Page 469 - Marine Structural Design

Chapter 25 Reliability of Ship Shuctures 445

CY, =do2 +ut, +k:oid +kik:otd +2pMwMdkwkdoM,~Md (25.6)
M.
where
Mu = ultimate strength
M, = still water bending moment
M, = wave bending moment

Md = dynamic bending moment
k, = load combination factor for still water and wave/dynamic moments
kd = load combination factor for wave and dynamic moments

pi = mean of component i
IS^ = standard deviation of component I
b. For Secondary and Tertiary Failure Mode
g = fuSM - [M, + k, (Mw + kdMd)] (25.7)

(25.8)

= section modulus
= ultimate stress
= still water bending moment
= wave bending moment
= dynamic bending moment
= load combination factor for still water and wave/dynamic moments
= load combination factor for wave and dynamic moments
= mean of component i
= standard deviation of component i

25.3 Load Effects and Load Combination

The following sections are based on Sun and Bai (2001) with some modifications. FPSOs hull
girders are predominantly subjected to combining actions of stillwater and wave-induced
bending moments. Still water bending moment (SWBM) is created from the action of the ship
self-weight, the cargo or deadweight and the buoyancy. Differently from ocean-going cargo
ships, the SWBM of an FPSO varies more frequently from one load condition to another due