Seismic induced floor accelerations and diaphragm forces for buckling restrained braced frames
Bibliographic record
Abstract
Floor and roof diaphragms are essential part of seismic force resisting systems in building structures. They must be designed to withstand and transfer forces that are induced by floor acceleration in an event of strong earthquakes. Reconnaissance reports of major earthquakes have shown that diaphragms structural integrity is one of the key factors to obtain satisfactory seismic performance of structural systems. This article presents a comparison between Canadian and U.S. building code provisions regarding diaphragm seismic design forces and a case of 10-storey buckling-restrained braced frame is elaborated as an example. Despite the general similarities, building codes in the two countries prescribed significantly different design values for the case studied. The results of nonlinear time history analysis conducted on 3 to 15-storey code-conforming ductile steel braced frames are then compared to the Canadian code (NBCC) specified design values. These analyses show that diaphragm forces exceed the design values by a significant margin and diaphragms overload can be repeated many times during a typical design level earthquake. Current peak floor accelerations defined in NBCC for the design of non-structural elements and building components is also shown to be overlay conservative, especially at the roof level. Large diaphragm forces are generated as a result of time delays between storey shear forces in adjacent storeys with maximum values occurring during elastic phases of the response. This delay is strongly related to the ground motion intensity and frequency content. Based on the observations made in this study, possible avenues are proposed to improve design provisions for peak floor accelerations and diaphragm inertia forces. © 2017, 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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".