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The development of an effective strategy for the inspection and monitoring of the nation?s critical bridges has become necessary due to aging, increased traffic loads, changing environmental conditions, and advanced deterioration. This article presents the development of a probabilistic mechanistic modeling approach supported by durability monitoring to obtain improved predictions of service life of concrete bridge decks exposed to chlorides. The application and benefits of this approach are illustrated on a case study of a reinforced concrete barrier wall of a highway bridge monitored over 10 years. It is demonstrated that service life predictions using probabilistic models calibrated with selected monitored field data can provide more reliable assessments of the probabilities of reinforcement corrosion and corrosion-induced damage compared to using deterministic models based on standard data from the literature. Such calibrated probabilistic models can help decision makers optimize intervention strategies as to how and when to repair or rehabilitate a given structure, thus improving its life cycle performance, extending its service life and reducing its life cycle cost.

Ultra high performance fibre-reinforced concrete (UHPFRC) is a newly developed concrete material that provides very high strength and very low permeability. The renewal of aging highway bridges and the construction of new bridges using ultra high performance concrete can yield structurally efficient long life bridges, which will require minimum maintenance and low life cycle costs. A simplified flexural design approach of UHPFRC girders and a comparative study of the structural efficiency of UHPFRC and conventional precast prestressed concrete girder bridges are presented in this paper, and to compare its structural efficiency to conventional slab-on- concrete girder bridges. The proposed design approach is consistent with the Canadian Bridge Design Code (CHBDC) and is based on the state-of-the-art design recommendations for UHPFRC and checked using a three-dimensional finite element analysis. It is found that the use of UHPFRC in precast/prestressed concrete girders can yield a reduction of up to two girder lines with smaller girder sizes when compared to conventional concrete girders bridge. UHPC results in a significant reduction in concrete volume that can reach 40%, which turn leads to a more efficient design of the superstructure and a significant reduction in the dead loads on the substructure, which is very important for the safety of aging bridge substructures., 8th International Conference on Short & Medium Span Bridges: 03 August 2010, Niagara Falls, Ontario, Canada

The design and preservation of bridges have been driven, for a long time, by the concerns tominimize costs and improve asset condition. The growing concerns for environmental protection and theshift towards achieving sustainable transportation infrastructure are now requiring the use of approaches thatseek to achieve an adequate balance between social, economic and environmental performance over the entirelife cycle of the bridge. This paper discusses some performance indicators, such as safety, serviceability,costs, traffic disruption, greenhouse gas emissions, which can be used for life cycle design of highwaybridges. An example, taken from the North American context, illustrates how different design and rehabilitation approaches can contribute to achieve the desirable balance between social, economic and environmental sustainability criteria., IABMAS 2010: Bridge Maintenance, Safety, Management and Life-Cycle Optimization: 11 July 2010, Philadelphia, USA

This paper provides an approach based on the monitoring of life cycle performance of concrete bridges exposed to chlorides, and demonstrates its application in a case study. It is first shown that some of the data, which are commonly used by engineers as input values into service life prediction models, can be different from actual field values, because these parameters vary widely in space and time. It is then demonstrated that service life predictions can be improved by updating the models with field monitoring data., 6th International Conference on Concrete under Severe Conditions, Environment & Loading (CONSEC'10): 7-9 June 2010, Mérida, Yucatán, Mexico

This paper presents an approach for a multi-objective-based management of aging critical highway bridges to improve their life cycle performance with emphasis on improving public safety and security. The proposed multi-objective optimization framework is presented as an effective approach that overcomes some of the limitations and complexities of cost-benefit or risk analyses, where all consequences need to be expressed in monetary terms. The framework prioritizes first the critical bridges and then identifies the risk mitigation measures that can be used to satisfy several possible management objectives such as maximizing public safety and public security, minimizing traffic disruption and minimizing costs. Risk mitigation strategies can include more frequent and/or more in-depth inspections, load rating, monitoring of the structural performance and security of bridges, rehabilitation and strengthening of damaged elements, and protection of weak and vulnerable components against extreme shocks due to natural hazards or intentional attacks. A multi-objective criticality index is proposed as a prioritization criterion that achieves an adequate best trade-off between all identified and conflicting objectives. The implementation of the proposed approach is demonstrated on three examples that illustrate the prioritization process on a hypothetical network of ten critical bridges and the use of different risk mitigation measures, such as health monitoring and deterioration prediction models on bridge structures., Aging Infrastructures Workshop: 21 July 2009, Columbia University, New York City

The ageing and deterioration of highway bridges can have serious consequences in terms of reduced safety and serviceability. The objectives of this paper are to present an approach for the structural health monitoring of concrete bridge structures; and to demonstrate the effective use of field monitoring data for the updating of service life prediction models, which accuracy can be significantly improved. A case study on a major highway bridge is also presented and used to illustrate the approach., INFRA 2008: 17 November 2008, Quebec city

A considerable percentage of highway bridges in North America is in a structurally/functionally deficient state due to aging, aggressive environment and increased traffic load and volume. The consequences of this deficiency are numerous, including reduced safety, serviceability and service life, which lead to increased risk of injuries and fatalities; and increased maintenance costs and user costs. Reliable predictions of life cycle performance are critical to the optimization of their design and maintenance that will lead to reduced risks of failure and life cycle costs., Annual Conference of the Transportation Association of Canada (TAC): 21 September 2008, Toronto, Ontario

With its very high strength, high modulus and very low permeability, ultra high performance concrete (UHPC) can provide major improvements over conventional high performance concrete (HPC) in terms of structural efficiency, durability and cost-effectiveness if used in the construction of slab-on-precast prestressed girder bridges. In this study, the optimum use of UHPC is evaluated for the case of simply supported cast in place concrete slab on precast/prestressed UHPC girder bridges. These bridges are designed according to the Canadian Highway Bridge Design Code requirements, including no cracking at the serviceability limit state., Second International Symposium on Ultra High Performance Concrete: 05 March 2008, Kassel, Germany

Workshop on Computational Tools and Technologies for Construction Practitioners: 13 February 2008, London, Ontario

This study investigated the optimum use of ultra high performance concrete (UHPC) for two- and three-lane simply supported bridges. Two designs were investigated: (i) typical cast in place concrete slab on precast/prestressed UHPC girders; and (ii) typical cast in place concrete slab on precast/prestressed UHPC girders. The study measured stress distributions and concentration zones in the girders under dead- and traffic-loads. The concrete quantities and the total areas of prestressing steel were calculated for the UHPC designs and compared to typical concrete designs., 2007 PCI National Bridge Conference: 21 October 2007, Phoenix, Arizona

This paper presents a life cycle-based approach for the design of concrete highway bridges that takes into account physical, economic and environmental performance with emphasis on the reduction of greenhouse gas emissions, construction waste production, and life cycle cost. The analysis considers all the key stages in the life cycle, which include extraction of raw materials, construction, maintenance, repair, rehabilitation, replacement, and disposal. The life cycle analysis compares the life-cycle performance of two concrete highway bridge decks built in corrosive environments - normal concrete is used for one and high performance concrete for the other., 3rd International Conference on Life Cycle Management: 27 August 2007, Zurich, Switzerland

Aussi disponible en français: Pour une meilleure gestion du cycle de vie des tabliers de ponts routiers

Both owners and users of bridges expect them to have a service life of 50 to 100 years, with only routine maintenance. But demands on most of our bridges have been increasing annually because of growing traffic volumes, higher loads, and harsher environments. These conditions, coupled with the inadequate funding allocated for maintenance, have led to the accelerated aging and extensive deterioration of these critical structures.

This paper presents a comprehensive approach to life cycle cost analysis of reinforced concrete bridges that takes into account all costs incurred by the owners and users during construction, maintenance rehabilitation and replacement. This approach provides also an estimate of the environmental impacts associated with construction and replacement of bridge decks in terms of greenhouse gas emissions and waste production. The analysis considers all the key stages in the life cycle, which include extraction of raw materials, construction, maintenance, repair and rehabilitation, replacement, and disposal. The total life cycle costs are evaluated by using the present value method. In this paper, the long-term economic efficiency of high performance concrete (HPC) containing supplementary cementing materials for the construction and rehabilitation of concrete bridges is evaluated and compared to that of normal performance concrete (NPC) in terms of service life, life cycle cost and environmental impacts., Infra 2006 - Le Québec en chantier : optimiser les interventions

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 a new approach for the maintenance optimization of concrete bridgedecks, which combines a stochastic deterioration model and a multi-criteria optimizationmodel. The stochastic deterioration model is based on the first-order Markov chain thatpredicts the probabilistic time-variation of the condition of bridge decks. The multicriteriaoptimization model takes into account two important and conflicting criteria: theminimization of maintenance costs, and the maximization of the network condition. Thisapproach generates the solution that achieves the best compromise between thesecompeting criteria, while considering the uncertainty in bridge deck deterioration. Thefeasibility and capability of the proposed approach is demonstrated on a network ofbridge decks obtained from the Ministère des Transports du Québec database. Thisexample illustrates the effectiveness of the proposed approach in determining theoptimal set of maintenance alternatives for reinforced concrete bridge decks whenconsidering two or more relevant optimization criteria., 7th International Conference on Short & Medium Span Bridges: 23 August 2006, Montreal, QC.

This paper presents a new approach to optimizing the maintenance of concrete bridge decks. This approach combines a stochastic deterioration model and a multiobjective optimization model. The stochastic deterioration model is based on the first-order Markov chain, which predicts the probabilistic time variation of bridge deck conditions. The multiobjective optimization model takes into account two important and conflicting criteria: the minimization of maintenance costs and the maximization of the network condition. This approach achieves the best compromise between these competing criteria while considering the uncertainty in bridge deck deterioration. The feasibility and capability of the proposed approach are demonstrated with field data for a sample network of bridge decks obtained from the Ministère des Transports du Québec database. This example illustrates the effectiveness of the proposed approach in determining the optimal set of maintenance alternatives for reinforced concrete bridge decks when two or more relevant optimization criteria are taken into consideration.

Aussi disponible en français: De nouveaux outils d'aide à la décision facilitent la gestion du cycle de vie des tabliers de pont en béton

This paper presents an approach for bridge maintenance optimization that takes into account several and possibly conflicting criteria, with emphasis on risk of failure as a governing criterion. The optimal maintenance strategy is defined as the solution that achieves the best compromise between three selected relevant and conflicting criteria: minimization of risk of failure, minimization of maintenance costs, and minimization of traffic disruption. Compromise programming is used to determine the optimal ranking of the maintenance strategies in terms of their effectiveness in risk reduction, cost minimization, and traffic control. A multi-criteria optimality index is proposed as a measure of the effectiveness of the optimal maintenance strategy in achieving a satisfactory trade-off between the above relevant and competing maintenance criteria. The proposed approach is illustrated on a small network of ten bridge projects that are optimized for maintenance by considering the three selected criteria. The weighted and non-weighted multi-criteria indices are generated for these projects., 2nd International Colloquium on Advanced Structural Reliability Analysis Network (ASRANet), Organized by International Center for Numerical Methods in Engineering: 05 July 2004, Barcelona, Spain

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 presents a two-level approach for the maintenance management of aging highway bridges that integrates two different probabilistic deterioration prediction models. The level-1 management is based on Markovian cumulative damage models that predict the macro-response of bridge structures. The level-2 management is based on quantitative reliability-based mechanistic deterioration models that predict themicro-response of bridge structures. The level 1-management identifies the critically damaged structures and forecasts the overall deterioration and required maintenance funds for both short and long term planning for a bridge network or a bridge component. The level-2 management focuses on the critical structures that were identified from the level-1 management or from a specific condition assessment to evaluate their safety and serviceability, and optimize their maintenance. The proposed two-level approach to bridge maintenance management, which integrates two different probabilistic deterioration models, will help improve the effectiveness of maintenance management systems in satisfying the safety, serviceability, andbudgetary requirements of highway agencies., 7th ASCE International Conference on Applications of Advanced Technology in Transportation: 05 August 2002, Boston, MA., U.S.A.

Bridge management systems (BMSs) are developed to assist decision-makers in optimizing the allocation of their limited budget on maintenance needs of bridge networks. Reliable deterioration models are essential constituents of BMSs that are used to predict the remaining service life of bridge components. The deterioration models incorporated in the recent BMSs have limitations that can be accepted for the analysis at the network level but not at the component level. Moreover, the current mechanisticdeterioration models developed for the component level analysis are neither versatile nor adequately extensible to predict the service life of a large number of bridge components, or to incorporate additional deterioration parameters. Therefore, an artificial intelligence approach 'Case-Based Reasoning (CBR)' is proposed to develop extensible, reliable, and generic deterioration models for the analysis at the component level. The CBR approach is utilized to predict the time to corrosion initiation of the reinforcing steel inconcrete bridge decks. Data obtained from the Dickson Bridge in Montreal are used to generate the cases that populate the case library of the CBR model by applying the Monte Carlo Simulation techniques. Parameters that significantly affect the deterioration rate of concrete decks, such as the concrete cover thickness, apparent diffusion coefficient, and surface chloride concentration, are considered., 6th International Conference on Short and Medium Span Bridges: 31 July 2002, Vancouver, B.C.

Many transportation agencies have recently adopted bridge management systems (BMSs) tooptimize decisions related to the expenditure of their limited funds on bridge maintenance,rehabilitation, and replacement (MR&R). The analysis in most of these BMSs is based on thelife-cycle assessment of different MR&R alternatives for a network of bridges. This assessmentrequires reliable prediction of the condition of different bridge components when various MR&Ractions are implemented (including the 'do nothing' option). The state-of-the-art systemsconsider the use of the stochastic Markov chain models in predicting the bridge performance.This stochastic approach can predict the condition of a bridge component at any time usingpredefined transition probabilities obtained by expert judgment elicitation procedures. In thispaper, the actual condition data obtained from the Ministére de Transport du Québec (MTQ) areused to develop transition probabilities for concrete bridge decks. These probabilities areemployed to validate those developed based on the literature and engineering judgment. Inaddition, a subset of the data is utilized to validate the state independence assumption of Markovchains., Proceedings of the 2002 Taiwan-Canada Workshop on Bridges: 08 April 2002, Taipei, Taiwan

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

Aussi disponible en français: En bref - un logiciel d'aide à la décision pour estimer la durée de vie utile et planifier la réhabilitation des tabliers de pont en béton

This paper presents a probabilistic approach to life prediction of concrete highway bridge decks based on Bogdanoff''s cumulative damage model. The condition of the deck is discretized into a finite set of damage states including no damage, onset of corrosion, crack initiation, major damage and failure. The damage accumulation process is modeled using a stationary unit jump Markov chain in which the probability distribution of damage after a duty cycle is assumed to depend only on the length of the duty cycle and the damage accumulated at the start of the cycle. The service life is determined from the time to reaching the absorbing state, which may successively be redefined as the onset of corrosion, cracking, spalling, etc. The proposed model is simple to use and the statistics of the lifetime and damage states at any given time are easily determined. The model yields a practical tool for the condition assessment, life prediction, and maintenance management of highway bridge decks. An example illustrating the application of the proposed approach is presented., Proceedings of International RILEM Workshop on Life Prediction and Aging Management of Concrete Structures: 16 October 2000, Cannes, France

Aussi disponible en français: En bref - Un consortium se penche sur la question de l'entretien des ponts en béton

CERIU-Infra 99 International Convention: 22 November 1999, Montreal, Quebec

Developments in Short and Medium Span Bridge Engineering '98: 13 July 1998, Calgary, Alberta