Viscoelastically Enhanced Buckling Restrained Braces for P-Delta Cancellation and Reduced Residual Drifts
Bibliographic record
Abstract
An innovative viscoelastic buckling-restrained brace (VE-BRB) is proposed as an enhancement to conventional buckling-restrained braces (BRBs). This brace mitigates P-delta effects, introduces a recentering capability, and provides enhanced inherent damping, thus enhancing the seismic performance of tall steel buildings in high-seismic regions, especially under subduction interface seismic events. The VE-BRB enhances a conventional BRB with viscoelastic dampers mounted directly on the BRB restrainer, functioning in parallel with the BRB core element. The viscoelastic dampers are designed with sufficient elastic stiffness to counteract P-delta effects and induce recentering without the need to amplify story design forces using the code-prescribed stability coefficients. The proposed brace is described in detail, including design equations tailored for multistory steel buildings. To evaluate its effectiveness, the braces were implemented as seismic-force resisting systems in 10- and 20-story prototype buildings located in Vancouver, BC. These buildings were compared with conventional BRB frames designed with amplified design story shear forces using the inelastic stability coefficient, as prescribed in the Canadian Building Code. Nonlinear response history analyses were conducted using seismic records from crustal, in-slab, and subduction interface sources. The VE-BRB system demonstrated superior performance compared with conventional counterparts, achieving more-uniform drift distributions along the building heights and controlling residual drifts within repairable limits. Detailed finite-element (FE) models were developed to validate the proposed design assumptions at the brace component level, including restrainers, connections, bolts, and gusset plates. Conventional BRB models were calibrated against past cyclic test data, followed by models incorporating the viscoelastic dampers. Full-scale FE models of the 6th and 10th stories of the 10- and 20-story VE-BRB frames were subjected to quasi-static cyclic pushover analyses, because these floors correspond to available matching calibration experimental test data. The results confirmed the adequacy of the proposed design assumptions and demonstrate robust and stable performance of the VE-BRB system under extreme drift demands.
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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 | 0.000 |
| 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 | 0.001 |
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".