Damage Threshold of Near-Cross-Ply and Angle-Ply Tubes Used in Concrete Filled FRP Tubes Loaded in Flexure
Bibliographic record
Abstract
Concrete-filled fibre-reinforced polymer (FRP) tubes (CFFTs) have been studied extensively, but a lingering question remains regarding the vulnerability of the exposed tube to accidental damage or vandalism. In this thesis, the effect of damage induced in the tubes on the flexural strength of CFFTs is studied. Two commonly available types of tubes are explored, one with near-cross-ply having nearly orthogonal fibre arrangements, and one with large (±55°) angle-ply fibre arrangements. Eighteen CFFTs using the former tube and twelve CFFTs using the latter tube were tested in four-point bending, including undamaged control specimens to establish their full nominal strength (Mno). Full wall thickness cuts were introduced in the glass-FRP tubes in the circumferential and longitudinal directions, on both the tension and compression sides. The cuts also varied in length, as a ratio of the outer perimeter πD, and their proximity to neutral axis was varied for one type of tubes. It is shown that the most critical cut for both tubes is the circumferential one on extreme tension side. The reduced-to-control ultimate moment ratio (Mn/Mno) of the angle-ply CFFTs reduces almost linearly from 1.0 to 0.36 as the cut length increases from zero to 20% (πD). This is much less critical than in near-cross-ply CFFTs, where (Mn/Mno) drops sharply from 1.0 to 0.55 at a 2% (πD) cut, then gradually to 0.25 at a 20% (πD) cut. The maximum difference between angle-ply and near-cross-ply CFFTs seems to occur around the 10% (πD) cut, where (Mn/Mno) ratio of the near-cross-ply CFFT is only half that of angle-ply CFFT. As the location of a 3% (πD) circumferential cut shifted from extreme tension to an 80° angular location from the bottom of a near-cross-ply CFFT, (Mn/Mno) increased from 0.52 to 1.0. Longitudinal tension cuts caused (Mn/Mno) to drop linearly from 1.0 to 0.47 at a 22% (πD) cut length, which was similar for both tubes. Compression side longitudinal and circumferential cuts were less critical with (Mn/Mno) being 0.8 to 0.9. For practical design purposes, a case study based on ultimate static strength showed that CFFTs similar to the ones tested in this study can tolerate a circumferential tension cut up to 30% (πD), for both tube types, before they have to be taken out of service or repaired.
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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 | 0.001 |
| 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 | 0.001 | 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".