General behavior of t section RC beams strengthened with epoxy bonded carbon strands

摘要

Thereare no widely accepted guidelines for the design of concrete girdersstrengthened in shear using externally bonded FRP systems. The current researchintroduces the use of externally bonded CFRP strands to strengthen the beams inshear and increase its shear capacity, not in a U–shape form, but in a discreteform– on the sides only. Experimental behavior and test results of five T–sectionRC beams strengthened in shear are present. The main objectives of thisresearch are to evaluate, based on the experimental work, the impact of CFRPstrands amount per strip and spacing between strips on the shear behavior of RCbeams and to evaluate the applicability of existing analytical models of RCbeams strengthened in shear with CFRP Strands. The discrete strips of CFRPStrands are applied with different widths and spacing, bonded externally to thetest specimens in order to observe the overall behavior of the RC T–beams andthe mode of failure of the applied Carbon Strands strips. Results from theexperimental program shows that the application of Carbon Strands strips to RCT–beams did in fact enhance the overall behavior of the specimens. Thestrengthened specimens respond with an increase in shear capacity. The spacingbetween the CFRP strands should be less than half the effective depth of thestrengthened beam (d/2), and larger than the sum of width of the strengtheningstrip and the quarter of the effective depth of the specimen (W+d/4). Thegeometry of the CFRP strands allows full penetration of the epoxy through thestrengthening strips, which eliminates the deboning of the strips. The dominantmode of failure is cracking of the concrete cover under the CFRP strandsstrips, separating the strengthening strips from the specimens, followed byshear failure.