FRP Strengthening of Precast Prestressed Concrete Piles for Enhanced Integrity under Driving Impact

Abstract

In this study, a novel solution is proposed to locally strengthen precast prestressed concrete (PPC) driven piles by wrapping them with glass fiber reinforced polymer (GFRP) composites at the end regions. To investigate the feasibility of the proposed solution, five full-scale square PPC piles were manufactured, among which two were strengthened with externally bonded bidirectional GFRP wraps at both ends. All piles were then driven in a sandy soil in a project site using a diesel hammer, while the driving-induced stresses were monitored using a pile driving analyzer system. Direct measurements of the tip strain at each hammer blow were also obtained by using a wireless embedded data collector technique. A static pile load test was also conducted on one of the piles. The field test results showed that the proposed GFRP-wrapping had no negative effect on the skin friction resistance of the PPC piles along their strengthened region. A close inspection of the exhumed piles also revealed that the pile’s tip remained intact during driving with no debonding between the GFRP wrap and the concrete substrate, demonstrating the great potential of the proposed strengthening solution in maintaining the integrity of the PPC piles during driving.