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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.

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

Aussi disponible en français: Cadre de travail modèle pour l'évaluation des infrastructures publiques de base au Canada

8th TRB National Conference on Transportation Asset Management: 19 October 2009, Portland, OR

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

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

High performance concrete (HPC) bridge decks are prone to premature cracking if movement is restrained. Internal curing (IC) can reduce shrinkage cracking in structures, thus improving their performance and service life. However, there is very limited information in the literature on the possible extension of service life due to internal curing. This paper addresses this question by using predictive models to estimate the service life and life-cycle costs of a typical bridge deck made with concrete using internal curing as opposed to conventional curing. Four options are compared: (i) normal concrete deck; (ii) HPC deck; (iii) HPC deck with internal curing; and (iv) very high performance concrete deck with internal curing. It was found that the use of internal curing can extend the service life of HPC bridge decks by almost ten years, which is mainly due to due a slower penetration of chlorides as a result of reduced shrinkage cracking. The use of internal curing in HPC decks resulted in a 20% reduction in life-cycle costs, even though the in-place unit cost of internally-cured HPC can be up to 4% higher than that of conventionally-cured HPC. The higher initial investment for the construction of the HPC-IC deck can be offset in only 5 years when compared to that required for normal concrete deck. This is due to a longer service life and less frequent maintenance activities., 50th Brazilian Concrete Congress "Concrete Infrastructure and Environmental Conservation": 04 September 2008, Salvador, Brazil

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

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

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

In August 2000, a concrete pipe culvert of 1370mm inside diameter was installed under a truck route in the former Regional Municipality of Ottawa-Carleton (now City of Ottawa) using the Standard Installations method. The project demonstrated two installation conditions, known as Type 2 and Type 3. In order to evaluate the pipe performance and verify the Standard Installations theory, two (2) pipe sections were instrumented to evaluate the loading conditions and enable a comparison of the Standard Installations theory. The performance monitoring conducted over a three-year period showed good correlation with the Standard Installations theory. The measured performance of the pipe from the test site compared to the predicted performance for Standard Installations has resulted in some very informative findings on the interaction between pipe and soil, and provides the owners of infrastructure with design options for concrete pipe. This research offers a cost effective alternative to the current design method developed more than seventy years ago., 33rd Annual General Conference of the Canadian Society for Civil Engineering, June 2, 2005, Toronto, Ontario, Canada

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

Aussi disponible en français: En bref - L'IRC lance un projet de recherche sur l'analyse du cycle de vie et la durabilité des structures en béton à haute performance (BHP)

Sliplining is one of the trenchless technologies that can be used in the rehabilitation of an underground pipe. Typically the annular space between the host pipe and the liner is grouted. Common practice is to design the liner pipe to withstand full internal and external loads, without considering the structural contributions from the existing host pipe and from the grout. This over-simplified practice is followed partially because the behaviour of grouted sliplined pipes and the roles that the pipes and grout play in such a system are not well understood. This paper presents some insight into the behaviour of grouted sliplined pipes with the results of a numerical (finite element) analysis on the effects of eccentricity between the liner and host pipe and bonding at the pipe interfaces. This study shows that the direction of eccentricity between the liner and host pipe in a grouted sliplined pipe has a significant impact on the behaviour of the pipe with unbonded interfaces (a pipe-within-a-pipe system), or with bonded interfaces (a composite pipe). Vertical eccentricity (i.e. in the vertical plane) results in an increase in stress in the host and the liner pipe, whereas horizontal eccentricity results in an increase in stress only in the liner pipe. Sliplined grouted pipes with bonded interfaces are subject to less stress than pipes with unbonded interfaces. Furthermore, horizontal eccentricity has the effect of reducing the vertical ring deflection of pipes with or without bonded interfaces.

Utility contractors will increasingly encounter a new method for rehabilitating buried pipelines (water, sewer and gas). It's called sliplining and it involves pushing and/or pulling a new liner pipe into a failing, existing pipe. Except for the need for access pits at intervals along the route of the pipe, excavation is not required. The technique, therefore, offers many advantages over traditional open-cut and cover methods - less traffic disruption, less disturbance to the environment, and less annoyance for the public.

Annulus grouting, or non-grouting, is often the question in the minds of municipal engineers when considering trenchless sliplining technique for pipe rehabilitation. For ease of installation in sliplining rehabilitation, the outside diameter of the liner pipe is usually at least 10% smaller than the inside diameter of the host pipe, resulting in an annular space (or annulus) between the two pipes. Currently the decision on annulus grouting is mainly based on its impact on construction and cost. Based on a three-year study on the performance of a sliplined water main in the City of Ottawa, the effect of the grout on the performance of slipline pipe is presented in this paper. The pros and cons are explained in terms of buckling resistance, potential shear failure at lateral connections, protection of liner pipe when the host pipe fails, load-carrying capacity and control of load-sharing. Furthermore, how grouting can be used to maximise the desired performance of slipline pipe, or to strengthen an existing culvert is suggested in thepaper. This paper fits well with the theme of INFRA 2003 as it shares proven solutions to sliplining rehabilitation and promotes innovation in construction to maximize pipe performance., Infra 2003: the Changing Infrastructure Rehabilitation Market: the Emergence of a New Dynamic, 17 November 2003, Montréal

La réhabilitation ou le remplacement des ponceaux est un sujet qui préoccupe de plus en plus les propriétaires de ces ouvrages. Une collaboration entre l'Institut de recherche en construction (IRC), l'Association des tuyaux de béton de l'Ontario (OCPA) , le Ministère des Transports de l'Ontario (MTO) et la Ville d'Ottawa a permis de réaliser le suivi du comportement des conduites de drainage en béton installées selon la méthode «Standard Installations Direct Design» ou SIDD au lieu de la méthode traditionnelle de Marston-Spangler. Le projet, débuté à l'été 2000 et d'une durée de trois ans, avait pour objectif de vérifier, sur le terrain, la distribution des pressions du sol autour de la conduite ainsi que les contraintes dans la paroi de la conduite. Pour ce faire, deux sections de conduites, installées selon le Type 2 et Type 3 de la méthode SIDD, ont été instrumentées à l'aide de cellules de pression et de jauges de déformation reliées à un système de collecte de données automatisé. Les mesures obtenues sont comparées aux diagrammes de distribution de pression et aux contraintes maximales proposées par Heger qui constituent la base de la méthode SIDD. Les résultats démontrent, que pour les deux types d'installations étudiés, les pressions mesurées se comparent raisonnablement à celles obtenues par la méthode SIDD.Quant aux valeurs des contraintes dans la conduite, les mesures de terrain sont généralement assez proche des valeurs de moments proposées par la méthode SIDD. Un résumé des caractéristiques des méthodes SIDD et Marston-Spangler est aussi présenté., Infra 2003 : L'évolution du marché de la réhabilitation des infrastructures : une nouvelle dynamique s'impose: 17 November 2003, Montréal

Aussi disponible en français: Des chercheurs de l'IRC définissent un critère de qualité pour la fusion bout à bout des conduites en PEHD

Vibrating-wire earth pressure cells are often used to measure soil pressure in fills and embankments or contact pressure between soil and buried structures. The cell consists of two metal plates welded on their periphery and filled with oil. Changes in applied pressure result in variations in fluid pressure in the cell, which is detected by a transducer, one type of which is the vibrating wire. The vibrating wire pressure cell is commonly used due to its long-term reliability. Geotechnical instrumentation companies provide each cell with a formula to calculate pressure based on frequency and temperature readings. Small diameter (76 mm) pressure cells installed in the field, around and in the vicinity of a concrete culvert, were responding in a manner that seemed to be strongly affected by temperature variations. Laboratory work was subsequently done to confirm the behaviour of the cells. Temperature calibration work was carried out for a series of 76 mm diameter cells and several 228 mm cells. The calibration was run with temperatures ranging from -10°C to 30°C with and without the effect of applied pressure on the cells. From this work, and from data gathered from different field sites, it was found that temperature calibration factors, given on the manufacturer's calibration sheet specific to each cell, largely underestimated the temperature effect. It was also found that the correction factors were dependent not only on temperature, but also on the pressure applied to the cell. The results showed that the temperature calibration curve, given as a linear correction on the calibration datasheet, became parabolic as pressure was applied to the cell. Recommendations are provided for minimising the temperature effect on sensitive pressure cells as well as for more accurately correcting temperature effects on cell readings. In addition, suggestions for improvement in the manufacture and calibration of pressure cells before they are installed in the field are presented., On utilise souvent des cellules manométriques à fil vibrant pour mesurer les pressions du sol dans les remblais et les endiguements ou la pression de contact entre le sol et les ouvrages enfouis. Les cellules sont formées de deux plaques métalliques soudées sur leur pourtour et remplies d'huile. Les variations de la pression appliquée se traduisent par des variations de pression du liquide contenu dans la cellule. Ces variations sont décelées par un transducteur, qui peut être un transducteur à fil vibrant. On utilise beaucoup les cellules manométriques à fil vibrant, car ces appareils sont très fiables pour un usage prolongé. Les entreprises d'instruments géotechniques fournissent avec chaque cellule une formule permettant de calculer la pression à partir des lectures de fréquence et de température. Les cellules manométriques de faible diamètre (76 mm) installées sur le terrain, autour et à proximité d'un ponceau en béton ont réagi d'une manière qui semblait indiquer une forte sensibilité aux variations de température. On a effectué par la suite des travaux de laboratoire pour confirmer le comportement des cellules. On a procédé à l'étalonnage de la température sur les cellules de 76 mm de diamètre et plusieurs cellules de 228 mm. L'étalonnage a été effectué pour des températures de -10 à 30 °C avec et sans l'effet de la pression appliquée sur les cellules. À partir de ces travaux et des données recueillies aux différents emplacements, on a constaté que les facteurs d'étalonnage de température indiqués sur la fiche d'étalonnage du fabricant pour chaque cellule sous-estimaient de beaucoup l'effet de la température. On a également observé que les facteurs de correction dépendaient non seulement de la température mais aussi de la pression appliquée sur la cellule. Les résultats montrent que la courbe d'étalonnage de température, représentée sous forme de corrélation linéaire sur la fiche technique, devenait parabolique lorsqu'une pression était appliquée sur la cellule. On formule des recommandations pour réduire l'effet de la température sur les cellules manométriques sensibles et pour corriger avec une plus grande précision les effets de la température sur les lectures. On donne par ailleurs des suggestions pour améliorer la fabrication et l'étalonnage des cellules manométriques avant que celles-ci ne soient installées sur le terrain.

Butt fusion is an effective method for joining high density polyethylene (HDPE) pipe on job sites. However, there is lack of no quantitative methods to evaluate pipe joint quality. The objective of this study was to develop such a quantitative approach in order to determine the effect of joint contamination on the quality of the fused joints. The study included testing a total of 21 butt-fused HDPE pipe joints that were made under different dust conditions. The results of the tests were then used to determine the effect of dust contamination on the quality of the fused joints. Microscopic examination of the fracture surfaces of the test specimens showed that not all the contaminants at the welding interface were squeezed out into the beads formed during the fusion process. Four failure modes were identified and a failure criterion was established to categorize the quality of a fused joint into four grades ' bad, poor, good and excellent. Among the properties of the materials considered, tensile energy to break (TEB) and maximum strain were found to be the most acceptable parameters for distinguishing between different quality of joints. Furthermore, the results showed that under optimum joining conditions, the quality of butt-fused joints can be as good as that of the parent pipe.

This paper presents the measured mechanical and thermal performances of an HDPE sliplined cast iron watermain based on two and a half years of monitoring. The data were acquired from strain gauges installed on the host cast iron pipe and on the new HDPE pipe to monitor the short- and long-term field performance of the HDPE sliplined watermain., No-Dig 2002: 28 April 2002, Montreal

Rehabilitation of a watermain by grouted sliplining is usually carried out when the existing pipe is only par-tially deteriorated. Although designs that neglect the structural contributions from the existing pipe and the grout are generally conservative, the performance of the rehabilitated pipe needs to be better understood for effective design and management of buried water pipes. Presented in this paper is a practical method for the determination of load sharing and circumferential stresses in a sliplined pressure pipe. The laboratory tests show that the load carrying capacity of a cast iron pipe increases substantially after it is sliplined and grouted. Results also indicate that the eccentricity between the host pipe and the inserted pipe and the direction of eccentricity have an impact on the rupture load of the sliplined pipe. The effects of the host pipe wall thickness and the grout strength are also discussed. Although the method is based on a pressurized watermain, it can be used to assess the load carrying capacity of a non-pressurized pipe such asa sewer pipe. The use of this method is demonstrated through an example.