Analysis of concrete beams prestressed and post-tensioned with externally unbonded carbon fiber reinforced polymer tendons
Bibliographic record
Abstract
Fiber reinforced polymer (FRP) tendons are being increasingly used nowadays in prestressing and (or) post-tensioning concrete structures. However, designers are faced with lack of practical analysis procedure that leads to proper evaluation of their structural performance, especially when bonded prestressing is combined with unbonded post-tensioning. This paper presents an analytical procedure for these beams. It examines the load–defelction characteristics and proceeds to estimate the ultimate load carrying capacity by taking into consideration the change of stress that occurs in the externally unbonded tendons during different stages of loading. The analytical procedure uses the concept of effective moment of inertia of concrete beams. The equations used are developed by ACI Committee 440, the Intelligent Sensing for Innovative Structures (ISIS) Canada Research Network, and the Comité Euro-International du Béton - Fédération International de la Précontrainte (CEB-FIP), for calculating the deflection of beams reinforced with carbon fiber reinforced polymer (CFRP) tendons. Finite element analyses have been conducted to verify the proposed analytical method. Two experimental programs were used to validate the proposed analytical method. The experimental findings of two box beams reinforced with bonded and unbonded external tendons are compared with finite element analyses and the analytical results. A full-scale test for an internally and externally prestressed double-T beam was undertaken at Construction Technology Laboratories Inc., Skokie, Illinois. The results from this experimental work were used to validate the analytical procedure.Key words: bonded CFRP tendons, concrete, post-tensioning, unbonded CFRP tendons.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.000 | 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 teacher head, 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".