Prediction of Interface Shear Stresses in Elastoplastic Moment-Varying Zones of Advanced Composite Material-Strengthened Concrete Members
Publication: Journal of Structural Engineering
Volume 128, Issue 9
Abstract
Adhesive bonding of plates of advanced composite materials (ACMs) to reinforced concrete structural members is increasingly used to strengthen such members in flexure. The integrity of the strengthened member under load depends on the level of hybrid structural action developed between the concrete member and the plate through the adhesive. High shear stresses at the adhesive-to-concrete interface trigger fracture of the concrete, and so induce failure by loss of this hybrid action. In zones of varying moment along the member, these high interface shear stresses can arise from the requirement, after the steel yields, for high axial stress gradients to develop in the ACM plate. In these moment-varying zones of elastoplastic activity, the steel and concrete are into their nonlinear regimes of material behavior, and the height of the neutral axis changes nonlinearly along the member. These nonlinear effects, which generate complex behavior in elastoplastic zones, are not represented in existing approaches for predicting interface shear stresses. This paper fills that gap by presenting analytically exact expressions for interface shear stress which allow for vertical shift of the neutral axis and for material nonlinearities. The expressions reveal that distinct nonlinear disparities exist between the interface shear stress variations and the shear force variations in moment-varying elastoplastic zones. The model is verified against test data, and is then used to establish magnitudes of elastoplastic interface shear stress in a plated member under different types of load. The stresses are shown to reach critical values, and their variations along the plated member are seen to be load sensitive. It is concluded that this model for elastoplastic interface shear stresses is suitable for incorporation into procedures for design of ACM-strengthening schemes.
Get full access to this article
View all available purchase options and get full access to this article.
References
Arduini, M., and Nanni, A.(1997). “Behavior of precracked RC beams strengthened with carbon FRP sheets.” J. Compos. Constr., 1(2), 63–70.
Arya, C., and Farmer, N. (2001). “Design guidelines for flexural strengthening of concrete members using FRP composites.” Proc., FRPRCS-5 Conf., Cambridge, U.K., Vol. 1, C. J. Burgoyne, ed., Telford, London, 167–176.
Blaschko, M., Niedermeier, R., and Zilch, K. (1998). “Bond failure modes of flexural members strengthened with FRP.” Proc., 2nd Int. Conf. on Compos. in Infr., Tucson, Ariz., Vol. 1, H. Saadatmanesh and M. Ehsani, ed., 315–327.
Kim, D., and and Sebastian, W. M.(2002). “Parametric study of bond failure in concrete beams externally strengthened with fibre reinforced polymer plates.” Mag. Conc. Res., Telford, London, 54(1), 47–59.
Kishi, N., Mikami, H., Matsuoka, K., and Kurihashi, Y. (2001). “Failure of strengthened RC beams with AFRP sheets.” Proc., FRPRCS-5 Conf., Cambridge, England, Vol. 1, C. J. Burgoyne, ed., Telford, London, 87–95.
Malek, A. M., Saadatmanesh, H., and Ehsani, M. R.(1998). “Prediction of failure loads of R/C beams strengthened with FRP plate due to stress concentration at plate end.” ACI Struct. J., 95(1), 142–152.
Oehlers, D. J., and Moran, J. P.(1990). “Premature failure of externally plated reinforced concrete beams.” J. Struct. Eng., 116(4), 978–995.
Rabinovitch, O., and Frostig, Y.(2001), “High-order approach for the control of edge stresses in RC beams strengthened with FRP strips.” J. Struct. Eng., 127(7), 799–809.
Rahimi, H., and Hutchinson, A.(2001). “Concrete beams strengthened with externally bonded FRP plates.” J. Compos. Constr., 5(1), 44–56.
Sebastian, W. M.(2001). “Significance of midspan debonding failure in FRP-plated concrete beams.” J. Struct. Eng., 127(7), 792–798.
Sebastian, W. M.(2002). “Sensitivities of strength and ductility of plated reinforced concrete sections to preexisting strains.” J. Struct. Eng., 128(5), 624–636.
Swamy, R. N., and Mukhopadhyaya, P. (1999). “Debonding of carbon fibre-reinforced polymer plate from concrete beams.” Proc., Inst. Civil Eng. Struct. Build., 134, 301–317.
Täljsten, B. (1994). “Plate bonding: Strengthening of existing concrete structures with epoxy bonded plates of steel or fibre reinforced plastics.” Doctoral thesis, Lulea Univ. of Technology, Sweden.
Triantafillou, T. C., and Plevris, N.(1992). “Strengthening of RC beams with epoxy-bonded fibre composite materials.” Mater. Struct., 25, 201–211.
Varastehpour, H., and Hamelin, P. (1996). “Analysis and study of failure mechanism of RC beams strengthened with FRP plate.” Proc., 2nd Int. Conf. on Advanced Composite Materials in Bridges and Structures, Paris, Vol. 25, 201–211.
Information & Authors
Information
Published In
Copyright
Copyright © 2002 American Society of Civil Engineers.
History
Received: Jan 24, 2001
Accepted: Mar 22, 2002
Published online: Aug 15, 2002
Published in print: Sep 2002
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.