Dear All,

I am involved in FPSO Stress Anlysis project, and just found some different consideration from what usually i found.

Can we combined SUS case with EXP case as you see in case below:

L1 W (HGR)
L2 W+T3+P1
L3 WW+HP(HYD)
L4 W+P+H (SUS)
L5 T1 (EXP)
L6 T2 (EXP)
L7 U1 (SUS) Sway Acceleration
L8 U2 (SUS) Heave Acceleration
L9 U3 (SUS) Surge Acceleration
L10 D1 (EXP) Deck deflection due to sag or hog load/offload
L11 D2 (EXP) Deck deflection due sag or hog waves
L12 D3 (EXP) x,y,z module distortion as deck strains during
load/offload operation
L13 D4 (EXP) x,y,z module distortion as deck strains due to
wave deck strain
L14 D5 (EXP) x,y,z module distortion as deck strains due to
wave acceleration
etc......
.......
.....
....
L18 +L7+L8+L9 (SUS) Combine acceleration loading
L19 +L7-L8+L9 (SUS) Combine acceleration loading
L20 -L7+L8+L9 (SUS) Combine acceleration loading
L21 -L7-L8+L9 (SUS) Combine acceleration loading
L22 +L7+L8-L9 (SUS) Combine acceleration loading
L23 +L7-L8-L9 (SUS) COmbine acceleration loading
L24 -L7+L8-L9 (SUS) Combine acceleration loading
L25 -L7-L8-L9 (SUS) Combine acceleration loading
L26 +L7+L8+L9 (SUS) Worst summary of accl'r load comination
Amplitude values only
L27 2L7+2L8+2L9 (SUS) Worst summ accl'r load, Range values
Limit values is DNV Compliance limit
for high frequency cyclic stress limit
L28 L10+L12 (EXP) Low cycle displ. reaction (amplitude value)
L29 +L11+L13+L4 High cycle displ.reaction (amplitude value)
L30 2L10+2L12 (EXP) Low cycle displ.reaction (Range value)
L31 +2L1+2L13+2L14 (EXP) High cycle displ.reactn (range value)
etc...
...
...
L46 L5-L6+L27+L30+L31 (EXP) Cyclic loading evaluation for low
frequency/high displ.stress
(DNV compliance limit)

My question is:

See combination case in Case 46, the other case is EXP case only Case 26 is sustained.
Can we combine SUS case with EXP case like in Case 46 above?
betwwen primary and secondary stress? that have different characteristic?
Please share your opinion, as i never found case like this.
Thank You.

Does anybody have experience in Combining SUS Case with EXP case for Cyclic stress in FPSO with DNV code as references?

Moverz? maybe you know, does in Bob Robleto session explain about this? i do't remember.....

ICan somebody comment here....as for i now Code philosophy asking for seperating sustained case with self limiting secondary stress, but i don't know whether DNV code apply yhis philoshopies...any comment or valuable input, please..

The DnV code (1996) for Offshore Piping does not consider this separation of failure mechanisms. Refer to the equations in the CAESAR II Quick Reference Guide for details.