Theoretical Model and Computational Procedure to Evaluate the NSM FRP Strips Shear Strength Contribution to a RC Beam
Publication: Journal of Structural Engineering
Volume 137, Issue 11
Abstract
This paper presents a computational procedure to evaluate the shear strength contribution provided to a reinforced concrete (RC) beam by a system of near-surface mounted (NSM) fiber reinforced polymer (FRP) strips. This procedure is based on the evaluation of (1) the constitutive law of the average-available bond-length NSM FRP strip effectively crossing the shear crack, and (2) the maximum effective capacity it can attain during the loading process of the strengthened beam. Because of complex phenomena such as (1) interaction between forces transferred through bond to the surrounding concrete and the concrete fracture, and (2) interaction among adjacent strips, the NSM FRP strip constitutive law is largely different than the linear elastic one characterizing the FRP behavior in tension. Once the constitutive law of the average-available bond-length NSM strip is reliably known, its maximum effective capacity can be determined by imposing a coherent kinematic mechanism. The self-contained and ready-to-implement set of analytical equations and logical operations is presented along with the main underlying physical-mechanical principles and assumptions. The formulation proposed is appraised against some of the most recent experimental results, and its predictions are also compared with those obtained by a recently developed more sophisticated model.
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Acknowledgments
The authors of the present work wish to acknowledge the support provided by the “Empreiteiros Casais”, S&P, Degussa Portugal, and Secil (Unibetão, Braga). The study reported in this paper forms a part of the research program “CUTINEMO—Carbon fiber laminates applied according to the near surface mounted technique to increase the flexural resistance to negative moments of continuous reinforced concrete structures” supported by FCT, UNSPECIFIEDPTDC/ECM/73099/2006. Also, this work was carried out under the auspices of the Italian DPC-ReLuis Project (repertory n. 540), Research Line 8, whose financial support is greatly appreciated.
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Published In
Journal of Structural Engineering
Volume 137 • Issue 11 • November 2011
Pages: 1359 - 1372
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Jul 24, 2009
Accepted: Dec 27, 2010
Published online: Dec 29, 2010
Published in print: Nov 1, 2011
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