American Society of Civil Engineers

Shear Strengthening of RC Beams with Externally Bonded FRP Composites: Effect of Strip-Width-to-Strip-Spacing Ratio

by Amir Mofidi, (Ph.D. Candidate, Dept. of Construction Engineering, Univ. of Quebec, École de Technologie Supérieure, Montreal QC, Canada H3C 1K3. E-mail: and Omar Chaallal, (corresponding author), M.ASCE, (Professor of Construction Engineering, Univ. of Quebec, École de Technologie Supérieure, 1100 Notre-Dame St. West, Montreal QC, Canada H3C 1K3. E-mail:

Journal of Composites for Construction, Vol. 15, No. 5, September/October 2011, pp. 732-742, (doi:

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Document type: Journal Paper
Abstract: The results of an experimental and analytical investigation of shear strengthening of reinforced concrete (RC) beams with externally bonded (EB) fiber-reinforced polymer (FRP) strips and sheets are presented, with emphasis on the effect of the strip-width-to-strip-spacing ratio on the contribution of FRP (Vf). In all, 14 tests were performed on 4,520-mm-long T-beams. RC beams strengthened in shear using carbon FRP (CFRP) strips with different width-to-spacing ratios were considered, and their performance was investigated. In addition, these results are compared with those obtained for RC beams strengthened with various numbers of layers of continuous CFRP sheet. Moreover, various existing equations that express the effect of FRP strip width and concrete-member width and that have been proposed based on single or double FRP-to-concrete direct pullout tests are checked for RC beams strengthened in shear with CFRP strips. The objectives of this study are to investigate the following: (1) the effectiveness of EB discontinuous FRP sheets (FRP strips) compared with that of EB continuous FRP sheets; (2) the optimum strip-width-to-strip-spacing ratio for FRP (i.e., the optimum FRP rigidity); (3) the effect of FRP strip location with respect to internal transverse-steel location; (4) the effect of FRP strip width; and (5) the effect of internal transverse-steel reinforcement on the CFRP shear contribution.

ASCE Subject Headings:
Fiber reinforced polymer
Concrete beams
Reinforced concrete
Shear strength

Author Keywords:
Carbon-fiber-reinforced polymers
Concrete beams
Continuous sheet
Discontinuous sheet
Shear strengthening
Strip-width-to-strip-spacing ratio