Critical review of the CSA A14-07 design provisions for torsion in prestressed concrete poles
Bibliographic record
Abstract
This paper focuses on the effect of the transverse reinforcement in concrete poles and its influence on torsional strength in an effort to simplify the governing Canadian prestressed concrete pole code (CSA A14-07). The rationale behind the CSA code values for amount, spacing, and direction of the transverse reinforcement is not apparent. A testing program consisting of 14 concrete pole specimens were produced to investigate the torsional response. The specimens were divided into two groups with different tip diameters. Within each group the spacing and direction of the wound helical transverse reinforcement varied. Experimental cracking torque values were compared with calculated theoretical cracking torques from ACI 318, Eurocode 2, and various journal articles. The theoretical predictions were generally unconservative. Post-cracking behaviour was modelled using the Compression Field Theory (CFT) and Softened Truss Model (STM) for torsion. It was found that the CFT predicts the post-cracking response with reasonable accuracy. The failure mode in pure torsion is brittle and sudden, and the transverse reinforcement provides no post-cracking ductility. The primary function of the transverse reinforcement is to minimize the longitudinal precracking due to prestressing transfer forces. CSA A14 transverse reinforcement spacing requirements were compared against code minimum spacing requirements and a strut and tie model of the prestressing force transfer zone. Based on the strut and tie model of the transfer zone it was concluded that the CSA A14 helical reinforcement spacing values were insufficient to resist the transfer forces. New helical reinforcement spacing values were recommended to simplify the current CSA A14 code requirements. In addition concrete mix designs, prestressing levels, and wall thicknesses all have a large impact on torsional capacity and therefore quality assurance of these factors should be emphasized in CSA A14.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.005 | 0.011 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.004 | 0.002 |
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".