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The need to upgrade the large number of aging reinforced concrete (RC) structures that are exposed to aggressive environments, such as de-icing salts in cold regions and sea water requires the development of innovative solutions that will lead to the construction of long life RC structures with low life cycle costs. In this paper, the impacts of using high performance reinforcing steels (HPS), such as 316 LN, 304 and 2205 duplex stainless steels and ASTM - 1035 (or chromium) steel on the service life and structural behaviour of RC structures are investigated. In terms of resistance to chloride attack, 316 LN stainless steel provided the highest value, followed by 2205 duplex steel, chromium steel and then carbon steel. In terms of yield and ultimate strengths, chromium steel exhibited the highest values followed by 316 LN and 22065 duplex steels then carbon steel. In terms of ductility, the RC beams reinforced with 316 LN steel exhibited the highest capacity to deform before fracture, followed by duplex 2205 steel, carbon steel, and then chromium steel. In terms of flexural design of RC beams reinforced with HPS, the same flexural capacity is achieved by using much lower areas of reinforcement for chromium steel, followed by stainless steel and then carbon steel. This suggests that greater savings in material, labour, and maintenance costs are possible when using chromium steel and stainless steel as a reinforcement for RC structures built in aggressive environments, such as highway bridge decks, parking structures, marine and offshore structures., 3rd Congress of the International Federation for Structural Concrete (FIB) and PCI Convention: 29 May 2010, Washington, D.C.

The ageing and deterioration of highway bridges can have very serious consequences in terms of reduced safety, serviceability and functionality. Many bridges built in the 1960's and 1970's are considered deficient by today's standards. The widespread deterioration and some recent failures have highlighted the importance of developing and implementing effective inspection strategies, including structural health monitoring systems, which can identify structural problems before they become critical and endanger public safety. Continuous monitoring is becoming necessary due to ageing of bridges, increased traffic loads, changing environmental conditions, and reduced capacities, especially for medium and long-span bridges given the severe consequences of failure. The implementation of monitoring programs can assist in optimizing the in-depth inspection, maintenance, rehabilitation, and replacement of bridge structures. The continuous and simultaneous measurements at critical discrete points of a bridge system will allow the assessment of its performance with respect to different limit states, including safety and serviceability. Prediction models, updated from such monitoring data, can optimize intervention strategies as to how and when to repair or rehabilitate thus extending service life and reducing life-cycle costs.The objectives of this paper are: (i) to present an approach for the efficient use of structural health monitoring into the durability and structural reliability assessment process; (ii) to highlight the applicability of the approach to short, medium and long-span bridges; and (iii) to demonstrate the effective use of field monitoring data for the calibration and updating of service life prediction models. A case study on a medium-span concrete highway bridge is also presented and used to illustrate the approach., 4th International Conference on Structural Health Monitoring of Intelligent Infrastructure (SHMII-4): 22 July 2009, Zurich, Switzerland

ACI Workshop on Advances in Service Life Models that Consider Multiple Sources of Deterioration, 24 April 2007, Atlanta, Georgia

Cet article présente deux différents types de modèles fiabilistes pour la prévision de la durée de vie des tabliers de ponts en béton qui permettent une gestion efficace de la maintenance des ouvrages d'art. Le premier modèle est de type mécano fiabiliste où la performance physique de la dalle est décrite par une fonction appelée marge de sécurité, qui mesure la différence entre la résistance de la dalle et les effets des charges mécaniques et/ou environnementales sur la dalle. Ce type de modèle est utilisé pour prédire la variation avec le temps de la probabilité de défaillance de la dalle. Les différents temps pour atteindre les différents états de défaillance correspondant à différents états limites peuvent être prédis incluant les états de corrosion des armatures, fissuration, délaminage, éclatement du béton d'enrobage, et rupture. Un autre type de modèle qui prédit l'accumulation de l'endommagement de la dalle comme un processus stochastique a été développé. Dans ce modèle, la durée de vie de la dalle est prédite comme le temps ou l'état absorbant est atteint. L'intégration de ces deux modèles permettra une gestion optimale des tabliers de ponts, Also published in "Recueil des Commuications du 13e Colloque sur la Progression de la Recherche sur les Ouvrages d'Art, Transports Québec, Québec, QC. May 9, 2006, Infrastructures durables: Techniques, outils et guides, Regard sur la science du bâtiment 2006, 1 October 2006

This paper presents an approach to programming maintenance alternatives for a network of concrete bridge decks using genetic algorithms and Markovian performance prediction models. Genetic algorithms are robust and stochastic optimization techniques that overcome the mathematical complications and combinatorial explosion problems of the conventional optimization techniques. Markovian models are the state-of-the art stochastic models used in several maintenance management systems to predict the future condition for a network of infrastructure facilities. An illustrative example for finding the optimal maintenance alternatives for concrete bridge decks using field data is presented to demonstrate the feasibility and capability of the proposed approach., Annual Conference of the Canadian Society for Civil Engineering, 4 June 2003, Moncton, N.B.

This paper provides an overview of the development of software-based decision support tools for service life prediction and rehabilitation of corrosion-damaged concrete bridge decks. The proposed tools consist of a reliability-based service life prediction model and a life cycle costing model that will assess the impact of alternative rehabilitation strategies on extending the life of bridge decks and their costs., Supersized Session on Asset Management, APWA International Public Work Congress: 08 September 2001, Philadelphia, PA

Proceedings of the Third International Conference on Concrete under Severe Conditions: Environment & Loading: 18 June 2001, Vancouver, B.C.