Fatigue Stress Evaluation at Shell-to-Bottom Joint With Double Plastic Hinge in Elevated Temperature Steel Tanks on Concrete Ring Walls
Bibliographic record
Abstract
The shell-to-bottom joint of hydrocarbon storage tanks is a critical location which may experience fatigue cracking and requires evaluation of the local cyclic stresses especially in the case of elevated temperature tanks. The fill/draw down cycle of the stored liquid causes low cycle fatigue near this joint and hence a fatigue evaluation is recommended. The peak alternating stress at this location, used to enter the fatigue curves is currently determined using a pseudo-elastic analysis that represents strain range due to inelastic deformations. API 650 employs beam on elastic foundation theory for this analysis. This theory is being used for tanks resting fully on earthen foundation as well as those on concrete ring wall. This paper studies the validity of using this theory for tanks with concrete ring wall foundation which are much more rigid compared to earthen foundations. Some of the difficulties in the current practice are highlighted. An alternative to the current model is presented for the determination of stresses in such tanks. The results are validated using finite element analysis. The results show that the current practice needs to be revised or rejustified in an alternative manner.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".