UFC 4-152-01
28 July 2005
c. AQWA. The Naval Facilities Engineering Service Center (NFESC-
ECDT) typically uses the COTS AQWA software package to perform a
dynamic analysis of berthing through six degrees of freedom in the time
domain.
d. Analytical Model. NFESC has developed an analytical model that can
accurately predict ship berthing impact forces. The model employs a
computational fluid mechanics approach, coupling a Reynolds-Averaged
Navier-Stokes (RANS) numerical method with a six-degree-of-freedom
motion program for time-domain simulation of ship and fender reactions.
The model has been verified with data from small-scale and full-scale
tests. Results from the new model for two ship classes yield added mass
coefficients close to those calculated by the PIANC formula as long as the
depth-to-draft ratio exceeds 1.2. When the underhull clearance becomes
small, i.e. for depth-to-draft ratios less than 1.2, predicted added mass
coefficients can exceed the PIANC values. Added mass values of 5.0 or
higher are predicted for ships berthing against open piers (pile supported)
equipped with soft fenders, such as pneumatic or foam-filled cushions.
Consider using higher values for the added mass coefficient under these
conditions.
e. BeAN. The two previous rigorous analytical models can produce
results of superior accuracy, however, they are not always required or
always suitable for all cases of analysis. A software program for berthing
analysis, BeAN (ref Software Development for Berthing Analysis and
Structural Loading on Waterfront Facilities), has been developed. BeAN is
a simplified, desktop mathematical model that calculates time histories of
fender forces, deflections, and vessel motions. The model examines open
or closed type berthing facilities, various depths, eccentric or centric
vessel impact, and nonlinear fender structures.
5-3
TYPES OF FENDER SYSTEMS.
5-3.1
General.
Fender systems absorb or dissipate the kinetic energy of the berthing ship by
converting it into potential energy in the fender materials. This could be in the
form of deflection of a fender pile, compression of a column of rubber,
deformation of a foam-filled cylinder, torsion of a steel shaft, or pressuring of a
pneumatic fender.
5-3.2
Fender Piles.
This is the most commonly used system in existing Navy piers and wharves.
This system is stiff and lacks the capacity for large deflection which results in
high reaction loads and frequent breakage of piling and hull damage. This
system employs a series of closely spaced fender piles (5- to 10-ft spacing)
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