopted to accurately depict the bond behavior of FRP strips and steel stirrups. Numerical results obtained using this computational model show that a substantial adverse effect of shear interaction generally exists between steel stirrups and FRP strips for RC beams shear strengthened with FRP side strips. For RC beams shear strengthened with FRP U-strips, shear interaction can still have a significant adverse effect when FRP strips with a high axial stiffness are used. Therefore, for accurate evaluation of the shear resistance of RC beams shear strengthened with FRP strips, this adverse effect of shear interaction should be properly considered in design.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The writers are grateful for the financial support received from the Research Grants Council of the Hong Kong Special Administrative Region (Project No: UNSPECIFIEDPolyU 5151/03E) and The Hong Kong Polytechnic University (Project Code: UNSPECIFIEDBBZH). They would also like to acknowledge the support from the Scottish Funding Council for the Joint Research Institute between the University of Edinburgh and Heriot-Watt University which forms part of the Edinburgh Research Partnership in Engineering and Mathematics (ERPem).
References
ABAQUS, Inc. (2004). “ABAQUS 6.5.” ABAQUS user’s manual, Providence, R.I.
Bousselham, A., and Chaallal, O. (2004). “Shear strengthening reinforced concrete beams with fiber-reinforced polymer: Assessment of influencing parameters and required research.” ACI Struct. J., 101(2), 219–227.
Bousselham, A., and Chaallal, O. (2006a). “Behavior of RC T beams strengthened in shear with CFRP: An experimental study.” ACI Struct. J., 103(3), 339–347.
Bousselham, A., and Chaallal, O. (2006b). “Effect of transverse steel and shear span on the performance of RC beams strengthened in shear with CFRP.” Composites, Part B, 37(1), 37–46.
Bousselham, A., and Chaallal, O. (2008). “Mechanisms of shear resistance of concrete beams strengthened in shear with externally bonded FRP.” J. Compos. Constr., 12(5), 499–512.
Carolin, A., and Taljsten, B. (2005). “Experimental study of strengthening for increased shear bearing capacity.” J. Compos. Constr., 9(6), 488–496.
Chen, G. M. (2010). “Shear behaviour and strength of RC beams shear-strengthened with externally bonded FRP reinforcement.” Ph.D. thesis, Dept. of Civil and Structural Engineering, Hong Kong Polytechnic Univ., Hong Kong.
Chen, G. M., Teng, J. G., and Chen, J. F. (2010). “RC beams shear-strengthened with FRP: Shear resistance contributed by externally bonded FRP reinforcement.” Mag. Concrete Res., 62(4), 301–311.
Chen, J. F., and Teng, J. G. (2001). “Anchorage strength models for FRP and steel plates bonded to concrete.” J. Struct. Eng., 127(7), 784–791.
Chen, J. F., and Teng, J. G. (2003a). “Shear capacity of FRP-strengthened RC beams: FRP debonding.” Constr. Build. Mater., 17(1), 27–41.
Chen, J. F., and Teng, J. G. (2003b). “Shear capacity of FRP strengthened RC beams: Fibre reinforced polymer rupture.” J. Struct. Eng., 129(5), 615–625.
Chen, J. F., Yuan, H., and Teng, J. G. (2007). “Debonding failure along a softening FRP-to-concrete interface between two adjacent cracks in concrete members.” Eng. Struct., 29(2), 259–270.
China Architecture & Building. (2002). “Code for design of concrete structures.” GB-50010, Beijing (in Chinese).
Comite Euro-International du Beton-Federation International de la Precontrainte (CEB-FIP). (1993). CEB-FIP model code 1990, Thomas Telford, London.
Diagana, C., Li, A., Gedalia, B., and Delmas, Y. (2003). “Shear strengthening effectiveness with CFF strips.” Eng. Struct., 25(4), 507–516.
Khalifa, A., and Nanni, A. (2002). “Rehabilitation of rectangular simply supported RC beams with shear deficiencies using CFRP composites.” Construct. Build. Mater., 16(3), 135–146.
Li, A., Diagana, C., and Delmas, Y. (2001). “CRFP contribution to shear capacity of strengthened RC beams.” Eng. Struct., 23(10), 1212–1220.
Li, A., Diagana, C., and Delmas, Y. (2002). “Shear strengthening effect by bonded composite fabrics on RC beams.” Composites, Part B, 33(3), 225–239.
Lu, X. Z., Teng, J. G., Ye, L. P., and Jiang, J. J. (2005). “Bond-slip models for FRP sheets/plates bonded to concrete.” Eng. Struct., 27(6), 920–937.
Mohamed Ali, M. S., Oehlers, D. J., and Seracino, R. (2006). “Vertical shear interaction model between external FRP transverse plates and internal steel stirrups.” Eng. Struct., 28, 381–389.
Monti, G., and Liotta, M. A. (2007). “Tests and design equations for FRP-strengthening in shear.” Constr. Build. Mater., 21(4), 799–809.
Oehlers, D. J., Mohamed Ali, M. S., and Seracino, R. (2005). “Vertical shear partial interaction modelling of transversely plated RC members with steel stirrups.” Proc., Int. Symp. on Bond Behavior of FRP in Structures, International Institute for FRP in Construction (IIFC), Hong Kong, 357–362.
Pellegrino, C., and Modena, C. (2002). “Fiber reinforced polymer shear strengthening of RC beams with transverse steel reinforcement.” J. Compos. Constr., 6(2), 104–111.
Pellegrino, C., and Modena, C. (2006). “Fiber-reinforced polymer shear strengthening of reinforced concrete beams: Experimental study and analytical modeling.” ACI Struct. J., 103(5), 720–728.
Teng, J. G., Chen, G. M., Chen, J. F., Rosenboom, O. A., and Lam, L. (2009). “Behavior of RC beams shear strengthened with bonded or unbonded FRP wraps.” J. Compos. Constr., 13(5), 394–404.
Teng, J. G., and Chen, J. F. (2009). “Mechanics of debonding in FRP-plated RC beams.” Proc. Inst. Civ. Eng., Struct. Build., 162(5), 335–345.
Teng, J. G., Chen, J. F., and Smith, S. T. (2008). “Design guidelines for fibre-reinforced polymer (FRP)-strengthened reinforced concrete (RC) structures.” Strengthening and rehabilitation of civil infrastructures using fibre-reinforced polymer (FRP) composites, Chap. 8, Woodhead Publishing, Cambridge, U.K., 195–214.
Teng, J. G., Chen, J. F., Smith, S. T., and Lam, L. (2002). FRP-strengthened RC structures, Wiley, Chichester, U.K.
Teng, J. G., Lam, L., and Chen, J. F. (2004). “Shear strengthening of RC beams using FRP composites.” Prog. Struct. Eng. Mater., 6, 173–184.
Teng, J. G., Yuan, H., and Chen, J. F. (2006). “FRP-to-concrete interfaces between two adjacent cracks: Theoretical model for debonding failure.” Int. J. Solids Struct., 43(18–19), 5750–5778.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 14 • Issue 5 • October 2010
Pages: 498 - 509
Copyright
© 2010 ASCE.
History
Received: Jul 31, 2009
Accepted: Mar 11, 2010
Published online: Mar 16, 2010
Published in print: Oct 2010
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.