Canadian seismic design provisions for single-storey buildings with flexible metal roof deck diaphragms
Bibliographic record
Abstract
The seismic design provisions of the 2015 National Building Code of Canada (NBCC) for single-storey steel buildings with flexible metal roof deck diaphragms are presented. The 2015 NBCC provisions include a new expression for the fundamental period of vibration of buildings used to determine the minimum seismic design loads. The new period equation accounts for the flexibility of both the vertical bracing and roof diaphragm components. The NBCC also requires that the inelastic deformation demand on the vertical bracing elements be evaluated with consideration of the diaphragm in-plane flexibility effects. If needed, the design must be corrected to keep the anticipated deformations within the system deformation capacities. Magnification of roof diaphragm in-plane shears and moments due to diaphragm flexibility must also be taken into account for the design of the diaphragm. The new provisions are applied to a prototype single-storey building. Concentrically braced frames (CBFs) of the moderately ductile category are used and two bracing systems are examined: tension/compression and tension/only bracing. In addition, the building is assumed to be located at two different sites in eastern and western regions of Canada to account for the differences in seismic hazard. The buildings are assumed to be constructed on firm ground sites. In design, diaphragm shears and moments were predicted using a modified response spectrum analysis method. The design is found to significantly influenced by the seismicity level at the site and the bracing system used, which resulted in various properties and overstrength levels among the structures studied. The seismic response of the structures was examined though nonlinear response history analysis. The analyses showed that diaphragm flexibility effects on braced frame deformations were not pronounced for the structures studied. Diaphragm shears and moments can be well predicted using the proposed method. © 2024, International Association for Earthquake Engineering. All rights reserved.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.009 | 0.001 |
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".