1. The Reconstruction of Kodiak Pier 1 Dock Facility to Modern Seismic Design Standards
- Author
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Daley, John, Scher, Robert, Nielsen, Kim, Anderson, Duane, and Harn, Bob
- Abstract
The Alaska Department of Transportation and Public Facilities, and the Federal Highway Administration, intend to reconstruct the Kodiak Ferry Dock (Pier 1) in Kodiak, Alaska. The existing pier is a multi-propose timber dock built in 1965. It is used by the Alaska Marine Highway System for ferry service, for bulk fuel, and for general cargo operations. The primary goal of the project is to improve the ferry’s mooring and operations by providing a new, larger dock to increase both the berthing face and the deck area. This paper examines the design of a replacement dock facility and the application of modern seismic design standards. The history of Kodiak is intertwined with seismic events and tsunamis. The first Russian colonists recorded several large earthquakes and the original settlement at Old Harbor was wiped out by a tsunami in 1788. The most notable seismic event in modern recorded history was the Great Alaska Earthquake in 1964, in which Kodiak experienced significant loss—resulting, primarily from the 20 to 30 foot tsunami waves that wiped out low lying areas, including the Pier 1 waterfront area. Significant tectonic vertical displacements occurred in the vicinity, with about 5.8-ft of subsidence at the Pier 1 site. Most pile supported piers and wharves in Alaska today were designed with simple code-complaint life safety protection for seismic and might include steel pipe piling (plumb and batters), steel pile caps, and a precast concrete deck, all cost effective elements for remote areas. The design of the majority of these docks can be characterized as “forced based”. Recent testing has shown that steel pile to steel pile cap welded connections and batter piling are not inherently ductile. Couple non-ductile details with force based design and it is likely that the designer cannot fully predict or describe the performance of the entire structure in a major seismic event. 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 ASSHTO LRFD Bridge Design Specifications. Implementation of these standards is discussed, as well as the real-life limitations and risks that remain even after the new design. The new dock includes vertical steel pipe piling with a composite reinforced concrete interior that is socketed into shallow bedrock as a drilled pier foundation. A reinforced concrete pile cap was provided and the decking consists of precast pre-stressed concrete panels. The paper outlines a “displacement based” design philosophy centered on achieving a controlled ductile response to seismic forces. A central structural design goal is to provide a ductile moment frame consisting of vertical piling, pile caps, and precast concrete deck beams and panels. The pile-to-cap connection is designed to yield in a controlled ductile manner while other elements including the pile cap and deck are to remain elastic under seismic forces. A pushover analysis was used to confirm these goals were achieved.
- Published
- 2014
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