Abstract
This work deals with the development of a mechanics-based shear model for reinforced concrete (RC) elements strengthened in shear with fiber-reinforced polymer (FRP) and a design/assessment procedure capable of predicting the failure sequence of resisting elements: the yielding of existing transverse steel ties and the debonding of FRP sheets/strips, while checking the corresponding compressive stress in concrete. The research aims at the definition of an accurate capacity equation, consistent with the requirement of the pseudo-ductile shear behavior of structural elements, that is, transverse steel ties yield before FRP debonding and concrete crushing. For the purpose of validating the proposed model, an extended parametric study and a comparison against experimental results have been conducted: it is proven that the common accepted rule of assuming the shear capacity of RC members strengthened in shear with FRP as the sum of the maximum contribution of both FRP and stirrups can lead to an unsafe overestimation of the shear capacity. This issue has been pointed out by some authors, when comparing experimental shear capacity values with the theoretical ones, but without giving a convincing explanation of that. In this sense, the proposed model represents also a valid instrument to better understand the mechanical behavior of FRP-RC beams in shear and to calculate their actual shear capacity.
Highlights
Shear capacity equations proposed by current codes for fiber-reinforced polymer reinforced concrete (FRP-RC) elements stem either from regression-based models, derived from experimental results available in the literature, or from simplified strut-and-tie models with an implicit application of the plasticity theory
Triantafillou and Antonopoulos [5] introduced a design model to evaluate the contribution of FRP to the shear capacity: it is based on the calculation of an effective FRP strain, obtained through calibration with experimental tests and defined as the minimum value among the maximum strain to control the crack opening, the strain corresponding to premature shear failure due to FRP debonding and the strain corresponding to shear failure combined with or followed by FRP tensile fracture
This work goes along the theoretical line traced by Monti and Liotta [6], whereby the stress state in an FRP-shear-strengthened reinforced concrete element is accurately followed, with particular reference to the transverse steel stirrups, the strengthening FRP sheet/strips and the concrete strut, by progressively widening a shear crack that crosses them
Summary
Shear capacity equations proposed by current codes for fiber-reinforced polymer reinforced concrete (FRP-RC) elements stem either from regression-based models, derived from experimental results available in the literature, or from simplified strut-and-tie models with an implicit application of the plasticity theory. Triantafillou and Antonopoulos [5] introduced a design model to evaluate the contribution of FRP to the shear capacity: it is based on the calculation of an effective FRP strain, obtained through calibration with experimental tests and defined as the minimum value among the maximum strain to control the crack opening, the strain corresponding to premature shear failure due to FRP debonding and the strain corresponding to shear failure combined with or followed by FRP tensile fracture Along this line of research, many models have been proposed, Chen and Teng [6], Carolin and Taljsten [7]. The proposed model allows predicting the failure sequence of the resisting elements while checking the stress of the concrete strut, but most of all, it allows for a better understanding of the underlying mechanical behavior determining the actual shear resistance of an RC member strengthened in shear with FRP
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
