Design provisions for crack spacing and width in RC elements externally bonded with FRP

Verification of serviceability is a key issue in reinforced concrete (RC) elements; for RC elements externally bonded with fibre reinforced plastic (FRP) laminates and sheets cracking phenomena are usually verified by adopting the same approach used for steel RC elements. The available code provisions for crack width and spacing in steel RC elements are reviewed in this paper in order to ascertain the reliability of their application to RC elements strengthened with FRP sheets. Experimental results belonging to test programmes performed by the authors and other researchers on RC elements externally bonded with FRP were compared with existing code provisions in terms of crack width and spacing.A new formula for crack spacing, calibrated on the experimental results, is proposed for use in the expression given by the published version of EC2 for calculating crack width in RC elements externally bonded with FRP.