Seismic Collapse Risk Assessment of Posttensioned Controlled Rocking Masonry Walls
Bibliographic record
Abstract
The use of vertical unbonded posttensioned (PT) bars in masonry walls results in a controlled rocking behavior that can provide a high drift capacity and recenter the wall to its vertical alignment, minimizing residual drifts after a seismic event. However, because posttensioned controlled rocking masonry walls (PT-CRMWs) are a relatively new seismic force resisting system relative to conventional reinforced masonry (RM) walls with bonded reinforcement (i.e., fixed base walls), no distinct seismic response modification factors are yet provided in North American building codes and design standards for PT-CRMWs. In addition, following the FEMA P695 methodology, the National Institute of Standards and Technology (NIST) reported that some conventional low-rise RM walls could experience an excessive risk of collapse under the maximum considered earthquake (MCE). For these reasons, the current study evaluates the collapse risk of PT-CRMWs when designed using the seismic response modification factors currently assigned for special RM walls. In this respect, OpenSees is first used to develop and validate multispring macro models to simulate the seismic response of 20 PT-CRMWs with different configurations and axial load levels. The models are then used to perform nonlinear static and dynamic analyses following the FEMA P695 methodology, which involves evaluating the wall overstrength and seismic collapse margin ratio relative to the MCE. The results demonstrate that low-rise PT-CRMWs, designed with the seismic response modification factors currently assigned by the North American building codes and design standards to special RM walls, can meet the FEMA P695 acceptance criteria for the expected seismic collapse risk under the MCE. However, the peak forces in high rise PT-CRMWs are governed by higher mode effects, which increase the collapse risk due to shear. Finally, the influence of confinement on reducing the collapse risk of PT-CRMW archetypes is evaluated.
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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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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 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".