Impact Behavior of Prestressed Concrete Piles with Glass FRP Spirals: Experimental and Finite-Element Analysis

Abstract

Corrosion is a major cause of deterioration in conventional steel-reinforced prestressed concrete (PC) piles installed in aggressive (marine) environments. As foundation members in bridges, deteriorated piles may result in failure or expensive repair or reconstruction. Corrosion resistant alternatives for reinforcing piles longitudinally and transversely include carbon fiber composite cables (CFCC) and stainless-steel (SS). However, the cost of these alternatives is prohibitive, which in turn increases the production cost of PC piles. To mitigate the high cost of CFCC and SS piles, the spirals in these corrosion resistant piles can be safely replaced by glass fiber–reinforced polymer (GFRP) bars in spiral form. In this research, the effectiveness of GFRP spirals in confining PC piles is presented by showing results of impact experiments conducted on full-size specimens. One control pile was reinforced with steel strands and spirals, while another pile was reinforced with steel strands and GFRP spirals. The spirals within the piles were instrumented at critical locations with strain gauges to record spiral responses. Externally, pile driving analyzer strain gauges and accelerometers were installed for pile response along loading direction. In addition, to further understand the spatial response of the piles tested, three-dimensional finite-element (FE) models were developed using a commercially available code to simulate the impact test. For the FE model, concrete behavior of was modeled using concrete damaged plasticity model, the behavior of steel strands was simulated using a bilinear elastoplastic material, and the GFRP spiral behavior was modeled using a linear elastic material. The results of the research show that PC piles can be confined with GFRP spirals, without decreasing the load-carrying capacity of the pile. This research brought forth valuable insights with practical implications, particularly regarding the use of glass fiber–reinforced polymer (GFRP) spirals within prestressed concrete applications. The practical applications encompass several key points that stand to influence engineering practices. Notably, both experimental results and finite-element studies assert that prestressed concrete piles reinforced with GFRP spirals exhibit performance comparable to their traditional counterparts employing steel spirals. This similarity extends to a robust response under impact loads, indicating that prestressed concrete piles featuring GFRP spirals as lateral reinforcement can effectively withstand pile driving forces, rendering them suitable for practical applications. Furthermore, the study introduces the prospect of enhancing corrosion resistance in prestressed concrete piles by incorporating GFRP spirals in combination with corrosion-resistant strands. This development expands the feasibility of deploying corrosion resistant prestressed concrete piles for bridge foundations in marine environments. Engineers engaged in bridge construction projects are thus encouraged to explore the adoption of GFRP-reinforced prestressed concrete piles, anticipating enhanced durability and longevity for bridge structures, especially in regions subject to harsh environmental conditions. This plays a pivotal role in advancing resilient and sustainable infrastructure practices within the realm of civil engineering and construction.