Design of Controlled Rocking Steel Frames to Limit Higher Mode Effects
Bibliographic record
Abstract
Because conventional seismic force resisting systems rely on yielding of key structural members to limit seismic forces, structural damage is expected after a design-level earthquake. Repairing this damage can be very expensive, if it is possible at all. Researchers have been developing a new family of self-centring systems that avoid structural damage. One such system is a controlled rocking steel frame, which is the subject of this thesis. \nIn a controlled rocking steel frame, the columns of a frame are permitted to uplift from the foundation, and the response is controlled by using a combination of post-tensioning and energy dissipation. Although previous studies have confirmed the viability of this system, they have also shown that rocking does not fully limit the peak seismic forces because of higher mode effects. If a structure is designed to account for these effects, it may be uneconomical, but if it is not designed to account for them, it may be unsafe.\nThe purpose of this thesis is to develop recommendations for the design of controlled rocking steel frames, particularly with regard to higher mode effects. A theoretical framework for understanding higher mode effects is developed, and large-scale shake table testing is used to study the behaviour of a controlled rocking steel frame. Two mechanisms are proposed to mitigate the increase in structural forces due to higher mode effects, and these mechanisms are validated by shake table testing. Numerical modelling of controlled rocking steel frames is shown to become more reliable when higher mode mitigation mechanisms are used to limit the seismic response. In the final chapters, the thesis proposes and validates a new methodology for the limit states design of controlled rocking steel frames.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".