Confinement of RC Elements by Means of EBR FRP Systems

This chapter reviews the issues of confinement in plain and reinforced concrete under concentric compression and summarizes the state of the art regarding the available confinement models for strength and stress-strain behaviour of encased confined concrete, and the corresponding magnitude of dependable strain capacity. The mechanisms of confinement failure, the evolution of Poissons’ effects under low and high confinement, and the ensuing material compaction at high confining pressures (plastification) are discussed. The effects of stress concentrations near corners, the effectiveness of layers and influence of adhesive, other scale effects and the influence of specimen morphology on mechanical behaviour are also outlined. Next, the chapter concentrates on the effects of embedded reinforcement both longitudinal and transverse. Confinement effectiveness in the presence of combined flexure and shear (in plastic hinge regions), local effects due to rotation capacity increase, and effects of FRP confinement on overall member behaviour are discussed. Shape effects that occur in hollow or oblong sections are also considered. Furthermore, the chapter gives an outline regarding the characteristics of the international database of tests for confinement, and its calibration with the database of the available confinement models including those included in the design standards (ACI, CNR and EC8-III).