Department: Structural Engineering
P. Benson Shing | Chia-Ming Uang | Scott Ashford
Name: Jerry Lee
Email: jjl011 @ ucsd.edu
Grad Year: 2008
The Modular Hybrid Pier (MHP) was developed in conjunction with Berger/ABAM engineers and over 25 government agencies, private firms, and universities to provide the U.S. Navy with a new pier structure to support its combatant ships. This innovative design consists of floating modular sections constructed from prestressed concrete wall panels and beams, as well as post-tensioned concrete slabs. Each module has two levels for operations and utilities and a lower level to provide floatation. Because each section is floating, the MHP utilizes piles for mooring, but not as support vertical loads. This design creates a seismically isolated structure that is less dependant on local tide and soil conditions. The MHP can be constructed off-site and towed to its required location, or relocated as needs change, which allows the U.S. Navy to take full advantage of its expected 100-year repair-free service life. A prototype MHP test structure was constructed in Washington and towed 1,100 nautical miles to the 32nd street U.S. Naval Base in San Diego, and is kept in position by two mooring shafts. The test structure has a length of 100 ft., a width of 50 ft., and a height of 29 ft. A steel fabricated truss bridge links the MHP to land and raises or lowers with the tides. The role of UCSD's structural engineering team is to assess the structural capacity of the deck, bollard, and fender system through four tests. The post-tensioned operations deck will be tested with a hydraulic jack to simulate the load from an outrigger crane at a critical point in the deck. The bollard, which is used to moor ships, will be tested with hydraulic jacks to verify its capacity to keep ships docked and to set a standard for bollard capacity tests. The other two tests involve the pile-to-MHP connection, which is damped through rubber fenders. A long-term test will verify the performance of the fenders when subjected to a static horizontal load in addition to normal wind and tidal loads for 45 days. A short-term test will be conducted using two hydraulic actuators to load the fenders biaxially to examine pre- and post-buckling behavior.
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