The University Bridge Arch Assessment - A New Approach
Bibliographic record
Abstract
The University Bridge in Saskatoon is a multi-span concrete arch bridge with a service life that began in 1916. Rehabilitation of the bridge deck is currently underway and expected to be completed during the summer of 2015 with rehabilitation of the bridge arches and piers planned to occur in 10 to 15 years. This manuscript outlines an investigation taken to evaluate a number of different arch rehabilitation strategies using numerical models and experimental data. The rehabilitation strategies considered in this investigation include: do nothing, Fiber Reinforced Polymer wrap, Galvanic Cathodic Protection, Impressed Cathodic Protection, Re-alkalization, Electrochemical Chloride Extraction, and applying a Penetrating Sealer. Experimental data was obtained concerning properties of the concrete, pore solution, rebar, and environmental conditions within the concrete. Cores were removed for compression testing and pore solution composition analysis. Rebar was also removed for electrochemical testing, including potentiodynamic scans and long-term exposure tests. Semi-permanent probes were inserted to measure environmental properties inside the concrete related to water saturation and oxygen content. Values from these experimental data were then used in the development of numerical models. Simulations and measured data demonstrated low moisture levels and high oxygen content within the concrete were coupled with low/insignificant corrosion rates on the reinforcing metal in most regions. However, measured data suggested high negative half-cell readings could be associated with regions of high concrete moisture (above 60% by volume) due to surface runoff and water pooling on the arches. Numerical modeling and experimental data suggest the relatively low moisture levels within the concrete could be utilized and enhanced to mitigate the corrosion of reinforcing steel. Therefore, building on these conditions, a synergistic mitigation strategy was recommended that incorporated two technologies: discrete Galvanic Cathodic Protection anodes and a Penetrating Sealer. Calculated savings due to this study revealed savings of the order-of-magnitude in the range of $2 to $4 million when compared with alternate rehabilitation strategies. Additionally, the results of the assessment demonstrate the age of a structure has limited bearing on the remaining service life. Rather, if the underlying deterioration processes are controlled or minimized, the life of the element can be extended indefinitely so long as regular monitoring is in place to identify changes in either the environment or condition of the element that would affect the deterioration rates. As such, with the proposed rehabilitation method the City will have a system that with regular monitoring, which is already part of their City wide asset management system, will be easily capable of meeting the desired 50 year service life extension at a minimal cost impact to the overall project.
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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 | 0.007 | 0.007 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.013 | 0.006 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.011 | 0.006 |
| Open science | 0.004 | 0.010 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.010 | 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".