MS Plan B Defense: Feasibility of Fiber-Reinforced Polymer Piles for Marine Fender Systems at Coast Guard Base Kodiak, Alaska

Bethany Stafford
Master’s Student
Department of Ocean and Resources Engineering
University of Hawai’i at Mānoa

**This defense will be held both in person (POST 723) and over Zoom**
Meeting ID: 940 4010 1446
Passcode: BethMS
https://hawaii.zoom.us/j/94040101446

Coast Guard Civil Engineering Unit Juneau contracts a project approximately biennially to replace damaged fender piles at Base Kodiak’s waterfront. Traditionally, this has been a replace-in-kind project that replaces damaged fender piles with the same type of marine-grade Douglas fir as originally installed. This project evaluates the feasibility of using Fiber Reinforced Polymer (FRP) piles, which have a higher material cost, but more favorable material properties than traditional timber. The project site is susceptible to high winds perpendicular to the dock that push the cutters into the pier/wharf and result in pile failure which causes sections of the facility to be condemned by engineers and significantly interrupts the cutter operations. The proposed FRP product is a reinforced plastic matrix pile made out of recycled plastic and reinforced with fiberglass rebar with an ultimate moment capacity approximately 3-times greater than that of timber. Data from the local National Buoy Data Center’s (NDBC) weather station was used to determine a 25-year design wind load. Using a supported cantilever model, timber piles were determined to have insufficient capacity to support the cutters under the design wind load. Four maintenance scenarios were evaluated and compared: (1) continue to replace timber piles with timber piles as they break, (2) replace broken timber piles with FRP as they break, (3) recap the entire system with FRP piles, and (4) recap the system to FRP and reduce the number of piles due to the increased moment capacity of each pile. The findings indicate that if the funding is available, scenario 4, which recaps the system with FRP and reduces the total number of piles is the most financially advantageous for the Coast Guard at this project site. Even though four specific scenarios were evaluated, any level of FRP upgrade that the Coast Guard can afford will prove to have cost savings for the government over time.