Experimental Investigation of Bond Fatigue Behavior of Concrete Beams Strengthened with NSM Prestressed CFRP Rods
Bibliographic record
Abstract
Bond tests were conducted on 10 concrete beams strengthened with near-surface mounted (NSM) prestressed carbon fiber reinforced polymer (CFRP) rods under different fatigue load levels. In the NSM technique, grooves are cut on the tension side of the beams. The CFRP rods are then placed inside the grooves and prestressed. Then an epoxy adhesive is placed inside the groove to provide a bond between the concrete and the CFRP rod. The test variables included the type of CFRP rod (spirally wound or sand-coated) and the fatigue load level. The beams were tested in four-point bending. Unlike the bond failures for beams strengthened with nonprestressed CFRP rods, bond failure for beams strengthened with prestressed CFRP rods and tested under fatigue loading was by slipping between the CFRP rod and the epoxy that started at the support and propagated inward toward the loading point. The sand-coated rods showed a better bond fatigue performance than the spirally wound rods, where at a given load level the beams strengthened with sand-coated rods had longer fatigue lives than the beams strengthened with spirally wound rods. Also, for a given number of cycles, the beams strengthened with prestressed CFRP rods failed in bond at a lower applied load range than the beams strengthened with a nonprestressed CFRP rod. At onset of excessive slip (failure), the force distribution in the CFRP rod in the end region was the same for a given rod type. Thus, the shear stress value and distribution in the region close to the support was the same at onset of excessive slip (failure) for a given rod type regardless of the applied load level.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 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".