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Rubber Fender Design – How to calculate berthing energy |
| Author : Date : 10/26/2014 11:37:53 PM |
Rubber Fender Systems for marine structures are generally designed according to the following procedure:
 Berthing energy is calculated by the following kinetic equation Ef= Wa/2g • V2• Cm • Ce • Cc • Cs (4.1 ) Where
Ef: Berthing energy (tf•m) g: Acceleration gravity (9 8m/sec2)
Wa: Water displacement of the berthing ship (tf)
V: Berthing Speed of the Ship at the movement of impact against the fender (m/sec)
Cm: Virtual mass factor
(As a vessel makes contact with the berth and its movement is suddenly stopped by the fenders, the mass of water moving with the vessel adds to the energy possessed by the vessel This is called “Mass Factor” and the weight of the water is generally called “Additional Weight”)
Ce: Eccentricity factor
(In the case when a vessel contacts a berth at a point near its bow or stern, the reaction force with give a rotational movement, which will dissipate a part of the vessel’s energy)
Ce = K2/ (A2+K2) (4.2)
Where
K: Radius of rotation of the vessel (usually 1/4 of vessel’s length) A: Distance of the line paralleled to wharf measured from the vessel’s center of gravity to the point of contact.(usually 1/4- 1/5 of vessel’s length)
Cc: Berth configuration factor
This is the portion of berthing energy which is absorbed by the cushion effect of water between the approaching vessel and the quay wall
Cs: Softness factor
This is the portion of berthing energy which is absorbed by the deformation of the vessel’s hull and fender |
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