Collapse Mechanisms of Controlled Rocking Steel Braced Frames: Base Rocking Joint vs. Capacity-Protected Frame Members
Bibliographic record
Abstract
Controlled rocking steel braced frames (CRSBFs) have been proposed as a low-damage seismic force resisting system with reliable self-centering capabilities. The frame members in CRSBFs are selected to remain elastic during design-level earthquakes, so they must be designed to resist the peak forces from at least the first-mode pushover response. However, several researchers have shown that higher mode effects can contribute significantly to the peak member forces. Some collapse assessment studies on CRSBFs have included member yielding and buckling in the numerical models, but the studies have not examined a range of possible design intensities for the higher modes, and have not separated the influence on the collapse risk of the capacity design from that of the design of the base rocking joint. This paper presents the collapse assessment results for 12-story CRSBFs that were designed either excluding the higher-mode forces, or including the higher-mode forces at the DBE level, MCE level 1.5 times the MCE level, and 2.0 times the MCE level. The ground motions were selected conditionally based on the first-mode period of each example frame. The probability of collapse during an MCE-level event was computed for the frames when buckling and yielding of the frame members was modeled, and compared to the probabilities of collapse when the members were modeled as elastic. The results indicate that the base rocking joint design was more conservative than required to provide adequate collapse prevention compared to the design of the frame members. Including the higher-mode forces at the MCE level for capacity design seems appropriate from a collapse prevention perspective.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 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) | 0.001 | 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 teacher head, 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".