Notice bibliographique
Résumé
This presentation is meant to provide an overview of the ultra-high performance concrete (UHPC) bridge activities and projects since the First International Interactive Symposium on Ultra-High Performance Concrete which took place in Des Moines, Iowa in 2016.Since then, over135additional bridges have been constructed using UHPC bringing the total number of projects in North America to over 280 bridges. The years prior to 2016 were largely dominated by precast deck panel projects with UHPC connections in the New York State region of the U.S. and by adjacent box beam projects with longitudinal UHPC connections in Northwestern Ontario. Since 2016, the Northeastern region of the U.S. (i.e. New York, New Jersey, Pennsylvania, Delaware, etc.) continue to regularly utilize UHPC on their projects. Additionally, there has been growing interest in the Western U.S. (i.e. California, Idaho, Colorado, Oregon)and the Southeast (i.e. Florida, Georgia, South Carolina). The figures below show the number of completed bridge projects with UHPC by year (left) and the locations of these projects(right). The state of Idaho, in particular,has seen substantial activity since standardizing UHPC connections for two of their superstructure types (i.e. deck bulb-tees and solid/voided slab beams). The Idaho Transportation Department (ITD) has replaced over ten (10) bridge superstructures with UHPC since 2016, with more in the pipeline for 2019 and beyond. The Iowa DOT has also standardized UHPC connections for their adjacent box beam structures and is letting an 8 to 14 bridge replacement package in 2019. While precast deck panels and adjacent box beams are still popular applications, there has been a notable increase in other superstructure types such asdeck bulb tees, next beams, voided slabs, and prefabricated bridge units (PBUs) with longitudinal UHPC connections. These systems have become popular, particularly for shorter span structures, as a means to rapidly replace existing deteriorated superstructures using the Accelerated Bridge Construction (ABC) methodology. In conjunction with these ABC systems has been an increasing demand for high early-strength UHPC mix designs for closure pour connections. Accelerated UHPCs (e.g. Ductal®JS1212)can attain design compressive strength (typically 14 ksi) in 24-36 hours compared to non-accelerated UHPCs (e.g. Ductal®JS1000)which require 4 days or more to attain this strength. Accelerated UHPCs tend to have a reduced working time, but work well for these ABC superstructure replacements due to the small quantity of UHPC required and the small placement size needed to complete the connection. There has also been an emergence of newer UHPC applications,including substructure connections, link slabs, joint headers, bridge deck patching, and thin-bonded structural overlays. The overlay application, in particular,has been implemented on four bridge projects in the U.S. since 2016 (a solution that is regularly implemented on bridges in Switzerland) and has generated much interest as a means to rehabilitate existing structures and provide long-term protection tonew bridge decks. Lastly, the past few years have also seen an emergence of several new UHPC standards in North America, including 1) the ASTM C1856materials testing standard, 2) the FHWA Checklist for UHPCConnections,3) a 2019 update to the FHWA TechNote on the Design and Construction of Field-Cast UHPC Connections, 4) the AASHTO LRFD Guide Specification for Accelerated Bridge Construction (which includes commentary on UHPC connections), 5) the ACI Emerging Technology Report on UHPC, and 6) the CSA Standards in Canada to be published in 2019. This presentation will highlight the above bridge-related activities in North America and showcase a handful of completed projects since the 2016 symposium including the 3-mile long Pulaski Skyway re-decking project in New Jersey, the new cable-stayed bridge in Nipigon, Ontario, and the multi-span superstructure replacement in Bath, Maine. The presentation will close with a brief discussion on what’s to come in the years ahead.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,002 | 0,005 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,003 | 0,005 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,003 | 0,003 |
| Science ouverte | 0,001 | 0,003 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,011 | 0,004 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».