In the early 90's a breakthrough technology called Ultra-High Performance Concrete was being introduced to the bridge community as a new technology that could revolutionize bridge design and construction. The new material technology offered very durable new solutions, but required, new shapes, new design codes & standards, new precast fabrication methods and formworks. The new technology immediately met enthusiasm for use; however there were several barriers to entry as mentioned above. Bridge owners saw the value and so did bridge consultants; however the lack of design standards created increased risk to both owners and designers - a dilemma. This paper explains briefly the technology, applications, the risks of the owners and designers in using it, and how these risks were mitigated to develop innovative solutions.

This work presents a model-based analysis of the risk of early age cracking in structures made of Ultra High Performance Concrete (UHPC). First, we summarize the background works on modelling UHPC at early age with emphasis on the thermodynamics hypothesis of partial decoupling which substantially simplifies the application and calibration of the model. Then, after calibrating the chemo-thermo-mechanical properties, we present two case studies: the UHPC footbridge in Calgary, Canada, and the “Passerelle des Anges” close to Montpellier, France. The comparison between the simulated and measured histories of temperature and strains is presented. The concept of level of loading was employed to assess the risk of early age cracking. Finally, a probabilistic analysis of a simplified 1D case is employed to support the final conclusions. Résumé On présente le travail de modélisation réalisé pour analyser le risque de fissuration au jeune âge d’ouvrages réalisés en bétons fibrés à ultra-hautes performances (BFUP). On résume d’abord les travaux précédents sur la modélisation du BFUP au jeune âge en insistant sur l’hypothèse de découplage thermodynamique partiel qui simplifie grandement la mise en œuvre et la calibration du modèle. Puis, après ajustement des paramètres thermo-chimicomécaniques, on présente deux études de cas : une passerelle en BFUP à Calgary, Canada, et la passerelle des Anges près de Montpellier, France. On compare les histoires de température et de déformations simulées et mesurées. Le concept de degré de chargement a été utilisé pour estimer le risque de fissuration au jeune âge. On réalise enfin une analyse probabiliste sur un exemple unidimensionnel simplifié pour étayer les conclusions finales. CONCRACK 3 – RILEM-JCI International Workshop on Crack Control of Mass Concrete and Related Issues Concerning Early-Age of Concrete Structures, 15-16 March 2012, Paris, France 212

This article describes a promising new material called Ductal for use in bridges. Ductal is an ultra-high performance, fiber-reinforced cement composite material. It offers superior technical characteristics (including ductility, strength and durability) while providing highly moldable products with a high-quality surface aspect. This unique combination of properties allows designers to create thinner sections and longer spans that are lighter, more graceful and more innovative in geometry and form while providing improved durability and impermeability. Compressive strengths for bridge applications range up to 30,000 psi, with flexural strengths of up to 6,000 psi. The first industrial use of Ductal was a pedestrian bridge in 1997. Since then, several pedestrian bridges have been constructed successfully using Ductal. The Federal Highway Administration is currently investigating Ductal as a possible solution for the replacement of deteriorating highway bridges. One challenge facing highway bridge engineers is how to design bridges using this technology when current design codes and standards do not provide guidance. In response, several international groups have developed interim design guides. Optimized shapes and profiles for each use also need to be developed so that the industry can invest in the appropriate formworks to produce optimized pieces. Once these obstacles are overcome, the true merits of Ductal for bridge engineering can be fully recognized.

In the first issue of each year we thank the volunteers who are responsible for maintaining the integrity and quality of the peer-reviewed papers published in PCI Journal. They are selected from the rosters of relevant PCI or ACI committees, our author database, and the references of the manuscripts we ask them to review. Many active members of PCI, as well as other knowledgeable people from around the world, participate in this vital service to the industry. To encourage objectivity and free expression, reviewers of PCI Journal manuscripts are anonymous to the authors and to one another. They spend hours on top of their regular jobs evaluating in detail the merits of the unedited manuscripts we send to them, giving all of us the benefit of their specialized expertise. Our heartfelt thanks to everyone who did so in 2014.