The Reconstruction of Kodiak Pier 1 Dock Facility to Modern Seismic Design Standards

Abstract

The Alaska Department of Transportation and Public Facilities, and the Federal Highway Administration, intend to reconstruct the existing Pier 1 ferry dock in Kodiak, Alaska. This site has a long history of significant seismic events, the most recent in 1964 which wiped out the waterfront area due to tsunami waves and nearly 6-ft of vertical subsidence. This paper examines the design of a replacement dock facility and the application of modern seismic design standards. Most pile supported piers and wharves in Alaska today were designed using a “force-based” design approach and typically include vertical and battered steel pipe piling, steel pile caps, and a precast concrete deck. Recent testing has shown that welded steel pile-to-cap connections and batter piling are not inherently ductile, resulting in a design where the performance of the entire structure in a major seismic event cannot be accurately predicted. To improve on this, the design team adopted the ASCE Draft Seismic Design of Pile Supported Piers and Wharves as a governing document along with AASHTO bridge design specifications. Implementation of these standards utilized a “displacement-based” design philosophy centered on achieving a controlled ductile response to seismic forces of a moment frame consisting of vertical steel piling, concrete pile caps, and precast concrete deck members. A pushover analysis was used to confirm these goals were achieved.