Journal of Bridge Engineering

This state-of-the-art paper presents the results of a comprehensive literature review of the cause of transverse deck cracking. It includes compilation of experimental and analytical research results as well as survey studies on the effects of different factors on concrete deck cracking. Consistent with the past work on the subject, causes of transverse deck cracking are classified under three categories, namely: (1) material and mix design, (2) construction practices and ambient condition factors, and (3) structural design factors. The literature review revealed that the first two items have been studied extensively over the past several decades, while literature is limited on the effect of structural design factors on deck cracking. This paper evaluates the existing work in depth and presents recommendations on mix design and construction procedures to reduce the potential for transverse deck cracking. Furthermore, areas for additional research are identified.

 Early transverse cracking is one of the dominant forms of bridge deck defects experienced by a large number of transportation agencies. These cracks often initiate soon after the bridge deck is constructed, and they are caused by restrained shrinkage of concrete. Transverse cracks increase the maintenance cost of a bridge structure and reduce its life span. Most of the past efforts addressing transverse bridge deck cracking have focused on changes over the years in concrete material properties and construction practices. However, recent studies have shown the importance of design factors on transverse bridge deck cracking. This paper presents results of a comprehensive finite-element (FE) study of deck and girder bridge systems to understand and evaluate crack patterns, stress histories, as well as the relative effect of different design factors such as structural stiffness on transverse deck cracking. The results of this study demonstrate the development of transverse deck cracking and emphasize the importance of these design factors. They also recommend preventive measures that can be adopted during the design stage in order to minimize the probability of transverse deck cracking.

The objective of this research is to investigate the seismic performance of as-built, retrofitted, and repaired hollow bridge columns with insufficient shear strength. Two as-built full-scale columns were first tested and repaired using carbon-fiber-reinforced polymer composites (CFRP) jackets and dog-bone-shaped bars and then retested. Another two columns having the same reinforcement as the as-built columns were retrofitted with CFRP jackets. In addition to the tests, the repairability of the failed hollow columns was investigated by analytical evaluation. The test results and analysis of the retrofitted columns showed that CFRP composites can effectively strengthen shear-critical hollow bridge columns and can successfully transform the failure mode from shear to flexure. The test results of the repaired circular columns show that dog-bone-shaped bars successfully repaired the flexural damage caused by the fractured longitudinal bars.

Traditional bridge evaluation techniques are based on design-based deterministic equations that use limited site-specific data. They do not necessarily conform to a quantifiable standard of safety and are often quite conservative. The newly emerging load and resistance factor rating (LRFR) method addresses some of these shortcomings and allows bridge rating in a manner consistent with load and resistance factor design (LRFD) but is not based on site-specific information. This paper presents a probability-based methodology for load-rating bridges by using site-specific in-service structural response data in an LRFR format. The use of a site-specific structural response allows the elimination of a substantial portion of modeling uncertainty in live load characterization (involving dynamic impact and girder distribution), which leads to more accurate bridge ratings. Rating at two different limit states, yield and plastic collapse, is proposed for specified service lives and target reliabilities. We consider a conditional Poisson occurrence of identically distributed and statistically independent (i.i.d.) loads, uncertainties in field measurement, modeling uncertainties, and Bayesian updating of the empirical distribution function to obtain an extreme-value distribution of the time-dependent maximum live load. An illustrative example uses in-service peak-strain data from ambient traffic collected on a high-volume bridge. Serial independence of the collected peak strains and of the counting process, as well as the asymptotic behavior of the extreme peak-strain values, are investigated. A set of in-service load and resistance factor rating (ISLRFR) equations optimized for a suite of bridges is developed. Results from the proposed methodology are compared with ratings derived from more traditional methods.

The simplified equal distribution factor (EDF) method for live load shear presented in this study originates from Henry’s method, a method that has been used in Tennessee for nearly forty years. Henry’s method allows for equal distribution of live load effects in all beams. This study focused on a careful examination and modification of Henry’s method by comparing shear distribution factors obtained from Henry’s method with those from finite element analysis and other code-specified methods for actual bridges. Twenty-four Tennessee bridges with six different types of superstructures were used in the study. The effects of structural parameters on the shear distribution factors were also studied. Modification factors to Henry’s method were proposed based on the comparison study. The proposed modification factors include structure type factors that are applied to different types of superstructures and a skew correction factor that is used to account for the effects of skew angle for skewed bridges. With proper modifications, the simplified EDF method can produce very reasonable and reliable distribution factors for live load shear.

Bearings are used to support loads and accommodate movements in bridges. Cotton duck bearing pads (CDP) offer a versatile and economical solution for bearing design. The CDPs have closely spaced layers of elastomer and fabric which result in large compressive strength and strain capacities. However, the engineering response of CDP has not been well understood and CDP design provisions are incomplete because of this limited knowledge. To better establish the engineering response and develop improved design provisions, an extensive experimental research study was conducted. The experimental program modeled loads and deformations induced on a bridge bearing and included both static and dynamic loading regimes in compression, shear, and rotation. The primary study parameters included pad geometry, pad manufacturer, and stress and strain levels. The results indicate that CDPs have significant compressive stress and deformation capacities. Using the experimental results, design limits to control pad damage and quality assurance provisions are proposed to ensure adequate service during the lifetime of the bridge. Delamination of the top pad layers occurs after many cycles of repeated load or deformation and limits on the maximum stress, stress range, and uplift are proposed to limit this type of damage. Diagonal fracture occurs when a CDP is subjected to large strains. Strict maximum strain limits are proposed to prevent this failure mode. Finally, quality control provisions are proposed to ensure adequate engineering performance of the pads.

Deflection of a bridge span under designed loads is an important parameter for bridge safety evaluation. However, it is inconvenient to obtain the bridge deflections directly. For bridges over rivers, railways, or highways, a direct measurement method is impractical. A promising bridge deflection measurement method (inclinometer method) is presented in this paper. It offers a simple, practical and inexpensive method of measuring static and dynamic deflections of bridge spans under loads, even for bridge spans that traverse great heights. Hundreds of experiments and practical tests on simple and continuous bridges, utilizing dynamic and static loads, under various vehicle speeds, show that the method has very high precision, which provides an authentic basis for new-built bridge acceptance and old bridge safety evaluation. The method does not need fixed observation positions as other deflection measurement methods because the inclinometers are installed on the bridge directly, which increases measurement efficiency greatly. These features indicate that as a potential method of measuring bridge deflection, inclinometers have significant engineering application value and a promising future.

The way in which a new road bridge made of steel corrugated plates Super Cor type was tested during the three stages of its construction is described and the test results are presented. Backfill in construction Stage I and two ballasting vehicles in Stages II and III constituted the loads. The box bridge spans the Bystrzyca Dusznicka River in Polanica Zdroj, Poland. The span’s effective length is $12.27\mathrm{m}$ and its vertical inside diameter is $3.85\mathrm{m}$ . The steel span is founded on two reinforced concrete strip foundations. The average values of the displacements and strains (normal stresses) measured in selected points and on selected elements of the steel shell structure were much smaller than the ones computed for the same load. The conclusions drawn from this research can be helpful in determining the interaction between the steel shell and the backfill. Since this type of steel–soil structure is increasingly used in Poland and in the world, the conclusions can be generalized to a whole class of similar bridge designs.

This paper presents the results and conclusions of the research conducted on a backfilled shell structure made of Super Cor SC-56B corrugated steel plates of a road bridge located in Gimån, Sweden. The conclusions drawn from the tests can be helpful mostly for the assessment of the behavior of this type of steel–soil bridge structure under the load of backfilling. In consideration of an even more frequent application of this type of structure for small and middle-sized road and rail bridges, conclusions from the conducted research can be generalized to the whole class of such structural solutions.

The way in which a new road bridge made from Super Cor steel plates was tested is described and the test results for three static load schemes in which one ballasting vehicle (a Scania truck) was used as the load are presented. The tested bridge has a box structure and it is located on the Gimån River in Gimån, Sweden on the Bräcke-Holm road. The bridge has an effective span of $12.315\mathrm{m}$ and a clear height of $3.555\mathrm{m}$ . The span’s steel shell is founded on two reinforced concrete continuous footings. The average measured displacements and strains (normal stresses) in selected points and elements of the steel shell structure were found to be much smaller than the ones calculated for the same load. The conclusions drawn from this research can be useful for assessing the performance of such steel shells and their interaction with the surrounding backfill. Since such steel–soil designs are used more and more often for small and medium-sized bridges on road and railway lines in Poland and in the world, the conclusions from the static load tests can be generalized to a whole class of similar bridge designs.

United States highway bridge design has advanced into the era of risk-based practice, milestoned by the American Association of State Highway and Transportation Officials Load and Resistance Factor Design Bridge Design Specifications. On the other hand, national and state design codes cannot specifically account for localized risk for each bridge site, which may have significantly different loading conditions from the national average. This issue is focused on here, as related to the adequacy of current bridge design loads for sites in the state of Michigan. The structural reliability indices are calculated for a randomly selected sample of new bridges from the Michigan inventory, including four major girder bridge types. Weigh-in-motion truck load data collected in Michigan are used to statistically characterize the truck load effect in the bridges’ primary members for moment and shear at critical cross sections. The reliability indices are found to vary significantly among the bridge sites and types investigated. Many of them indicate inadequate design load for the Detroit area.