Reliability of fatigue life predictions for tubular joints with load pattern recognition
- Aker Engineering A.S., Stavanger (Norway)
All parametric formulae for Stress Concentration Factors (SCFs) classify the tubular joints according to the geometry and standard load patterns. Thus the SCFs are purely dependent on geometry, and loadings on the joint braces are ignored which keeps the uncertainty in the SCFs at the same level as the geometric uncertainty. It is shown that the SCFs with load pattern recognition if associated with standard formats for fatigue analysis of offshore platform connection would create theoretical anomalies and practical unsuitability. Particularly, it is shown that these SCFs if associated with deterministic fatigue analysis would violate the basic assumption viz. one-to-one correspondence between the wave height and hotspot stress range. It is shown that multiple values of wave heights may give rise to same stress range. This non compliance of the basic tenet of deterministic fatigue analysis can have significant effect on predicted fatigue life of joints in splash zone. The reliability analysis of fatigue life calculations using SCFs according to load pattern recognition is performed using First Order Second Moment technique. It is shown that fatigue life reliability is less in this case by orders of magnitude compared to one with standard SCFs.
- OSTI ID:
- 433599
- Report Number(s):
- CONF-940409--; ISBN 1-880653-10-9
- Country of Publication:
- United States
- Language:
- English
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