Higher capacity cold-formed steel sheathed and framed shear walls for mid-rise buildings: Part 2
Bibliographic record
Abstract
Despite the increase in the use of cold-formed steel (CFS) in mid-rise construction (up to 5 storeys), the North American cold-formed steel standards AISI S400 and S240 do not provide a standard design procedure for CFS sheathed and framed shear walls for use in such constructions. The main objective of this research was to develop a design procedure for CFS sheathed and framed shear walls to achieve higher strength and ductility and resist the larger forces expected in mid-rise construction. The design procedure proposed for inclusion in the AISI S400 and S240 standards.Full-scale experiments have been performed using a shear wall testing frame at McGill University where a total of 31 specimens were tested monotonically and / or cyclically. These specimens were constructed with thicker sheathing and framing members not currently available for design, using two innovative building configurations (double-sheathed and centre-sheathed) to eliminate the effects of eccentric sheathing placement and take full advantage of bearing failure in the sheathing.The specimens were built with varying construction parameters (material thickness, screw size and screw spacing) and the test data was analysed using the Equivalent Energy Elastic-Plastic (EEEP) method. The configuration using a single concentric sheathing placement (centre-sheathed configuration) reached shear strengths nearly four times higher than what is listed in the current standards. Further, the walls’ ductility was substantially improved (up to 8% drift), giving this design a strong potential to be used in mid-rise construction. A preliminary design method was introduced for this configuration, taking into consideration the different behaviour from these shear walls. A preliminary Limit States Design procedure for Canada (LSD) and the USA and Mexico (LRFD) was determined based on the test results. Resistance factors and overstrength values were also provided. The “test-based” ductility-related and overstrength-related seismic force modification factors for Canada (Rd and Ro) obtained the values of 2.8 and 1.5. This promising centre-sheathed configuration requires further research in order to advance towards a definitive design method for the use of CFS framed and sheathed shear walls in mid-rise construction.
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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 | 0.001 |
| 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 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".