Retrofitting of bridge abutment timber piles using fiber-reinforced polymer composites

Abstract

Fiber-reinforced polymer (FRP) composites offer a versatile and effective retrofitting option for deteriorated bridge timber piles. Although full confinement using FRP is not feasible for abutment piles, reinforcing the tension side of the pile can effectively improve the stiffness and strength of abutment piles. In this study, three full-scale timber piles are tested. Nondestructive stress wave timing methods are used to assess the initial condition of the piles and two inferior specimens are retrofitted with Glass-FRP (GFRP) composites in different configurations. To simulate typical loading on abutment piles, a unique test set-up is developed to apply a bending moment through eccentric loading. Test results show that a reliable estimate of the existing timber pile material properties is in order to design effective FRP retrofits. Using timber pile material models calibrated using the experimental results, a finite element (FE) model of the test set-up is developed to investigate FRP retrofit design requirements. Finite element analysis shows that the retrofit methods used in the experimental study are highly effective especially under high-bending moments. However, the FRP configuration and amount of FRP required must be determined based on the timber pile condition.