Impact of New ACI 318 Flexural Resistance Factor on Bond Failures
Bibliographic record
Abstract
Monte Carlo simulation is used to quantify the reliability of reinforced concrete cantilever beams without stirrups designed using ASCE 7-98 load factors with strength reduction factors given in Appendix C of ACI 318-99 and the main body of ACI 318-02. Limit states corresponding to flexural failure neglecting strain hardening of the reinforcement, flexural failure considering strain hardening, and bond failure are investigated for various dead-to-live load ratios, reinforcing bar sizes, and flexural reinforcement ratios. Development lengths for the simulated beams were computed using ACI 318-02 Eq. (12-1). Computed mean-value, first-order, second-moment reliability indices confirm the simulation results, but in all cases slightly overestimate the reliability. Bond failures are more probable than flexural failures, and more probable for beams with small diameter bars than for beams with large diameter bars. Flexure and bond reliabilities are lower for the beams designed to ACI 318-02 than for the beams designed to ACI 318-99 for reinforcement ratios less than 0.023. Flexural reliability indices are more consistent for the beams designed to ACI 318-02, but bond reliability indices are more variable. To improve the consistency and magnitude of bond reliability indices for beams designed to ACI 318-02 the reinforcement bar size factor γ could be increased from 0.8 to 0.85 and development lengths could be increased by 22 to 27% for small diameter bars and up to 19% for large diameter bars. The bar size factor may have to be increased further to accommodate bars with confining reinforcement and also reinforcement detailed using the simplified equations in Section 12.2.2 of ACI 318-02.
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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 | 0.002 | 0.005 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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".