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Evaluating the technical conditions and performance for historic bridges is essential to ensure their structural safety and determine their need for strengthening. This study investigates the first railway steel bridge built in China in 1894, which is listed as a national preservation unit and industrial heritage site. The bridge was not only exposed to years of weather change but also suffered a geological disaster in 1976. In addition, the surroundings have changed, including the construction of new railway lines and scenic areas. Thus, it is imperative to evaluate its technical conditions and performance, particularly its material properties. To this end, evaluation procedures were formulated. First, the material composition, properties, and grades of steel were determined by microstructural analysis: the grade of nonmetallic inclusions in steel was determined by metallographic analysis; the corrosion rate of steel was obtained by electrochemical analysis; and the crystal type, size, element product of the corrosion layer, as well as the fracture type of the steel, were analyzed by phase composition and elemental analysis. Next, the static performance indices of the steel were obtained by mechanical property tests: the hardness value of the steel was obtained from hardness test; the yield and tensile strengths of the steel were obtained from tensile tests; and the fatigue properties of the steel were analyzed through fatigue tests. The S-N curve of the steel was determined by fitting the tested data. This study provides a reference for the evaluation of the technical conditions and performance of historic bridges. [ABSTRACT FROM AUTHOR]

What is the current state-of-the-art for image restoration and enhancement applied to degraded images acquired under less than ideal circumstances? Can the application of such algorithms as a pre-processing step improve image interpretability for manual analysis or automatic visual recognition to classify scene content? While there have been important advances in the area of computational photography to restore or enhance the visual quality of an image, the capabilities of such techniques have not always translated in a useful way to visual recognition tasks. Consequently, there is a pressing need for the development of algorithms that are designed for the joint problem of improving visual appearance and recognition, which will be an enabling factor for the deployment of visual recognition tools in many real-world scenarios. To address this, we introduce the UG $^2$ 2 dataset as a large-scale benchmark composed of video imagery captured under challenging conditions, and two enhancement tasks designed to test algorithmic impact on visual quality and automatic object recognition. Furthermore, we propose a set of metrics to evaluate the joint improvement of such tasks as well as individual algorithmic advances, including a novel psychophysics-based evaluation regime for human assessment and a realistic set of quantitative measures for object recognition performance. We introduce six new algorithms for image restoration or enhancement, which were created as part of the IARPA sponsored UG $^2$ 2 Challenge workshop held at CVPR 2018. Under the proposed evaluation regime, we present an in-depth analysis of these algorithms and a host of deep learning-based and classic baseline approaches. From the observed results, it is evident that we are in the early days of building a bridge between computational photography and visual recognition, leaving many opportunities for innovation in this area. [ABSTRACT FROM AUTHOR]

In contrast to the Swiss load model used for new bridge structures (SIA 261), which has roots in a Europe‐wide weigh‐in‐motion (WIM) study and considers the full design life of new structures, the model for existing structures (SIA 269) from 2005 is derived from load effects produced by traffic measured by country‐specific WIM observations and considers a reduced return period. With growing concerns regarding the scarcity of resources, efforts should be made to ensure safety by increasing the knowledge of loads and load‐carrying mechanisms, rather than through overdesign. This paper presents the methodology employed to use WIM data for generating maximum expected load effects on bridges and thus give engineers a tool with which bridge load effects can be accurately derived from real traffic. A re‐evaluation using the methodology outlined here began this year. It is planned to use the results of this for the next revision of the Swiss National Annexes to the Eurocodes and SIA 269. [ABSTRACT FROM AUTHOR]

Prestressed concrete continuous beam-arch composite bridge with concrete-filled steel tube is a new type of bridge developed in recent years. It has the characteristics of strong spanning ability and large in-plane stiffness, but the lateral stiffness of the arch ribs for this type of bridge is relatively weak. In order to effectively improve the construction quality and structure stability, and optimize the mechanical properties, and in addition of realize the design of large span continuous beam-arch composite bridge, a comprehensive safety assessment of the Liuxi River bridge during construction and serving stages located in China was conducted in this paper. The results show that the bridge had favorable safety margin during the construction and severing stages. The outcomes of this study can provide technical support for the safety and smooth implementation of the bridge's safeguard, which has important theoretical significance and engineering application value. [ABSTRACT FROM AUTHOR]

In the recent update of AS 5100 (2017 + Amdt. 1, 2018), the Modified Compression Field Theory (MCFT) was introduced for shear design of members. Part 7 of the code, which deals with the assessment of existing structures, directs engineers to use the MCFT provisions of Part 5 (for design) in assessing the shear capacity of an existing member. The MCFT provisions in Part 5 are intended for shear design, rather than shear capacity assessment. Without modification, false shear capacity assessments can result from their use. This note discusses the background to the design rules and explains how capacity assessment should differ. It shows how, through iteration, the design rules can be adopted to give capacity assessments for existing sections. It concludes by showing the errors that can arise for a range of sections, typical of bridge assessments, from the incorrect application of the shear design rules to an assessment problem. Recommendations are given to remove this ambiguity in future editions of AS 5100.7. [ABSTRACT FROM AUTHOR]

• The effectiveness of various strengthening techniques for timber bridges is discussed. • Suitable strengthening methods are identified in terms of girder deflections, reliability, efficiency, and live load distribution. • Parametric investigations are conducted to elucidate the implications of variable geometric configurations and live load intensities. This paper presents the behavior of a timber bridge strengthened with lag bolts, carbon fiber reinforced polymer (CFRP) sheets, and hollow structural sections (HSS). The 83-old bridge is composed of three spans, supported by 14 Douglas Fir girders, and is tested employing truck loadings of 120 kN and 267 kN. Three-dimensional finite element models are formulated to study the flexural response of the bridge with and without the retrofit options. The magnitude of the truck load dominates the degree of dispersion in girder deflections and alters the shape of probability density functions, which are associated with behavioral uncertainty. The effectiveness of strengthening is apparent in terms of reducing the exceedance probability of deflection limits and increasing reliability indices above the design threshold of β = 3.5, stipulated in bridge specifications. Among the three methods, the stiffening efficiency of the HSS option is higher at the system level; however, the use of CFRP is most efficient at the member level. Live load distribution factors are examined and implementable recommendations are provided for practice. Parametric investigations clarify the efficacy of variable HSS sizes and the ramifications of a permit truck weighing 445 kN. [ABSTRACT FROM AUTHOR]

In this paper, an extended Cloud analysis method is developed for seismic fragility assessment of existing highway bridges in the southeast Queensland region. This method extends the original Cloud analysis dataset by performing scaled Cloud analyses. The original and scaled Cloud datasets are then paired to generate seismic fragility curves. The seismic hazard in this region is critically reviewed, and the ground motion records are selected for the time-history analysis based on various record selection criteria. A parametric highway bridge model is developed in the OpenSees analysis software, and a sampling technique is employed to quantify the uncertainties of highway bridges ubiquitous in this region. Technical recommendations are also given for the seismic performance evaluation of highway bridges in such low-to-moderate seismic zones. Finally, a probabilistic fragility study is conducted by performing a total of 8000 time-history analyses and representative bridge fragility curves are generated. It is illustrated that the seismic fragility curves generated by the proposed extended Cloud analysis method are in close agreement with those which are obtained by the rigorous incremental dynamic analysis method. Also, it reveals that more than 50% of highway bridges existing in southeast Queensland will be damaged subject to a peak ground acceleration of 0.14 g. [ABSTRACT FROM AUTHOR]

This paper demonstrates the analysis of the relative deterioration trends of the various types of bridge structural design and/or construction to determine and compare their operational structural performances at the serviceability limit states. The study derives operational data from the entire database of the U.S. National Bridge Inventory and analyzes the actual bridge deck areas rather than bridge counts. Deck areas more realistically reflect the actual sizes of bridge types, enabling a more reliable analysis of deterioration trends and providing more objective structural performances. The study analyzes the trends of the proportional accumulation of deterioration by bridge type, considering criteria based on the concept of structural deficiency and the objective of life-cycle expectancy for uninterrupted service life. The multiple-criteria diagnostic approach integrates the rate and pattern performances, based on deterioration trends, with the condition, durability, and longevity performances to determine and compare the overall equivalent structural performances using prioritized weights. As compared to inventory averages, the results reflect the distinct deterioration trends of bridge types and show a decrease in the equivalent structural performances by 10%. As compared to counts, the equivalent structural performances by areas are lower by 3% for all bridge types and 34-40% for some bridges. Also, the annual maximum average accumulation of structural deficiency of all bridge areas is nearly 20% lower than by counts. The average increase in structural deficiency is 0.42% per year, adding to the already existing 9.38% and constituting an average annual increase of structurally deficient (SD) bridge areas by 4.48%. The analysis also identifies premature accelerated accumulation of deterioration for a particular age group within a bridge type, indicating a critical need to investigate the etiology of the deterioration and improve existing and future bridges. The study provides a comprehensive national network-level comparative experience of the operational structural performances of bridge types by area under actual practices and circumstances to help identify critical deterioration, forecast future structural performance, and promote the sustainability of bridge types. [ABSTRACT FROM AUTHOR]

This paper investigates the evaluation procedure of an AASHTO Type 3 precast-prestressed girder that was extensively damaged by truck impact and then repaired using externally bonded fiber-reinforced polymer (FRP) composites. Results of this study can be applied to bridges having similar vehicle impact incidents. Parameters whose effects were investigated on the evaluation procedure include (1) the effect of horizontal resistance of elastomeric bearing supports, (2) the presence of barrier wall and sidewalk, and (3) live load distribution factors obtained from finite-element analysis (FEA) compared with the simplified method prescribed by other codes. FEA showed that support horizontal resistance has negligible effects on live load distribution factors for shear, Fm, while it has considerable effect on live load distribution factors for moment, Fm. The live load distribution factors Fm and Fv calculated from the simplified method of analysis prescribed by other codes were observed to all be greater than those obtained from FEA, showing that the approach taken by other codes is conservative for the studied bridge. The Fm and Fm of external girders obtained by FEAwere as much as 30 and 40% less than those of other codes. Inclusion of barrier wall and sidewalk in the analysis showed an additional 18% reduction for Fm, with insignificant effect on Fm. The live load capacity factor as the safety indicator in the bridge evaluation was calculated analytically by the load and resistance factor method and the mean load method and then correlated with experimental findings of proof load test on the repaired girder. [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]

• Short-period SHM system is used to assess the bridge safety. • Proposed PARIMA approach used for analyzing the reliability of bridge girders. • PARIMA is significant in detecting structures behaviors. Evaluation and modeling of structures behavior over their service life are crucial parameters for construction safety. This research investigates the use of output-only structural health monitoring (SHM) to evaluate the reliability and safety of highway steel plate girders of WonHyo bridge. Displacement, strain and acceleration measurements were used to assess the bridge behavior under the designed static, semi-static and dynamic truck loads effects. A novel integration method with combined probability, Autoregressive and Integrated Moving Average (ARIMA) identification model was developed to design PARIMA approach, which is introduced and used for analyzing the semi-static and dynamic reliability of the bridge girders. The PARIMA experimentally evaluated structure's reliability and damage based on the output only SHM system. The results showed the effectiveness of PARIMA for detecting structures damages and analyzing structure's reliability in semi-static and dynamic domains. The evaluation of WonHyo bridges showed its performances in time and frequency domains are safe, and the bridge reliability is high. [ABSTRACT FROM AUTHOR]

This paper demonstrates the analysis of the deterioration trends of bridges to evaluate the operational structural performances of the various kinds of bridge construction materials and/or structural designs. The goal of this study is to improve the performance of structural materials used to construct bridges, based on rigorous population-based analysis of the performance of those materials in service. The analysis uses the raw database of the entire National Bridge Inventory in the United States and derives material deterioration aspects at the serviceability limit states. The study develops measures of deterioration to consider the trends in the accumulation of structural deficiency versus service life cycle by material. The approach defines the criteria of rate and pattern performances to analyze the comparative deterioration trends. A multiple-criteria diagnostic approach determines the overall equivalent structural performances integrating the rate and pattern performances with the measures of condition, durability, and longevity. The national network-level operational experience by categorical deterioration trends produces the most comprehensive comparative basis of structural performance of bridge materials. Overall for all bridges, the average increase of structural deficiency is 0.51%/year, adding to the already existing 12.35% and consisting of an average annual increase of structurally deficient bridges by 4.10%. The accumulation of structurally deficient bridges begins only after 10 years for most materials. The rate and pattern performances of almost all of the materials are quite poor. Thus, the equivalent performances integrating the deterioration trends are lower. The results provide a more objective indication and comparison of structural performances under the actual circumstances and help predict future performance. The approach supports the development of improvements necessary to increase the relative performances of distinct bridge materials for more sustainable service. [ABSTRACT FROM AUTHOR]

This paper demonstrates trends in bridge structural deficiency and evaluates the operational structural performance of various types of bridge structural design and/or construction. The study analyzes the database of the National Bridge Inventory and derives data based on actual bridge deck areas, rather than discrete bridge counts. Based on the concept of structural deficiency and the objective of life-cycle expectancy for uninterrupted service life, the multiple-criteria diagnostic analysis determines condition, durability, longevity, and equivalent performance. For some bridge types, the results reflect limited remaining service life before structural deficiency is reached. Average service life is only 56% of life-cycle expectancy. The relatively higher condition performance contrasts with the significantly poor performance of durability and the relatively lower longevity. The equivalent structural performance of some bridge types is low. Overall, the study provides an indication of the current average potential, which serves as a basis for predicting future performance under similar operational conditions. The systems approach supports more objective design, maintenance, and decision-making practices, leading to more effective operation and management and more sustainable infrastructure solutions. [ABSTRACT FROM AUTHOR]

The current practice of detailed seismic risk assessment cannot be easily applied to all the bridges in a large transportation networks due to limited resources. This paper presents a new approach for seismic risk assessment of large bridge inventories in a city or national bridge network based on the framework of probabilistic performance based seismic risk assessment. To account for the influences of local site effects, a procedure to generate site-specific hazard curves that includes seismic hazard microzonation information has been developed for seismic risk assessment of bridge inventories. Simulated ground motions compatible with the site specific seismic hazard are used as input excitations in nonlinear time history analysis of representative bridges for calibration. A normalizing procedure to obtain generalized fragility relationships in terms of structural characteristic parameters of bridge span and size and longitudinal and transverse reinforcement ratios is presented. The seismic risk of bridges in a large inventory can then be easily evaluated using the normalized fragility relationships without the requirement of carrying out detailed nonlinear time history analysis. [ABSTRACT FROM AUTHOR]

This paper evaluates the operational structural performances of the various kinds of bridge construction materials and/or structural designs, considering the deck areas of bridges, rather than their discrete counts. Deck areas represent more objectively the actual constructed capacity in the inventory and the traffic mobility. The study compiles and analyzes the entire bridge inventory in the United States. The analysis uses multiple-criteria diagnostic measures to determine the condition, durability, longevity, and overall equivalent performances. The results provide a comprehensive national network-level comparative basis for bridge material performances at the serviceability limit states. Nearly 99% of all the bridge areas in the inventory have average structural deficiency ages significantly lower than the official life-cycle expectancy. The durability performances indicate that the average service life before structural deficiency is only 42 years. The relatively high condition contrasts with the low durability and longevity performances, reflecting the efforts to improve the condition of bridges. Overall, the average equivalent structural performances of bridge materials by deck areas are quite low, and even lower as compared with performances by bridge counts. [ABSTRACT FROM AUTHOR]

Problem, research strategy, and findings: Public agencies traditionally request bids and award contracts to private firms after infrastructure designs are complete (bid-build). They also increasingly partner with private firms, often by folding capital improvements into a contract to design and build (design-build). The latter involves much more than the mere transfer of design work to the private sector, such as time to completion; the merits or problems of design-build strategies can, thus, be difficult to isolate. This article presents a method for doing so. Together with the development of a theory of contracting, the comparative analysis of two very similar highway overpass projects, one design-build and the other bid-build, demonstrates how so-called transaction cost economics can clarify the details of partnership cost-effectiveness. Takeaway for practice: Transaction cost analysis disaggregates and evaluates the costs of completed projects, accounting for factors typically external to economic analysis. My approach reveals tradeoffs between variables of interest to planners, such as the pace of delivery, public participation, environmental compliance, and the transfer of risk of cost overrun to the private sector. Research support: This research was made possible by a grant from the University of California Transportation Center, shared with Professor David Dowall. [ABSTRACT FROM PUBLISHER]

This article deals with a criterion to extrapolate the frac-ture mechanic test results (CTOD) obtained with medium thickness welded specimens towards thicker joints. The criterion was developed by Italian Institute of Welding (IIS) starting from the available literature correlations between CTOD and J integral and taking into account the results of previous extensive fracture mechanics tests per-formed by IIS on several thicknesses. The criterion was developed within the Stura di Demon-te bridge project (Asti - Cuneo highway) in order to eva-luate the toughness of very thick (140 mm) welds joining the doubling plates of the bridge beams. In particular the extrapolation method allowed to assess the actual joints fracture toughness on the basis of CTOD tests performed on 70 mm thick specimens. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a safety evaluation of steel-plate girder bridges subjected to Military Load Classification (MLC). Three-dimensional finite element models are developed to predict the bridge response, including three different span lengths (L =12m, 24m, and 36m) that represent short- and medium-span bridges. A total of 36 load cases are considered to examine the flexural behavior of the bridges. Evaluation methodologies used here are a critical weight approach and load rating based on the allowable stress rating (ASR), load factor rating (LFR), and load and resistance factor rating (LRFR) methods. The gross weight of the MLC truck is a dominant parameter for the safety of the bridges, rather than longitudinal axle spacing. Load-sharing effects between the girders improve the behavior of the bridge superstructures. Existing empirical formulas developed for nonstandard civilian trucks (e.g., Formula B) exhibit noticeable errors for MLC applications with an average error ranging on the order of 6.7–17.9. The LFR (operating) and the LRFR methods show acceptable rating factors. A safety index of 2.5 is recommended for the evaluation of bridges subjected to MLC trucks. A simplified formula is proposed to promptly assess the critical weight of MLC trucks for short- and medium-span bridges. [Copyright &y& Elsevier]

Structural problems due to corrosion, ageing, durability, aggressive environments, materials defects, lack of ductility and unforeseen behaviour under seismic loads may significantly compromise the resistance and safety of bridges. Scheduled maintenance of bridges becomes important to ensure complete serviceability of the road network. Among existing bridge management systems (BMSs), this work is a contribution to the evaluation criteria of bridge condition by means of visual inspection, prediction of future structural condition and planning of maintenance intervention. After a brief review of some existing BMSs, a simple new procedure for evaluation of bridge condition by means of visual inspection, aimed at general planning of maintenance in a BMS framework, is presented in this paper. This procedure is applied to stock, including about 200 bridges and viaducts, of the Veneto region road network in the north-eastern part of Italy, and is then discussed. [ABSTRACT FROM AUTHOR]

The diagnostic concept of the structural deficiency of bridges is an essential engineering and management consideration with implications of performance. The structural deficiency analysis reflects the constructed system performance at the serviceability limit states. This paper analyzes trends in the structural deficiency of bridge inventory on the basis of material kind. A multiple-criteria diagnostic approach defines measures for condition, durability, and longevity performances and determines the overall equivalent performance. Thus, the structural performance levels reflect the structural reliability and vulnerability indices for bridge serviceability. The application of the approach analyzes the raw database of the entire bridge inventory in the United States. This comprehensive operational experience provides a national network-level comparative basis. The comparison suggests a relative need for improvements in one or more areas, such as design details or maintenance level, to increase the desirability of bridge construction materials. The results support more objective bridge management and decision making on distribution of funds, updating of policies, perfection of practices, and trade-off analyses for design, construction, maintenance, and replacement. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive overview of recent developments in the performance evaluation and flexural response of existing bridges from fundamental concepts to advanced topics. The focus is particularly on the structural evaluation to enhance the quality assessment of constructed bridge superstructures, taking into account a synthesis of the most important contributions to the flexural behavior of existing bridges, such as dynamic responses and lateral load distributions. This state-of-the-art paper provides a critical review of published literature and existing assessment methodologies in conjunction with corresponding analysis techniques, including technical comments on the code provisions. Detailed descriptions of the important parameters influencing flexural responses of existing bridges are discussed, such as the geometric effect, loading configuration, present condition of a bridge, and contribution of secondary structural elements. The review also includes the investigation methodologies, namely, the diagnostic and proof load tests. Finally, the current research needs to further advance the performance evaluation technologies for existing bridge superstructures are recommended. [ABSTRACT FROM AUTHOR]

Methods that identify structural component stiffness degradation by pre- and postevent low amplitude vibration measurements, based on a linear time-invariant (LTI) system model, are conceptually justified by examining the hysteresis loops the structural components experience in such vibrations. Two large-scale shake table experiments, one on a two-column reinforced concrete (RC) bridge bent specimen, and the other on a two-span three-bent RC bridge specimen were performed, in which specimens were subjected to earthquake ground motions with increasing amplitude and progressively damaged. In each of the damaged stages between two strong motions, low amplitude vibrations of the specimens were aroused, and the postevent component stiffness coefficients were identified by optimizing the parameters in a LTI model. The stiffness degradation identified is consistent with the experimental hysteresis, and could be quantitatively related to the capacity residual of the components. [ABSTRACT FROM AUTHOR]

Steel-free deck design is a relatively new approach to bridge deck construction. Several steel-free deck bridges constructed in Canada exhibited satisfactory behaviour immediately after construction. However, the long-term health of many of these structures has not been investigated. Significant cracking has been observed in many of these structures after only a few years in service. Long-term structural health monitoring of these structures is key in determining their long-term performance and future adoption of this new technology. Structural health monitoring data were obtained from the steel-free deck of the Crowchild Trail Bridge during its first seven years in service. Field monitoring included ambient vibration tests, static and dynamic load tests, and deck crack mapping. Despite significant amounts of cracks in the concrete deck and barriers, the overall behaviour of the Crowchild Trail Bridge has remained satisfactory and consistent. Future steel-free deck designs should consider crack control to meet serviceability requirements. [ABSTRACT FROM AUTHOR]

The performance of nine commercially available corrosion-inhibiting systems for use in reinforced concrete structures exposed to corrosive environments was assessed in the field on bridge barrier walls and in accelerated electrochemical cells in the laboratory. The corrosion-inhibiting systems included concrete admixtures, reinforcing steel coatings, and/or concrete surface coatings/sealers. The results of this study are presented in two companion papers, in which the field evaluation and laboratory investigation are reported. The field evaluation consisted of annual corrosion surveys of half-cell potential and corrosion rate, as well as remote monitoring with embedded instrumentation for the measurement of the environmental conditions. After five years of investigation, the system containing an inorganic-based admixture performed better than others in reducing the risk of reinforcement corrosion in the barrier wall. It was also found that the system using epoxy-coated reinforcement showed good early performance during the first year, but after, the risk of corrosion increased relatively faster than in other systems, possibly due to localized pitting corrosion developing in small defects or pores of the epoxy coating. [ABSTRACT FROM AUTHOR]

The article focuses on a study regarding the fatigue assessment of the riveted rail bridges in Great Britain. The researchers have used finite element analyses method to analyze the effect of connection fixity and have classified the fatigue details with special mention to the effect of the simultaneous passage of two trains over the bridge.

The article presents information on a study evaluating the load carrying capacity of masonry arch bridges that are at risk of flooding or have flooded. It reflects that many assessment practices have failed to provide adequate guidance regarding the saturated environmental or flood conditions and its impacts on bridges. Since most of these bridges are constructed with the purpose to span water, the situations during the flood condition should be taken into consideration.

A large number of precast prestressed concrete multi-girder bridges were constructed in Alberta in the early 1960s. Major benefits of this type of construction included the elimination of the cast in place concrete bridge deck and the accelerated pace of construction in erecting the bridge. However, after providing 10 to 20 years of service, some of these bridges started to form longitudinal cracks in the deck directly over the girder joining shear key locations. Once a crack was formed in the shear keys, salt and water would penetrate the wearing surface and weaken the shear key grout. This brought about concerns regarding adequate load sharing among the girders and corrosion of the prestressing tendons within the girders. An extensive survey was undertaken to observe the longitudinal cracking on these bridge decks. The objectives of the field survey were to look for possible trends or relationships between various influencing parameters and the performance of these bridges. Field data were obtained from a visually selected sample survey and a comprehensive bridge record survey based on Alberta Transportation (Government of Alberta) bridge files. The parameters investigated for influence on bridge performance were span length, span width, bridge skew, service age, and traffic volume. Finally, the rehabilitation schemes used on these bridges in the past are described, and the strengths and weaknesses of each rehabilitation strategy are discussed. [ABSTRACT FROM AUTHOR]

This paper demonstrates the analysis of the deterioration trends of the various types of bridge structural design and/or construction in the entire U.S. National Bridge Inventory, to derive and compare operational structural performances. The approach considers the trends of the proportional accumulation of deterioration by bridge types, based on the concept of structural deficiency and the objective of life-cycle expectancy at the serviceability limit states. The analysis determines the rate and pattern of the deterioration trends. The multiple-criteria diagnostic approach integrates the rate and pattern performances with the condition, durability, and longevity performances to determine the overall equivalent structural performances using prioritized weights. This study produces the most comprehensive national network-level comparative basis of the operational structural performances of bridge types under the actual circumstances. The deterioration trend performances of most bridge types are relatively lower. Also, the overall equivalent structural performances of almost all bridge types are lower. The analysis also helps identify critical accumulation of deterioration for bridge types, suggesting focused improvement efforts necessary for existing and future bridges. The most common stringer/multibeam or girder bridges have relatively higher and faster accumulation of deterioration, generating a below average trend and equivalent structural performances. The results help predict future performances and improve effectiveness of bridge types for sustainable service life. [ABSTRACT FROM AUTHOR]