GFRP Bars in Structural Design: Determining the Compressive Strength versus Unbraced Length Interaction Curve
Bibliographic record
Abstract
To mitigate the durability issues arising from steel reinforced structures, current research in the structural engineering field has been focused on the feasibility of replacing steel with corrosion resistant materials. A promising alternative has been glass fibre reinforced polymer (GFRP) bars as internal reinforcement. While extensive testing has certified that GFRP bars perform adequately as tensile reinforcement, structural design codes have yet to adopt provisions for its implementation as compressive reinforcement. Quantifying the compressive behaviour of GFRP bars – the relationship between strength and unbraced length, as well as the modulus of elasticity – is the first step toward developing code provisions. This experimental program consisted of 34 specimens of 25M GFRP bars tested under direct compression; the lengths of the specimens were varied to establish the relationship between length and strength. A pure crushing failure with an ultimate compressive strength of 730 MPa was observed for all specimens under the nominal unbraced length of 230mm. Longer specimens failed through a global buckling of the bar, with ultimate compressive strength decreasing with increasing unbraced bar length. The average compressive modulus of elasticity was determined to be 60 GPa. Les structures renforcées par l’acier risquent souvent de manquer de durabilité. Pour minimiser ce risque, des études actuelles dans le domaine de l’ingénierie des structures se focalisent sur la possibilité de remplacer cet acier avec des matériaux qui sont plus résistants à la corrosion. Une nouvelle option possible pour renforcer les structures est le polymère renforcé de fibre de verre (PRF). Malgré le fait que les barres en PRF performent systématiquement de façon adéquate comme renforcement extensible, elles n’ont pas encore été adoptées par les codes de construction comme renforcement contre la compression. Pour pouvoir utiliser les barres en PRF selon le code, il faudra quantifier leur comportement lorsqu’elles sont soumises à la compression, soit la module d’élasticité et la relation entre leur force et leur longueur. Ce programme expérimental comporte 34 exemplaires de barres PRF de 25M, sans support externe, qui ont été testés sous compression direct. La longueur des exemplaires varie pour mieux établir la relation entre longueur et force. Un échec total à cause de la compression après 730 MPa a été observé pour tous les barres en dessous de 230 mm. Les barres qui étaient plus longues que 230 mm se sont déformées sous compression; globalement, la résistance à la compression a diminuée lors de l’augmentation de la longueur de la barre. La moyenne de compression élastique a été déterminée à 60 GPa, selon les dimensions données par l’équipement utilisé au début de chaque essai. Cette valeur est identique à la moyenne publiée pour les barres sous tension.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".