Experimental Behavior of Low-Ductility Brace Connection Limit States
Bibliographic record
Abstract
In low-ductility, concentrically braced steel frames (CBFs) with traditional fillet welds between the gusset plates and slotted HSS braces, fracture of the fillet welds or net section rupture of the tube are viewed as the most likely connection failure modes. After such failure, the braces lose all their tensile strength but may still re-engage in compression to provide some degree of reserve strength to the structure. A test program was recently completed to verify the behavioral limit states and probable re-engagement strength of brace connections. Six specimens with slotted-HSS welded-gusset plate connections were examined in this research. The connection specimens were part of a 9-story prototype building with chevron CBFs located in eastern North America and designed with an R factor of 3.0. The connection specimens were proportioned to exhibit weld or net section rupture failure modes. The tests showed that connections can re-engage in compression after weld or net section rupture when the edge of the HSS slot comes into contact with the edge of the gusset plate. For slender gusset plates, connection buckling occurred due to the eccentricity resulting from unsymmetrical damage modes - such as coupled weld and net section ruptures - before substantial connection re-engagement can develop in bearing.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 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".