Polyurethane-FRP External Strengthening of RC Beams with No Steel Stirrups

AbstractExternally bonded (EB) fiber-reinforced polymer (FRP) composites are an effective means for the strengthening of shear-deficient reinforced concrete flexural members. Previous studies have predominantly employed epoxy-based wet layup systems. In this study, carbon FRP preimpregnated with pol...

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Bibliographic Details
Published in:Journal of composites for construction 2019-02, Vol.23 (1)
Main Authors: Al-Lebban, Yasir F, Mackie, Kevin R
Format: Article
Language:English
Subjects:
Beams (structural)
Bonding strength
Carbon fiber reinforced plastics
Epoxy resins
Fiber composites
Fiber reinforced polymers
Limit analysis
Mathematical models
Polymer matrix composites
Polyurethane resins
Preimpregnation
Reinforced concrete
Reinforcing steels
Shear
Size effects
Stirrups
Technical Papers
Upper bounds
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Summary:AbstractExternally bonded (EB) fiber-reinforced polymer (FRP) composites are an effective means for the strengthening of shear-deficient reinforced concrete flexural members. Previous studies have predominantly employed epoxy-based wet layup systems. In this study, carbon FRP preimpregnated with polyurethane resin is utilized in strengthening shear-deficient RC beams and compared with an epoxy resin. Fourteen small-scale (2,438×152×305  mm) and five large-scale (3,353×305×432  mm) flexural specimens were tested, considering FRP type (polyurethane, epoxy), size effect, shear span-to-depth ratio, FRP configuration (U-wraps, side bonding), and FRP scheme (sheets, strips at 45° or 90°). Four-point loading tests demonstrated similar or enhanced shear capacity for the polyurethane-strengthened RC beams compared to the epoxy-strengthened beams. A mechanics-based analytical model, utilizing the principle of effective FRP stress and the upper-bound theorem of limit analysis, illustrated that the shear behavior and debonding mechanism were dependent on both FRP composite and bond characteristics.
ISSN:1090-0268
1943-5614
DOI:10.1061/(ASCE)CC.1943-5614.0000916