Safety of gravity-load columns in shear wall buildings designed to Canadian standard CSA A23.3
Bibliographic record
Abstract
It has been a Canadian code requirement for 25 years to check whether concrete gravity-load columns can tolerate the building deformations due to the design earthquake; but the way this has typically been done using linear analysis significantly underestimates the seismic demands on gravity-load columns. Concern about the safety of gravity-load columns over the plastic hinge height of concrete shear walls, particularly elongated wall-like gravity-load columns, has resulted in new design requirements in Update No. 3 of Canadian Standard Association (CSA) A23.3–04 issued in August 2009. The current paper provides the background to these new requirements. If nonlinear analysis is not done, closely spaced seismic hoops shall be provided in all columns and walls that support gravity loads, and these members shall meet the same limit on maximum compression strain depth as concrete shear walls. The results of nonlinear analyses were used to validate this simple design rule, and to investigate factors that increase seismic demands on gravity-load columns such as diagonal cracking of concrete shear walls, localized damage of columns from cover spalling and bar buckling, and larger first storey heights. Nonlinear analysis has shown that 2.4 m (8 ft) long columns can lose over 50% of their axial load carrying capacity at an inelastic drift ratio of only 1%.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".