Large numbers of reinforced concrete deck girder bridges that were constructed during the interstate system expansion of the 1950s have developed diagonal cracking in the stems. Though compliant with design codes when constructed, many of these bridges have flexural steel bars that were cut off short of the full length of the girders. When load-rating these structures, the current design specification check of tension reinforcement anchorage often controls the capacity of these bridges. The tensile force demand is controlled by the load-induced moment and shear, the number of stirrups, and the diagonal crack angle; however, little information is available regarding bond stresses developed with larger-diameter bars for full-size specimens in the presence of diagonal cracks. This research used large-size specimens to investigate the influence of diagonal cracks near flexural cutoff locations on the behavior and strength of vintage reinforced concrete girders. Testing indicated that a diagonal crack crossing the development length of cutoff longitudinal bars may not necessarily control specimen failure. Analysis showed that the required tensile demand at a diagonal crack location as predicted by AASHTO LRFD was reasonable. Two analytical methods and a non-linear finite element method were investigated for predicting the failure mode and capacity of the laboratory beams. A procedure was developed to rate existing bridges for flexural anchorage requirements around cutoff locations. Cracking characteristics indicative of flexural reinforcement slippage were defined for bridge inspection.
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Author: Groenier, James Scott | Size: 39.25 MB | Format:PDF | Quality:Original preprint | Publisher: Department of Agriculture | Year: 2011 | pages: 108
Trail bridges not only provide convenient access to the national forests for hikers or packstock, but also can protect fragile riparian ecosystems. But. trail bridges can be difficult—in some cases, dangerous—to build. This report includes the results of controlled tests and case studies of field installations of fiber-reinforced polymer bridges. Fiber-reinforced polymer trail bridges are lighter and easier to assemble than traditional bridges built from wood or steel. At some remote sites, the advantages of light weight and ease of assembly may make fiber-reinforced polymer trail bridges a better alternative than wood or steel bridges. Wood for bridges made from native materials may be in short supply at some remote sites. Care must be taken in transporting fiber-reinforced polymer materials, though. Fiber-reinforced polymer materials are easy to damage when they are being transported to the bridge site and when they are being assembled.
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I am looking for Composite Steel Deck Design Handbook - No. CDD2 of SDI
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Author: El-Zghayar, Elie A | Size: 6.28 MB | Format:PDF | Quality:Original preprint | Publisher: University of Central Florida, Orlando | Year: 2011 | pages: 147
Post-tensioning tendons in segmental bridge construction are often only anchored within the deviator and pier segments. The effectiveness of the post-tensioning (PT) system is therefore dependent on proper functioning of the anchorages. On August 28, 2000, a routine inspection of the Mid-Bay Bridge (Okaloosa County, Florida) revealed corrosion in numerous PT tendons. Moreover, one of the 19-strand tendons was completely slacked, with later inspection revealing a corrosion-induced failure at the pier anchor location. Anchorage failure caused all PT force to transfer to the steel duct located within the pier segment that in turn slipped and caused the tendon to go completely slack. After the application of PT force, the anchorage assembly and steel pipes that house the tendon are filled with grout. These short grouted regions could, in the event of anchorage failure, provide a secondary anchorage mechanism preventing the scenario mentioned above from occurring. This paper presents the results of a full-scale experimental investigation on anchorage tendon pullout. The study focuses on the length required to develop the in-service PT force within the pier segment grouted steel tube assembly. Seven, twelve, and nineteen 0.6 inch diameter strand tendons with various development lengths were considered. Recommendations for pier section pipe detailing and design will be discussed.
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Author: Pokharel, Sanat Kumar | Size: 3.54 MB | Format:PDF | Quality:Original preprint | Publisher: University of Kansas, Lawrence | Year: 2011 | pages: 70
Soil nail walls are a widely used technology for retaining vertical and nearly vertical cuts in soil. A significant portion of the cost of soil nail wall construction is related to the construction of a reinforced concrete face. The potential for use of a flexible facing design for soil nail walls to replace reinforced concrete facing was evaluated using three-dimensional finite difference modeling and physical testing of a 1.5 meter by 1.5 meter unit cell of a soil nail wall in clay. A steel mesh form of flexible facing was used as a substitute for concrete. The finite difference model predicted large vertical and horizontal deformations for surcharges of approximately 5 psi. In the physical testing, the flexible facing products performed well with regard to strength, but the facing experienced large vertical and horizontal deformations that were consistent with the numerical modeling. Based on these results, it is recommended that use of flexible facing as a substitute for reinforced concrete be limited to non-critical structures where large vertical and horizontal deformations are acceptable.
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Performance load testing and structural adequacy evaluation of road bridge decks
Author: Jamtsho, L | Size: 4.68 MB | Format:PDF | Quality:Original preprint | Publisher: Queensland University of Technology | Year: 2011 | pages: 188
Many ageing road bridges, particularly timber bridges, require urgent improvement due to the demand imposed by the recent version of the Australian bridge loading code, AS 5100. As traffic volume plays a key role in the decision of budget allocations for bridge refurbishment/ replacement, many bridges in low volume traffic network remain in poor condition with axle load and/ or speed restrictions, thus disadvantaging many rural communities. This thesis examines an economical and environmentally sensible option of incorporating disused flat rail wagons (FRW) in the construction of bridges in low volume, high axle load road network. The constructability, economy and structural adequacy of the FRW road bridge is reported in the thesis with particular focus of a demonstration bridge commissioned in regional Queensland. The demonstration bridge comprises of a reinforced concrete slab (RCS) pavement resting on two FRWs with custom designed connection brackets at regular intervals along the span of the bridge. The FRW-RC bridge deck assembly is supported on elastomeric rubber pads resting on the abutment. As this type of bridge replacement technology is new and its structural design is not covered in the design standards, the in-service structural performance of the FRW bridge subjected to the high axle loadings prescribed in AS 5100 is examined through performance load testing. Both the static and the moving load tests are carried out using a fully laden commonly available three-axle tandem truck. The bridge deck is extensively strain gauged and displacement at several key locations is measured using linear variable displacement transducers (LVDTs). A high speed camera is used in the performance test and the digital image data are analysed using proprietary software to capture the locations of the wheel positions on the bridge span accurately. The wheel location is thus synchronised with the displacement and strain time series to infer the structural response of the FRW bridge. Field test data are used to calibrate a grillage model, developed for further analysis of the FRW bridge to various sets of high axle loads stipulated in the bridge design standard. Bridge behaviour predicted by the grillage model has exemplified that the live load stresses of the FRW bridge is significantly lower than the yield strength of steel and the deflections are well below the serviceability limit state set out in AS 5100. Based on the results reported in this thesis, it is concluded that the disused FRWs are competent to resist high axle loading prescribed in AS 5100 and are a viable alternative structural solution of bridge deck in the context of the low volume road networks.
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Improved Corrosion-Resistant Steel for Highway Bridge Construction
Author: Fletcher, Fred B | Size: 2.63 MB | Format:PDF | Quality:Original preprint | Publisher: Federal Highway Administration | Year: 2011 | pages: 94
Alloy steels with 9, 7, and 5 percent chromium (Cr) were designed to reduce the cost of ASTM A1010 steel containing 11 percent Cr. Additions of 2 percent silicon (Si) and/or 2 percent aluminum (Al) were made. The experimental steels could be heat treated to achieve the strength needed for bridges. However, only the ASTM A1010 steel exhibited sufficient impact toughness to be a candidate for bridge construction. The mechanical properties of the experimental steels are not suitable for bridge construction, although they are substantially more corrosion resistant than the conventional weathering steel, ASTM A588. When studied in the laboratory using cyclic corrosion tests, all of the steels exhibited a relatively linear rate of corrosion with increasing cycle number. As the Cr content decreased, the corrosion rate increased. The corrosion rate of the ASTM A1010 steel was one-tenth of the rate of the ASTM A588 steel. Si was detrimental to corrosion resistance, while Al was beneficial. The corrosion behavior was not a function of the steel yield strength. As the cyclic corrosion cycles increased, the proportion of oxyhydroxide corrosion product akaganeite declined and was replaced by maghemite, goethite, and lepidocrocite. However, the 11 percent Cr steels contained significantly less maghemite than the steels with lower Cr content. The 9 percent Cr, 7 percent Cr plus 2 percent Si, and 7 percent Cr plus 2 percent Al steels were exposed for 1 year on the heavily salted Moore Drive Bridge in Rochester, NY. Their corrosion rates were approximately one-half the rate of ASTM A588 weathering steel. The rust composition was similar for all three experimental steels. Life-cycle cost analyses examined the benefits of using a maintenance-free corrosion-resistant steel instead of regularly repainting a conventional steel bridge girder. By the 20th year of service, the probability is over 90 percent that the ASTM A1010 steel girder is less expensive. After 40 years, it becomes certain that the ASTM A1010 steel girder is cheaper than the painted conventional steel.
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Dikmen, U. (2009). “Statistical correlations of shear wave velocity and penetration resistance for soils,” Journal of Geophysics and Engineering, 6, 61-72.
This major revision of a bestselling text shows that soil is three-dimensional and dynamic. This concept is developed in the first two chapters and is built on throughout the book. Chapters 3 through 7 explore soil physical properties and water, with expanded coverage of tillage and traffic and an increased emphasis on water and wind erosion processes. Chapters 8 through 11 discuss the biological aspects of soils as well as their mineralogical and chemical properties. In Chapters 12 through 15, the general area of soil fertility and fertilizer use is covered. Other chapters examine soil genesis, taxonomy, geography, land use and soil survey, and land use interpretations. Finally in chapter 20, the importance of nonagronomic factors in the food population problem are discussed. Both English and metric units are used for crop yields, new figures and tables are included, summary statements are given at the end of the more difficult sections and at the end of each chapter, and non-agricultural examples and several computer applications are provided for reference.
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Large scale structural optimization: Computational methods and optimization algorithms
Author: M. Papadrakakis, N. D. Lagaros, Y. Tsompanakis, V. Plevris | Size: 2.5 MB | Format:PDF | Quality:Original preprint | Publisher: Archives of Computational Methods in Engineering, Volume 8, Issue 3 | Year: September 2001 | pages: 239-301 | ISBN: 1886-1784
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