Modular Hybrid Pier for Naval Ports

Abstract

The Modular Hybrid Pier (MHP) uses post-tensioned, high strength, lightweight concrete with corrosion resistant steel reinforcement to reduce repair costs by up to 80% over a service life of 100 years. The floating, double-decked pier will provide efficient vessel support to reduce costs of ship berthing, repair and re- supply. Costly, maintenance-intensive fender piles are not required as foam-filled fenders positioned along the hull and internal fenders at mooring shafts absorb energy of vessel mooring. This provides optimum flexibility in ship classes that can be berthed. The MHP rides with the tide, maintaining constant elevation relative to ship decks thereby reducing labor expended in tending mooring lines. Introduction. The Naval Facilities Engineering Command (NAVFAC) is leading a consortium in the development, testing and evaluation of concepts and materials technology for a new generation of berthing piers. Lead developing activity is the Naval Facilities Engineering Service Center (NFESC). The NFESC has contracted with Berger/Abam Engineers Inc. under a Broad Agency Announcement contract for concept development and test support. A Test Bed is being constructed at Naval Station, San Diego, CA, for testing of materials, structural and hydrodynamic response. MHP development is guided by an Integrated Product Team (IPT). Members are experienced in facilities acquisition, public works and port operations, and represent technical disciplines that are pertinent to success of MHP development. A Test and Evaluation Master Plan outlines operational requirements, developmental tests and operational tests needed to resolve suitability issues. Concept. The MHP is based on standardized, double-decked floating modules (reference 1). Individual modules measure 27-m width x 99-m length x 9-m height with a 4.3-m draft when fully loaded. Typical pier length is 396-m (4 modules) although two to five modules may be assembled (Figure 1). Pier modules can be added or subtracted to adapt to changing homeport requirements. Modules can be disassembled and reassembled to relocate the MHP for future optimization of regional infrastructure assets. This reduces the risk that the Navy may have to abandon and re-construct valuable pier assets in response to shifts in home port assignments. Access from land is via ramps of nominally 30-m length depending on tidal variations. Current Navy piers are supported by 700 or more piles. MHP floats thereby eliminating the construction and maintenance cost of support and fender piles. Floating, foam-filled fenders positioned along the hull and internal fenders at mooring shafts absorb energy from vessel mooring. This provides optimum flexibility in the types of ship classes that can be berthed.