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Bridge infrastructure assets should be planned, designed, constructed, and operated to account for the physical processes that may occur over their service lives. In ice-affected rivers, this includes the interaction of bridge infrastructure with river ice. Advancements in river-ice science and modelling of ice processes in ice-covered rivers have enhanced the abilities of civil/hydrotechnical engineers to plan, design, and construct bridges in and along rivers with seasonal ice covers. In this paper, an overview is presented of ice-related considerations with respect to bridges. The bottom-chord elevation of the bridge superstructure with respect to water and ice levels, pier design to withstand ice forces, the waterway opening for ice passage, ice-induced scour, and research needs are discussed. However, as outlined in the paper, research on ice loads and passage at bridge sites and on hydroclimatic and ice conditions that led to bridge damage and failure remains needed. [ABSTRACT FROM AUTHOR]

Between the 2006 and 2014 editions of CSA S6, significant changes were made to the simplified method of analysis (SMA) for all girder bridges, including transverse wood deck on wood girder bridges. The load-distribution predictions became more conservative, resulting in both load-limit posting of existing bridges and increased cost for bridge construction, repair, and replacement. In this paper, we examine the load distribution for the timber bridge inventory in NS. Finite-element models are developed and rigorously validated; a parametric study, consisting of 204 bridges, is performed; current SMA equations are evaluated; and new equations for the truck-load distribution width are derived. The new equations bring SMA predictions of the longitudinal bending moment for transverse wood deck on wood girder bridges into line with currently expected safety-index levels. Corrected bias factors and coefficients of variation for live-load analysis/evaluation in conjunction with CSA S6 are presented. [ABSTRACT FROM AUTHOR]

Single-mode spectral analysis (SMSA) is a simple procedure efficiently used to evaluate the seismic demands of base-isolated bridges, particularly suitable for the design of simple bridges or preliminary design of complex bridges. However, bridge design codes, notably the Canadian code CSA-S6:19 (CSA-S6 2019), specify many limitations on the use of the method for final design. This paper evaluates the performance of SMSA and the efficiency of its limits of application as specified in the current codes through the results of a parametric study. The hysteretic properties of seismic isolation systems and the stiffness of bridge substructures are varied. Seismic demands predicted by SMSA and nonlinear time-history analyses (NLTHAs) are then compared, both inside and outside the current specified limit range in CSA-S6:19 (CSA-S6 2019). Results show that the most effective application conditions are those related to the maximum equivalent viscous damping and minimum restoring force. The upper limits of the effective period and the post-elastic period can be ignored. Further, to complement SMSA, a relation is proposed to estimate the expected residual displacement as a function of the restoring force at the design displacement. Regression relations allowing estimating the expected mean and confidence interval of the relative displacement deviation predicted by SMSA from that based on NLTHA are also proposed. [ABSTRACT FROM AUTHOR]

The Canadian Highway Bridge Design Code (CHBDC) uses the concept of a target reliability index for evaluating the load carrying capacity of existing bridges. This index, which is based on risk to human life, relates to three aspects of uncertainties inherent in a bridge: (a) element behaviour, (b) system behavior, and (c) inspection level, where the inspection level currently refers to only manual inspections. Citing examples of tests on many instrumented bridges, the paper proposes an additional inspection level for inspections done with the help of electronic instruments and tests under controlled vehicle loads. The paper proposes simple additions to clauses of the CHBDC, for use when determining the optimum load carrying capacities of existing bridges where structural health monitoring information is available. [ABSTRACT FROM AUTHOR]

Military vehicles are sometimes required to transit bridges owned and operated by civilian bridge authorities. Using available data regarding the gross vehicle weight and associated axle loads of military traffic, live load factors, calibrated to the Canadian Highway Bridge Design Code, are proposed for bridge design and evaluation. This paper recommends live load factors for three categories of military vehicles: (i) wheeled-transport vehicles; (ii) wheeled-fighting vehicles; and (iii) tracked-fighting vehicles. The values are derived for interior girders of simply supported slab-on-girder bridges subjected to a single lane of traffic loading and are believed to be generally applicable for other structural elements and bridge types. Inherent differences between fighting vehicles, which are heavily armoured, and transport vehicles, which although armoured have high payloads, suggest that highway bridges should be evaluated separately for military fighting vehicles and military transport vehicles using distinct live load factors. [ABSTRACT FROM AUTHOR]

This paper describes the development of a unique rolling load simulator (ROLLS) for testing bridge superstructure with a footprint up to 4 m ×17 m, and its first application to test a full-scale 1220 mm ×900 mm ×16000 mm B900 prestressed concrete box girder. This facility at Queen's University in Kingston, Ontario, is the first of its kind in Canada. ROLLS can apply cyclic loading in a controlled laboratory environment, under realistic highway scale 'rolling wheel loads', in lieu of the conventional 'pulsating stationary loads'. It has two half-axles of a large tandem, each comprising a dual 1140 mm diameter air-inflated tires spaced at either 1.2 or 2.4 m. Each half-axle can apply up to 125 kN, representing the heaviest half-axle load of the CL-625 design truck of the Canadian Highway Bridge Design Code (CHBDC). The maximum travel range and speed are 14.9 m and 6 m/s, respectively. A case study involving analysis of a bridge with eight adjacent B900 box girders of 27.6 m span was carried out prior to experimentally testing one of the girders using ROLLS. Load distribution analyses were conducted using both (i) a finite element model of the full bridge under various CL-625 truck loading configurations and (ii) the CHBDC load distribution method, and both agreed well. Scaling analysis of the girder load share was then conducted to account for shortening it to 16 m to fit in the laboratory, resulting in two-115 kN ROLLS design loads, 1.2 m apart. Multiple passes were conducted at various loads of 40%–100% of the design load, at speeds of 1–5 m/s to examine the machine and girder behaviours. It was found that the applied load fluctuates by less than 10% of full capacity and a 0.13 s/cycle time lag occurs. The measured girder deflection and elastic strains were 11%–20% lower than predicted theoretically. With the two half-axles assembly spaced at 1.2 m, the apparatus has the ability to complete three million cycles in approximately 4.5 months if ran continuously at 5 m/s. [ABSTRACT FROM AUTHOR]

This paper presents an experimental program to justify the barrier design at the barrier-deck junction when compared to the factored applied transverse vehicular loading specified in the Canadian Highway Bridge Design Code (CHBDC). Compared to the dimensioning and the glass fibre reinforced polymer (GFRP) bar detailing of a recently crash-tested GFRP-reinforced barrier, the adopted barrier configurations in this paper were similar to those specified by Ministry of Transportation of Québec (MTQ) for TL-5 barrier except that the base of the barrier was 40 mm narrower and the deck slab is of 200 mm thickness, leading to reduction in the GFRP embedment depth into the deck slab. Four full-scale TL-5 barrier specimens were tested to collapse. Correlation between the experimental findings and the factored applied moments from CHBDC equivalent vehicle impact forces resulting from the finite-element modelling of the barrier-deck system was conducted followed by recommendations for use of the proposed design in highway bridges in Québec. [ABSTRACT FROM AUTHOR]

Greater opportunity now exists compared to 35 years ago for civil engineers to apply river ice knowledge to practical problems of planning, designing, and operating hydro-power facilities, water intakes, bridges, and other infrastructure along ice-covered rivers. This is due to major advancements made during this period in understanding the physical processes of river ice formation, growth and breakup, in developing instrumentation for acquisition of information on winter environments, and in developing numerical modelling tools. An increasing number of journal articles, as well as papers presented at the river ice workshops of the CGU Committee on River Ice Processes and the Environment (CRIPE) and the ice symposia of the International Association for Hydro-Environment Engineering and Research (IAHR) attest to the advancement in river ice science and engineering knowledge that has occurred during the past 35 years. This paper reviews the developments in river ice science and engineering from a Canadian perspective and briefly discusses future directions. [ABSTRACT FROM AUTHOR]

Fusing collected inspection data provides comprehensive and relatively more accurate diagnostics of defects and accordingly more accurate condition assessment of structures. This paper presents a new two-tier method that utilized data fusion methods for condition assessment of reinforced concrete bridge decks. The method utilizes pixel and feature levels fusion of data collected from multiple nondestructive evaluation (NDE) methods such as ground penetrating radar, impact echo, half-cell potential, and electrical resistivity. Data and measurements of NDE methods are extracted from the Iowa Highway research board project 2011 report for three case studies. It is observed from the three cases that each level of data fusion has its unique advantage. The power of pixel level fusion lies in its ability to provide an overview of bridge deck deterioration in one map as it appears in the fused image. On the other hand, feature fusion works better when only specific types of defects such as corrosion, delamination, and deterioration captured from inspection carried out by each of technologies referred to above. The proposed method is tested against filed inspection methods and core sample results described in the three case studies. The main findings of this research recommend utilizing data fusion in two levels as a new method to facilitate and enhance the confidence and capabilities of inspectors in interpretation of the NDE test results. [ABSTRACT FROM AUTHOR]

Through an experimental study, this paper describes the behavior of single-lap bonded and bolted-bonded connections for configurations with minimum geometric parameters proposed in design references. Two types of multi-material connections are considered: glass fiber reinforced polymer (GFRP)-steel and aluminum-steel. At first, the behavior of bonded connections using methacrylate and epoxy adhesives is evaluated. Then, the contribution of adhesive in bolted connections is investigated. Test results show that on bonded joints, failures mostly occur at the substrate to adhesive interface. Sanding the GFRP plate was found to improve the connection strength. Despite their lower elastic modulus, methacrylate adhesives with larger capacity to undergo plastic deformation provide better strength than other methacrylate and epoxy adhesives. For bolted-bonded joints, the adhesive was found to improve the elastic behavior and the strength of GFRP-steel joints while its effect for aluminum-steel joints was not apparent due to reduced bonded surface and the high strength performance of the bolted plates. [ABSTRACT FROM AUTHOR]

This paper examines two new types of bridges, namely under-deck cable-stayed bridges and combined cable-stayed bridges, for prestressed concrete road bridges with single-spans of medium length. Both bridge types offer many advantages over conventional schemes in several aspects, such as structural efficiency, enhanced construction possibilities, and both economic and aesthetical considerations. They are very slender structural types with a very high structural efficiency, for which the materials used in the deck are reduced to one third of that in conventional bridges without stay cables. In this paper, the most important aspects of the structural behaviour of these bridge types are set out through the description of a careful selection from an extensive collection of bridges designed and analysed by the authors in a previous research project. In addition, a detailed set of design criteria for these bridge types is presented, based on the results of the extensive parametric study undertaken in the aforementioned research project. Cet article étudie deux nouveaux types de ponts, les ponts à haubans sous pont et les ponts à haubans combinés, pour les ponts autoroutiers en béton précontraint à portée unique de longueur moyenne. Les deux types de ponts présentent plusieurs avantages par rapport aux méthodes conventionnelles, soit l’efficacité de la structure, de meilleures possibilités de construction et des aspects économiques et esthétiques. Ce sont des types de structures très effilées avec une efficacité de structure très élevée, dans lesquels les matériaux utilisés dans le tablier sont réduits au tiers de ceux des ponts conventionnels sans haubans. Dans cet article, les plus importants aspects du comportement structural de ces types de ponts sont énoncés dans la description d’une sélection soignée d’une série complète de ponts conçus et analysés par les auteurs dans le cadre d’un projet de recherche antérieur. De plus, un ensemble détaillé des critères de conception de ces types de ponts est présenté; il est basé sur les résultats d’une vaste étude paramétrique entreprise lors du projet de recherche mentionné précédemment. [ABSTRACT FROM AUTHOR]

As part of ongoing efforts to accelerate bridge construction in Ontario, the Ministry of Transportation of Ontario (MTO) has turned increasingly to prefabricated bridge technology as a bridge construction method when conditions allow. One of the prefabricated deck systems commonly used by MTO involves installing precast full-depth deck panels with pre-formed shear pockets on top of the naked steel girders, which are then made composite with the girders through shear studs installed inside the shear pockets. Construction of the deck slab is completed by filling the shear pockets with in situ concrete. Recent prefabricated bridge projects have shown an increasing tendency to concentrate the shear studs into clusters of closely-spaced studs in shear pockets that are spaced at relatively large distances apart. Concerns have been raised about the effectiveness of the resulting composite action between the precast panels and the supporting girders. As a result, MTO's Bridge Office recently carried out a comprehensive experimental research study to investigate the issue by using reduced scale models of single composite beam systems as well as shear push-out specimens. This paper describes the laboratory research project and the tests that were carried out and discusses the results obtained. Comparisons with theoretical results are made to assess the composite action that is developed. Experimental test results indicate that closely-spaced studs in the shear pockets in the precast deck panels provide adequate composite action in composite bridge girder design. [ABSTRACT FROM AUTHOR]

Recent research efforts have focused on the development of performance based seismic design methodologies for structures. However, the seismic design rules prescribed in the current Canadian Highway Bridge Design Code (CHBDC) is based largely on force based design principles. Although a set of performance requirements (performance objectives) for different return period earthquake events have been specified, there is no explicit requirement in the CHBDC to check the attainment of such performance objectives for the designed bridges. Also, no engineering parameters have been assigned to the specified performance objectives. This paper correlates seismic performance objectives (both qualitative and quantitative) with engineering parameters, based on the data collected from published experimental investigations and field investigation reports of recent earthquakes. A simple method has been developed and validated with experimental results for assessing the performance of bridges designed according to CHBDC. It has been found that the design rules prescribed in CHBDC do not guarantee that specified multiple seismic performance objectives can be achieved. An implicit seismic design rule in the form of performance response modification factor has been outlined for the performance based seismic design of bridges. [ABSTRACT FROM AUTHOR]

Corrosion of the reinforcing steel is a primary deterioration mechanism for reinforced concrete bridges. The spatial distribution of such spalling, relative to bar splices and laps, has not been considered in previous studies and may have a significant influence on structural capacity. In this paper, a modified area concept for considering this spalling is proposed. A methodology has been developed that employs this concept for the practical evaluation of existing bridges. It uses graphical spalling surveys, reinforcement layout information, and existing information regarding material and geometric properties as inputs for the flexural and shear analysis of deteriorated bridge girders. This methodology is easily adapted for full bridge analysis and to consider the effects of bar section loss and bond deterioration. A case study bridge is evaluated to show that this methodology offers a viable tool for the rapid assessment of spalled bridge girders to facilitate the prioritization of rehabilitation projects. [ABSTRACT FROM AUTHOR]

This paper investigates the use of a pre-existing network of resistive strain gauges located on the girders of a single bridge span to determine the classification and estimate the weight of vehicles traveling over that span. Vehicle events on the bridge are identified automatically by a measurement filtering algorithm. Manual classification labels are then applied to a subset of these events to investigate the strain signal features that distinguish various vehicle classes. Trends in these features over time are investigated, and an estimate of vehicle weight is obtained from these features without the need for detailed knowledge of the structure's composition. Additionally, a number of neural network configurations are tested on the problem of determining vehicle class from these features. Results are tested on data from both the summer and winter seasons. Finally, estimates of vehicle weight are improved by using the classification network to filter input events. Cet article examine l'utilisation d'un réseau existant de jauges de déformation résistives situées sur les poutres maîtresses d'une travée de pont afin de déterminer le classement et estimer le poids des véhicules voyageant sur cette travée. La circulation des véhicules sur le pont est identifiée automatiquement par un algorithme de filtrage des mesures. Des étiquettes manuelles de classement sont ensuite appliquées à un sous-ensemble de la circulation afin d'examiner les caractéristiques des signaux de contrainte qui distinguent les diverses classes de véhicules. Les tendances de ces caractéristiques dans le temps sont étudiées; une estimation du poids des véhicules est obtenue à partir de ces caractéristiques sans demander une connaissance détaillée de la composition structurale. De plus, un certain nombre de configuration de réseaux neuronaux ont été mis à l'épreuve afin d'essayer de déterminer la classe de véhicule à partir de ces caractéristiques. Les résultats sont examinés par rapport aux données estivales et hivernales. Pour compléter, les estimations des poids de véhicules sont améliorées en utilisant le réseau de classification afin de filtrer les événements saisis. [ABSTRACT FROM AUTHOR]

Compression members in steel bridges designed before 1960 may be deficient according to current design code requirements and so require strengthening. This paper explores the response of steel wide-flange columns reinforced with new steel flange cover plates, accounting for: residual and locked-in dead-load stresses; different yield strengths of the original W shape and the new cover plates; initial out-of-straightness; and load eccentricity at the member ends. A refined numerical analysis model is formulated and validated that computes the compressive resistance from principles of equilibrium, compatibility, and force-deformation relationships. Parametric studies conducted indicate that the capacity of the reinforced column is relatively insensitive to the magnitude of the locked-in dead-load stress in the original member, and that the strong axis capacity is insensitive to the magnitude of the residual stresses in the original member. A preliminary approach for designing strengthening for these members is presented and illustrated with an example calculation. Les éléments en compression des ponts en acier conçus avant 1960 peuvent être inadéquats selon les exigences du code de conception actuel; ils auraient donc besoin d’être renforcés. Cet article examine la réponse des colonnes en poutres d’acier à brides, renforcées de nouvelles plaques d’acier de recouvrement, tenant compte des contraintes statiques résiduelles, des contraintes permanentes, des différentes limites d’élasticité du profilé original en forme de W et les nouvelles plaques de recouvrement des brides, la non-linéarité initiale et l’excentricité des charges aux extrémités des éléments. Un modèle d’analyse numérique perfectionné est préparé et validé; il calcule la résistance à la compression à partir des principes d’équilibre, de compatibilité et de relations contrainte-déformation. Des études paramétriques effectuées indiquent que la capacité de la colonne renforcée est relativement insensible à l’amplitude de la charge statique permanente dans l’élément original, et que la capacité de l’axe majeur est insensible à l’amplitude de la charge résiduelle dans l’élément original. Une approche préliminaire à la conception du renforcement pour ces éléments est présentée et illustrée par un exemple de calcul. [ABSTRACT FROM AUTHOR]

The ISIS Canada Networks of Centres of Excellence (NCE) program has focused on two main themes to improve civil engineering infrastructure, namely innovative construction technologies, and structural health monitoring (SHM). The former began with the construction of the first field application of the innovative steel-free concrete bridge deck slab technology at the Salmon River bridge, Nova Scotia, in 1995. Although this bridge has continued to function safely under heavy traffic loads, it has developed characteristic longitudinal cracking of the concrete between adjacent girders due to fatigue. This paper describes the recent research to develop an SHM model for monitoring the impact and stability of this cracking. Theoretical and experimental models were used to examine the change in response as cracking develops. A global load distribution matrix was proposed, and the variation in load distribution values with cracking was used to develop a cracking index that can be employed in monitoring the field structure. [ABSTRACT FROM AUTHOR]

This paper presents a synthesis of the design provisions of the second edition of the Canadian Highway Bridge Design Code (CHBDC) for fibre-reinforced structures. New design provisions for applications not covered by the first edition of the CHBDC and the rationale for those that remain unchanged from the first edition are given. Among the new design provisions are those for glass-fibre-reinforced polymer as both primary reinforcement and tendons in concrete; and for the rehabilitation of concrete and timber structures with externally bonded fibre-reinforced-polymer (FRP) systems or near-surface-mounted reinforcement. The provisions for fibre-reinforced concrete deck slabs in the first edition have been reorganized in the second edition to explicitly include deck slabs of both cast-in-place and precast construction and are now referred to as externally restrained deck slabs, whereas deck slabs containing internal FRP reinforcement are referred to as internally restrained deck slabs. Resistance factors in the second edition have been recast from those in the first edition and depend on the condition of use, with a further distinction made between factory- and field-produced FRP. In the second edition, the deformability requirements for FRP-reinforced and FRP-prestressed concrete beams and slabs of the first edition have been split into three subclauses covering the design for deformability, minimum flexural resistance, and crack-control reinforcement. The effect of sustained loads on the strength of FRPs is accounted for in the second edition by limits on stresses in FRP at the serviceability limit state. [ABSTRACT FROM AUTHOR]

The Canadian Highway Bridge Design Code (CHBDC) provides two alternative methods for evaluating the strength of existing bridges. The load and resistance factor method provides a general approach and covers the most extreme load situations that can occur in a general bridge population. The mean load method considers the uncertainties of loads acting on a specific bridge, the method of analysis, and resistance of the structure involved, and thus can provide a more accurate evaluation of individual bridges. Since traffic load represents a major portion of bridge loads, a better evaluation of specific bridges is obtained by using the statistical parameters of traffic loads observed on the structure. However, the overall accuracy depends heavily on capturing the most critical loading conditions during the survey periods. The mean load method is particularly valuable where actual traffic loads are expected to be significantly lower than those used in code calibration and when the potential economic benefits arising from a more realistic evaluation outweigh the extra costs of live load data collection and analysis. This paper demonstrates that the mean load method using site-specific traffic loading information can lead to a significantly higher live load-carrying capacity of a bridge. [ABSTRACT FROM AUTHOR]

This paper presents an analytical approach for predicting the length limits of integral bridges built on cohesive soils based on the flexural strength of the abutments and the low cycle fatigue performance of the steel H-piles at the abutments under cyclic thermal loading. First, H-piles that can accommodate large inelastic deformations are determined considering their local buckling instability. Then, a damage model is used to determine the maximum cyclic deformations that such piles can sustain. Next, nonlinear static pushover analyses of typical integral bridges subjected to cyclic thermal variations are conducted to study the effect of various geometric, structural, and geotechnical parameters on their performance. Equations are derived by using the analyses results to determine the maximum length limits of integral bridges built on cohesive soils. It is found that the maximum length limits of integral bridges is affected by the stiffness of the deck, height of the abutment, properties, and orientation of the piles as well as stiffness of the cohesive soils. [ABSTRACT FROM AUTHOR]

The type and arrangement of bearings for a bridge superstructure are important considerations in bridge design. For a curved continuous spread-box girder bridge, the support conditions for the bridge superstructure may significantly influence the distribution factors for maximum stresses, reactions, and shear forces as well as the bridge natural frequencies and mode shapes. Current design practices in North America recommend very few guidelines for bearing arrangements and types. This paper describes an extensive study carried out using an experimentally calibrated finite element model, in which curved continuous prototype bridges were analyzed to determine their structural response. Six different types and arrangements of support bearings were studied to determine their effect on the maximum stress and reaction distributions as well as on the natural frequencies of such bridges. The results were used to suggest the most favourable bearing arrangement and type.Key words: bridge bearings, composite, continuous, curved bridges, design, distribution factors, finite element, spread-box.Le type et l'arrangement de supports pour une structure de pont sont des considérations importantes pour la conception de ponts. Pour un pont poutre-caisson continu et courbé, les conditions de support de la structure peuvent influencer significativement les facteurs de distribution des contraintes maximales, des réactions et des forces de cisaillement, de même qu'influencer les fréquences naturelles et les formes des modes du pont. Les pratiques de conception en vigueur en Amérique du Nord donnent peu de directives concernant les arrangements et types de supports. Cet article présente une étude détaillée entreprise à l'aide d'un modèle par éléments finis calibré expérimentalement, dans laquelle des prototypes de ponts continus et courbés sont analysés afin de déterminer leur réponse structurale. Six différents types et arrangements de paliers de support sont étudiés afin de déterminer leur effet sur la contrainte maximale et les distributions des réactions, de même que sur les fréquences naturelles de tels ponts. Basé sur les résultats obtenus, l'arrangement et le type de support les plus favorables sont suggérés.Mots clés : supports de ponts, composite, continu, ponts courbés, conception, facteurs de distribution, élément fini, caisson.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

During the past decade, composite steel-free deck bridges came to reality in Canada through the construction of five bridges. The new structural system enables the construction of a concrete deck that is totally devoid of all internal steel reinforcement. Traditionally, reinforced concrete bridge decks are designed to sustain loads in flexure. The steel-free deck bridge system develops internal compressive forces "internal arching," which leads to failure by punching shear at substantially higher loads than the flexural design load. The fibre-reinforced concrete deck is usually attached to the steel girders through flexible shear connectors. These steel girders are transversely tied together by steel straps and cross frames. In this paper, the concept of the new bridge system is briefly discussed. The generations of the deck slabs are introduced. Brief outlines of the bridges built to date with this new technology are presented. A three-dimensional finite element model is then proposed to study the behaviour of the main structural component of the new system. The model is verified against previous experimental results and is used to perform a parametric study on some aspects which are thought to significantly affect the behaviour of the new steel-free deck bridge system.Key words: bridges, composite girders, finite element method, steel-free deck, steel straps.Durant la dernière décennie, les ponts à tablier composé sans acier sont devenus réalité au Canada grâce à la construction de cinq ponts. Ce nouveau système structural permet la construction d'un tablier en béton qui est complètement dépourvu de tout renforcement interne en acier. Traditionnellement, les tabliers de pont en béton armé sont conçus afin de supporter des charges en flexion. Le système de tablier de pont sans acier développe des forces internes en compression « cintrage interne » et résulte en une rupture par poinçonnement en cisaillement pour une charge substantiellement plus grande que les charges en flexion de conception. Le tablier en béton renforcé de fibres est habituellement attaché aux poutres d'acier à l'aide de connexions de cisaillement flexibles. Ces poutres d'acier sont attachées ensemble transversalement à l'aide de liens d'acier et de contreventements. Dans cet article, le concept de ce nouveau système est brièvement discuté. Les générations des tabliers en dalles sont introduites. Un bref aperçu des ponts construits à ce jour avec cette nouvelle technologie est présenté. Un modèle par éléments finis tirdimensionnel est par la suite proposé afin d'étudier le comportement des composants structurels principaux du nouveau système. Le modèle est confronté aux résultats expérimentaux obtenus par d'autres dans le passé. Ensuite, il est utilisé afin de performer une étude paramétrique sur quelques aspects qui sont suspectés d'affecter de façon significative le comportement de ce nouveau système de tablier de pont sans acier.Mots clés : ponts, poutres composées, méthode par éléments finis, tablier sans acier, liens d'acier.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The continuing trend towards the design of more slender, lighter, and livelier footbridges has created new challenges that are not properly addressed in a number of widely used codes of practice in Europe and Canada. Recent research into vibration serviceability of slender structures under human-induced dynamic loading suggests that improvements to the existing footbridge design guidelines are possible in the area of modelling human-induced excitation in the vertical direction. This paper evaluates the performance of currently used codes of practice regarding vibration serviceability of footbridges under human-induced loads due to walking. The evaluation is supported by experimental evidence from tests carried out by the authors on potentially lively footbridges. A description of recent research advances is included, together with a comparative analysis of the approaches of some pertinent guidelines used internationally to tackle this design problem. In addition, suggestions are made for re-addressing the problem of vibration serviceability of footbridges by focusing attention on a more realistic definition of vertical pedestrian loading and the corresponding frequency ranges of interest. It was found that the codes are either conservative or lack appropriate safety margins, depending on the frequency range excited by moving pedestrians. This is principally due to the lack of proper consideration for the frequency content of the pedestrian load, which would take into account developments since the 1970s when the scientific data used in the majority of the current codes of practice were produced.Key words: vibration, serviceability, walking, footbridges, design, codes, dynamic loading factor, evaluation.La tendance continue vers la conception de passerelles plus minces, légères et vivantes a créé de nouveaux défis qui ne sont pas adéquatement considérés dans plusieurs codes de pratique largement utilisés en Europe et au Canada. Une récente étude, concernant l'état de service à l'égard des vibrations des structures minces sous l'influence de charges dynamiques produites par les humains, suggère que des améliorations aux présents guides de conception des passerelles sont possibles dans le domaine de la modélisation des excitations produites par les humains dans la direction verticale. Cet article évalue la performance des codes de pratique utilisés présentement en ce qui concerne l'état de service à l'égard des vibrations des passerelles sous l'influence de charges dynamiques produites par le trafic piétonnier. L'évaluation est supportée par des évidences expérimentales provenant de tests performés par les auteurs sur des passerelles potentiellement vivantes. Une description des nouveaux avancements dans la recherche est inclue avec une étude comparative des approches considérées par certains guides appropriés utilisés à travers le monde afin de résoudre ce problème de conception. En plus, des suggestions ont été faites afin de reprendre le problème de l'état de service des passerelles en portant une attention spéciale sur la définition plus réaliste de la charge verticale due aux piétons et des intervalles de fréquences correspondants. Il a été démontré que les codes sont soit trop conservateurs ou soit n'ont pas une marge de sûreté appropriée, dépendant des intervalles de fréquences excités par les piétons. Ceci est dû principalement au manque de considération du contenu fréquentiel de la charge piétonnière qui devrait considérer les développements depuis les années 1970, période dans laquelle les données scientifiques utilisées dans la majorité des codes de pratique a été produites.Mots clés : vibration, état de service, marche, passerelle, conception, codes, facteur de charge dynamique, évaluation.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]