Geneva St Ramp: Replacement of Steel Girder Bridge with Post-Tensioned Concrete Structure on Existing Foundations
Bibliographic record
Abstract
<p>The ramp was built in 1963 as part of the original Hwy 406 south of St. Catharines. The existing bridge consisted of five simply supported spans of 22.6 m, each supported by two steel plate girders composite with a concrete deck. The ramp was regularly maintained through the years: a waterproofing membrane was added in 1979 along with sealed expansion joints, and the expansion joints replaced again in 1998. In 2015, the condition of major components had deteriorated significantly and coupled with concerns for redundancy and structural steel details vulnerable to constraint induced fracture (overlapping welds), led to the decision to replace the superstructure.</p><p>The ramp has complex geometry consisting of a tangent, a radial curve and two spirals in plan, a longitudinal grade increasing up to 5%, and the 9.35 m cross-section has variable superelevation. The ramp spans over a valley. After considering several alternatives (including filling in the valley), a post-tensioned concrete solid slab deck of 0.7 m thickness was selected for the replacement superstructure. The new deck is 0.8 m wider and 20% heavier than the steel superstructure it replaces. The geotechnical engineer reanalysed the steel pile foundations with current practices and found potential to increase capacities, later confirmed through additional boreholes.</p><p>The deck is supported on four slender piers monolithic with the deck, and on the existing abutments where semi-integral deck ends support the wingwalls and approach slabs. The reuse of foundations was a defining feature of the project, key to the success of the selected alternative, saving time and cost in construction. Construction of the bridge started in July 2021 and was completed in September 2022. The project demonstrates that post-tensioned concrete bridges can be built competitively with girder bridges and contribute to sustainability.</p>
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".