Testing of conventional construction W-shape brace members and their bolted end connections undergoing reversed cyclic loading
Bibliographic record
Abstract
In Canada, the seismic design of steel structures involves the principle of capacity based design, which takes advantage of the inelastic ductility of the Seismic Force Resisting System (SFRS).Specific to concentrically braced frames, the moderate ductility (MD) and limited ductility (LD) categories both require that the members and connections in the lateral load carrying path be designed for the probable capacity of the braces in tension and compression.However, there also exists the Conventional Construction (CC) category as outlined in Clause 27.11 of the CSA S16-14 Standard, for which the engineer is allowed to waive capacity based design principles and design a SFRS which is expected to behave principally elastically when subjected to design-level earthquakes.These Type CC systems are designed using low R-values (Ro = 1.3 & Rd = 1.5), and hence do not depend on the yielding and buckling of a fuse element (brace) to dissipate earthquake energy.Instead, the energy dissipation is assumed to occur due to localized yielding of connections and through friction within these joints.The CSA S16-14 Standard requires the engineer to increase the seismic forces by a factor of 1.5, if it cannot be demonstrated that the connections in the lateral load carrying path have an expected failure mode that is ductile.This has proven to be challenging to engineers because no guidelines or recommendations are provided to determine the ductility of connections.As a result, quantifying the level of ductility of these components becomes an important factor in designing Type CC systems under seismic loading.While Type CC braced frames are used extensively throughout the country, there is very little research available to give insight on the ductility of these systems, particularly in the case of Wshaped braces with bolted end connections.As such, the objective of this research was to measure the response of full-scale W-shape braces and their bolted connections under reversed cyclic seismic loading.Six brace specimens were tested, including two common bolted connection types and two W-shape section sizes.These connections were designed following the provisions in CSA S16-14 without any capacity design rules.The 1.5 penalty from Clause 27.11 was not included.The loading protocol was developed using statistical data from a nonlinear v ACKNOWLEDGEMENTS First and foremost, I would like to express my deepest gratitude to my two supervisors,
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".