Behavior of Post-Tensioning Strand Systems Subjected to Inelastic Cyclic Loading
Bibliographic record
Abstract
Post-tensioning (PT) strands have been employed in a number of self-centering seismic force-resisting systems as part of the restoring force mechanism that eliminates residual building drifts following seismic loading. Unbonded PT strand systems are particularly well-suited for providing elastic restoring force because they possess large elastic strain capacity. Although typically designed to stay elastic during design basis earthquake events, strands may experience inelastic cyclic loading during extreme earthquakes. Furthermore, the yielding and fracture behavior of PT strand systems is central to the collapse behavior of self-centering systems. A testing program was conducted to characterize the cyclic inelastic behavior of monostrand anchorage systems as they might be applied in self-centering seismic force–resisting systems. The experimental program included more than 50 tests with variations in testing protocol (both monotonic and cyclic tests to failure), strand manufacturer, anchorage manufacturer, single-use versus multiple-use anchorage systems, and initial post-tensioning strand stress. Characteristics of the response that were investigated include seating losses, deformation capacity prior to initial wire fracture, additional deformation capacity after initial wire fracture, and aspects of the load-deformation behavior. For the tested monostrand anchorage systems using typical industry barrel and wedge anchorage systems, the mean first wire fracture strain was found to be 2.3% and 2.7% for multiple-use and single-use chucks, respectively, and two standard deviations below the mean (representing a relatively low probability of wire fracture) was 1.2% and 1.3%, respectively. Furthermore, these monostrand anchorage systems were shown capable of an average of 85% additional elongation after first wire fracture. It was concluded that the tested monostrand anchorage systems, because of their high strength, large elastic deformation capacity, ductility prior to wire fracture, and additional postwire fracture deformation capability, are well-suited for self-centering seismic force–resisting systems.
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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) | 0.000 | 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 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".