CFRP Repair and Strengthening of Structurally Deficient Piles: Design Issues and Field Application

The application of carbon fiber reinforced polymers (CFRP) for the repair and strengthening of corrosion-damaged elements is relatively recent. Although several demonstration studies have been completed, no formal design method is available. This paper presents analyses developed for the repair and rehabilitation of four square prestressed piles exposed to an aggressive marine environment. The analysis considers both loss in strength and corrosion-induced expansion. Strength restoration is obtained from interaction relations using a strain compatibility analysis. The longitudinal fibers of the bidirectional FRP layer configuration were designed to restore the strength; whereas, the transverse fibers were verified that they provide the necessary confinement to withstand expansive strains caused by corrosion. Three models proposed by Caltrans, ISIS, and the writers are compared. The Caltrans model is found to be the most conservative. The ISIS and the writers’ model gave similar results. A field demonstration was carried out in which segments of four prestressed piles located in the splash zone supporting the Allen Creek Bridge in Clearwater, Fla., were wrapped. Two of these piles are instrumented for continuous monitoring of their corrosion performance.