Bulletin 14: Externally Applied FRP Reinforcement for Concrete Structures (updated edition)
About this book
FIB (Fédération Internationale du Béton) Bulletin 14: Externally Applied FRP Reinforcement for Concrete Structures (Updated Knowledge Report), published by the fib (International Federation for Structural Concrete), is the primary international technical reference for the design, assessment, and installation of fibre reinforced polymer (FRP) composite systems applied externally to concrete structural members for strengthening and rehabilitation. This updated knowledge report consolidates research and practical experience accumulated since the original fib Bulletin 14 was published in 2001. Externally bonded FRP systems are used to increase the flexural capacity, shear resistance, and ductility of existing reinforced concrete beams, columns, slabs, and walls without the significant mass addition and formwork requirements of conventional concrete jacketing.
The primary FRP materials used are carbon fibre reinforced polymer (CFRP), glass fibre reinforced polymer (GFRP), and aramid fibre reinforced polymer (AFRP), applied as pre-cured laminates bonded with epoxy adhesive or as wet lay-up fabric systems laminated in situ. The bulletin presents the design framework for flexural strengthening: the plane sections analysis accounting for the strain compatibility between FRP reinforcement and the existing concrete cross-section, the limiting strain in the FRP at ultimate limit state (governed by debonding rather than fibre rupture in most practical cases), and the reduction factor approach to account for uncertainties in FRP mechanical properties and installation quality. Debonding failure modes — intermediate crack-induced debonding, concrete cover separation, plate end debonding — are analysed in detail and design rules are provided for each.
Shear strengthening configurations are covered: U-wrapping, full wrapping, and side bonding, with effectiveness depending on concrete confinement conditions and FRP fibre orientation. Column confinement applications — wrapping columns with circumferential FRP to increase compressive ductility — are treated separately, as the design approach for this application differs fundamentally from flexural strengthening. Durability, inspection, and monitoring provisions address the long-term performance of epoxy-bonded FRP systems under thermal cycling, moisture exposure, UV degradation, and fire.
The bulletin advocates for systematic inspection protocols and acoustic emission monitoring as tools for detecting debonding progression before it becomes structural failure.