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Rectangular reinforced concrete beams strengthened with CFRP straps


Type

Article

Change log

Authors

Yapa, HD 
Lees, JM 

Abstract

Shear deficient reinforced concrete (RC) structures can be effectively strengthened using external prestressed carbon fibre reinforced polymer (CFRP) straps. Due to the presence of the external elastic straps, a strengthened beam can continue to carry significant load beyond the stages of crack plane slipping and internal shear stirrup yielding, and the concrete is subjected to high tensile strain levels. As a consequence, the concrete material models play a significant role in the context of modeling such behavior. The modified compression field theory (MCFT), which is a widely accepted shear theory for unstrengthened RC structures, incorporates the details of the stress-strain behavior of concrete. The MCFT also considers compatibility as a governing factor, which facilitates the inclusion of the strap system into the MCFT formulation. In the current study, modifications were investigated to model CFRP strap retrofitted RC beams associated with either uniform or non-uniform strap spacings. An experimental investigation on strengthened and unstrengthened rectangular RC beams was carried out to validate the MCFT predictions for various strap layouts. The validation process revealed that, in general, the MCFT was able to model the shear response of the retrofitted RC beams but the representation of the softening of the concrete compressive strain, and stress, was found to be influential in the determination of the ultimate load capacity.

Description

Keywords

Shear strengthening, Reinforced concrete (RC) beams, Carbon fiber-reinforced polymer (CFRP) straps, Modified compression field theory (MCFT)

Journal Title

Journal of Composites for Construction

Conference Name

Journal ISSN

1090-0268
1943-5614

Volume Title

Publisher

American Society of Civil Engineers (ASCE)
Sponsorship
Engineering and Physical Sciences Research Council (EP/J002887/1)
Cambridge Commonwealth Trust; Overseas Research Studentship; Churchill College.