API650 seismic loading

[bourguideche]

Hello,

My questions is about the appendix E of the API650 (11 std) :

- The formula 6.2.2.3-1a give us the allowable longitudinal shell-membrane compression stress : Fc=83ts/D. In this formula, what is ts? the thickness of the first course of the shell or the thickness of the plate of the bottom under the shell?
- What is the formula in the appendix E (or in the rest of the code) which allow us to calculate the extra thickness (of each course of the shell) necessary for the extra loading generate by seismic risk?

Thanks in advance for your help.

 

[JStephen]

ts is shell thickness in millimeters, defined in the list of variables at the beginning of Appendix E.

Additional seismic thickness can be due to compressive stress or due to seismic hoop stresses. The section you're looking at is compressive stresses. Seismic hoop stresses are in E.6.1.4.

 

[bourguideche]

Thanks for your answer.

If I understand what you say, the final thickness is the value for :
- (Fc>Sc+St) or (Fc>Sc and FC>St)?

Is it right?