Design equations for shear capacity of concrete girders strengthened in shear with externally bonded FRP sheets

Abdeldjelil Belarbi, Daniel Kuchma, Ayman Okeil, Sang Wook Bae

Research output: Contribution to conferencePaperpeer-review

2 Scopus citations


External strengthening with FRP is generally used for flexural strengthening, confinement, and improvement of ductility in columns or shear strengthening. While flexure is typically the limiting mode of failure in bridge girder design, shear failure may dominate in cases where the original transverse reinforcement has been severely corroded or the flexural strength has increased due to flexural strengthening. In such cases, the shear capacity should be enhanced to preclude shear failures which can be catastrophic. Though there has been a significant amount of research conducted on flexural and axial strengthening, the use of externally bonded FRP for shear strengthening has not been investigated as extensively. Despite limited experimental research, many models have been proposed for predicting the shear contribution of externally bonded FRP. These models are diverse in their approach and, in many cases, contradictory in their estimates of strength increase. This study was conducted as part of NCHRP 12-75 project to develop design equations and provisions. To achieve the goal of this study, a total of 49 published experimental studies containing more than 500 test results were reviewed and compiled into a database format. With this database, not only the performance of existing analytical models and design equations were evaluated, but also the parameters affecting the shear behavior of concrete girders strengthened in shear with FRP were identified. Finally, new and improved design equations were proposed in this study, and a reliability analysis was performed on the proposed design equations, using procedures similar to those in the calibration of AASHTO LRFD Bridge Design Specifications. The reliability analysis showed that the reliability indexes of the proposed design equations are nearly the same for all girder spacing and is about 3.5 for shorter span lengths but decreases for longer spans.

Original languageEnglish
StatePublished - Jan 1 2012
Event3rd Asia-Pacific Conference on FRP in Structures, APFIS 2012 - Sapporo, Japan
Duration: Feb 2 2012Feb 4 2012


Conference3rd Asia-Pacific Conference on FRP in Structures, APFIS 2012


  • Design equations
  • FRP
  • Shear
  • Strengthening
  • T-beam


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