UFC 4-152-01
28 July 2005
designed and detailed to resist these forces. In areas of high seismic activity, the
increased stiffness of the system reduces the period and leads to higher
earthquake loads.
4-4.1.3
All Batter Pile System.
This system is a compromise between the two above, and is cost-effective in
some circumstances. With this system, the batter slope may be near vertical.
Natural periods can be as high as several seconds, making the approach
attractive for seismic areas.
4-4.1.4
Batter Pile System with Seismic Isolation.
This system incorporates calibrated isolators or seismic fuses between the wharf
deck and batter piles. The system allows for high displacements of the wharf
deck once a threshold lateral load causes the isolator slip. Consider the
magnitude of lateral berthing and mooring forces such that they do not exceed
the threshold lateral force of the isolator. In this case a separate fendering
structure may be required.
4-5
MOORING HARDWARE.
4-5.1
General.
Ships are usually moored to bollards, bitts, and cleats. Occasionally, ships may
be tied to a quick-release hook. The position of a ship on a berth is usually
controlled by utility hookup and brow location requirements. The crew in charge
of tying up the ship will usually tie the lines to whatever mooring hardware is
convenient to give the required horizontal angle. This often results in lines tied to
a lower capacity cleat while a high-capacity bollard may only be a few feet away.
Hence, consider using only one type of high-capacity mooring hardware
throughout the facility. When possible, size this mooring hardware for the
maximum size vessel that could possibly use the facility. Space hardware to
maximize the berth flexibility for use by ships other than the specific vessel the
berth was designed to accommodate. In addition, mooring hardware
requirements will depend on the mooring service type assigned to the berth as
defined in UFC 4-159-03. For mooring service types III and IV, consider
providing additional heavy weather mooring hardware. Balance the desire to
provide the higher capacity hardware with the additional cost of the higher
strength hardware and supporting structure. The geometry of the hardware
should preclude mooring lines from slipping off, as the mooring angle is often
very steep.
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