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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Near-Surface-Mounted Fiber-Reinforced Polymer Reinforcements for Flexural Strengthening of Concrete Structures
Author(s): Raafat El-Hacha and Sami H. Rizkalla
Publication: Structural Journal
Appears on pages(s): 717-726
Keywords: bar; beam; carbon; concrete; fiber-reinforced polymer; glass; groove; strength; thermoplastic
Abstract:The use of fiber-reinforced polymer (FRP) materials for strengthening bridges and buildings has been used extensively in the last decade. FRP has been used in different configurations and techniques to use the material effectively and to ensure long service life of the selected system. One of these innovative strengthening techniques is the near-surface mounted (NSM) that consists of placing FRP reinforcing bars or strips into grooves precut into the concrete cover in the tension region of the strengthened concrete member. This method is relatively simple and considerably enhances the bond of the mounted FRP reinforcements, thereby using the material more effectively. This paper presents test results of reinforced concrete T-beams strengthened in flexure with different strengthening systems using FRP reinforcing bars and strips as NSM reinforcement and externally bonded FRP strips. The FRP reinforcements used in this investigation include carbon fiber-reinforced polymer (CFRP) reinforcing bars and strips and glass fiber-reinforced polymer (GFRP) thermoplastic strips. The behavior and effectiveness of the materials used for the various strengthening systems are compared. The structural performance and modes of failure of the tested beams are presented and discussed. Test results indicated that using NSM FRP reinforcing bars and strips is practical, significantly improves the stiffness, and increases the flexural capacity of reinforced concrete beams. The limitations of using NSM FRP reinforcing bars and strips are controlled by serviceability requirements in terms of overall deflections and crack widths rather than delamination, observed by many researchers, of externally bonded FRP reinforcement. Strengthening of reinforced concrete beams using NSM FRP strips provided higher strength capacity than externally bonded FRP strips using the same material with the same axial stiffness.
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