Numerical Analysis of RC Bridge Piers with Rectangular Hollow Cross-Section Retrofitted with FRP Jackets

Abstract

The research presented in this paper deals with the seismic retrofit of bridge piers with rectangular hollow cross-section using fibre-reinforced polymer (FRP) jackets. A two-level numerical approach that combines finite element method (FEM) analyses and fibre modelling is proposed. The FEM is used to study the effect of FRP jackets on the properties of concrete. The analyses show that the existing empirical laws for FRP-confined concrete are not suitable for piers with hollow cross-section, as the effect of confinement is not uniform within the cross-section and the stress–strain curves show softening after peak strength. Fibre modelling is used to study the global behaviour of reinforced concrete piers with rectangular hollow cross-section wrapped with FRP jackets. To account for confinement, the properties of the concrete fibres are modified according to the results of the FEM analyses. The proposed method is validated against experimental results and used for an extensive parametric study. It is found that the effectiveness of jacketing is conditioned by the axial load, longitudinal reinforcement and jacket dimensions. An empirical design equation is formulated on the basis of the numerical analyses.