Technical Reports, Civil and Environmental Engineering

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Browsing Technical Reports, Civil and Environmental Engineering by Subject "Bridge decks"

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    Development and Evaluation of an Adhesively Bonded Panel-to-Panel Joint for a Fiber-Reinforced Polymer Bridge Deck System
    Liu, Zihong; Majumdar, Prasun K.; Cousins, Tommy; Lesko, John J. (Virginia Center for Transportation Innovation and Research, 2007-04-01)
    A fiber-reinforced polymer (FRP) composite cellular deck system was used to rehabilitate a historical cast iron thru-truss structure (Hawthorne Street Bridge in Covington, Virginia). The most important characteristic of this application is reduction in self-weight, which raises the live load-carrying capacity of the bridge by replacing the existing concrete deck with an FRP deck. This bridge is designed to an HL-93 load and has a 75-ft clear span with a roadway width of 22 ft. The panel-to-panel connections were accomplished using full width, adhesively (structural urethane adhesive) bonded tongue and groove splices with scarfed edges. To ensure proper construction, serviceability, and strength of the splice, a full-scale two-bay section of the bridge with three adhesively bonded panel-to-panel connections was constructed and tested in the Structures Laboratory at Virginia Tech. Test results showed that no crack initiated in the joints under service load and no significant change in stiffness or strength of the joint occurred after 3,000,000 cycles of fatigue loading. The proposed adhesive bonding technique was installed in the bridge in August 2006.
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    Performance of a Bridge Deck with Glass Fiber Reinforced Polymer Bars as the Top Mat of Reinforcement
    Phillips, Kimberly A.; Harlan, Matthew; Roberts-Wollmann, Carin L.; Cousins, Thomas E. (Virginia Center for Transportation Innovation and Research, 2005-06-01)
    The purpose of this research was to investigate the performance of glass fiber reinforced polymer (GFRP) bars as reinforcement for concrete decks. Today's rapid bridge deck deterioration is calling for a replacement for steel reinforcement. The advantages of GFRP such as its high tensile strength, light weight, and resistance to corrosion make it an attractive alternative to steel. The deck of one end-span of the Gills Creek Bridge was constructed with GFRP bars as the top mat and epoxy-coated steel bars as the bottom mat. Live load tests were performed in 2003, shortly after completion of construction, and again in 2004. In addition, tests were performed on the deck of the opposite end-span, which had all epoxy-coated steel reinforcing. The results of these tests were used to evaluate the girder distribution factors and impact factors of a GFRP reinforced bridge deck. In addition, a comparison of the results from the two test periods gives an indication of any changes in strains in the GFRP bars and if the deck is behaving differently than when first installed. The results were compared to the design standards specified by the American Concrete Institute in the Guide for the Design and Construction of Concrete Reinforced with FRP Bar to determine if the stresses in the deck were within the specified limits. The performances of the two end-spans were compared to determine if the GFRP reinforcement had any significant influence on overall bridge behavior. There were no significant differences in the behavior of the deck after 1 year of service and there was no visible cracking. The behavior of the two end-spans was similar, and the measured girder distribution factors were less than the AASHTO design recommendations. The impact factors were less than design values for the 2003 tests but higher than design values for the 2004 tests. Stresses in the GFRP reinforcing bars were much less than the design allowable stress and did not change significantly after 1 year of service. The strain gauges, vibrating wire gauges, and thermocouples in the bridge deck were monitored for approximately 1 year using a permanent data acquisition system. Daily, monthly, and long-term fluctuations in temperature and stresses were examined. The vibrating wire gauges were more reliable than the electrical resistance strain gauges, and the main influence on strain changes was temperature fluctuation. A cost/benefit analysis of using GFRP bars indicates their high initial costs are justified when compared to the costs of a concrete overlay.
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    Proof Testing a Bridge Deck Design with Glass Fiber Reinforced Polymer Bars as Top Mat of Reinforcement
    Jason K. Cawrse; Roberts-Wollmann, Carin L. (Virginia Center for Transportation Innovation and Research, 2003-06-01)
    The primary objective of this project was to test a full-scale prototype of a bridge deck design containing glass fiber reinforced polymer (GFRP) bars as the top mat of reinforcement. The test deck mimics the design of the deck of one span of the new bridge over Gills Creek on Rt. 668 in Franklin County, Virginia. The purpose of the tests was to verify the deck design and provide assurance that the deck will behave as expected. Aspects of the behavior of the bridge deck, such as failure load, failure mode, cracking load, crack widths, deflections, and internal stresses, were examined. Four tests were performed on the deck, all of which tested the deck in negative moment regions. The tests comprised two overhang tests, one test of the deck over an interior girder, and one test of a cantilever section of the composite deck and girder. The cantilever test modeled the deck in a continuous bridge over an interior support. From the tests, it was concluded that the design of the deck was quite conservative. The secondary objectives of this project were to comment on the construction of a bridge deck reinforced with GFRP bars, note the advantages and disadvantages, and critique the current state of the art of designing bridge decks with GFRP reinforcement. It was found that the advantages of construction with GFRP bars easily outweighed the disadvantages and that the placing of the top mat of GFRP bars was much easier than the placing of the bottom mat of steel bars. The state of the art for the design of bridge decks reinforced with GFRP bars was found to be generally conservative. Three primary criteria dictate the deck design: strength, allowable stresses in the GFRP bars, and crack widths. For this deck, the size and spacing of the transverse GFRP bars were governed by crack control criteria. In testing the deck, however, it was found that the measured crack widths were far smaller than the calculated widths. The measured bar stresses, after cracking, were below those calculated, and below the allowable for all but the cantilever test. The ultimate failure loads were between 3.7 and 7.6 times the design wheel load plus impact. All failures were due to punching shear and were between 91% and 149% of the predicted failure load. Current methods for calculating one-way shear grossly under-predicted capacity. The current design is safe and should prove to be low maintenance. Improvements in design approach, particularly for crack widths and one-way shear, could result in more economical designs in the future. Although current methods for calculating strength and serviceability requirement do not result in accurate predictions of behavior, they do result in conservative designs.
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    Summary Report on the Performance of Epoxy-Coated Reinforcing Steel in Virginia
    Weyers, Richard E.; Sprinkel, Michael M.; Brown, Michael C. (Virginia Center for Transportation Innovation and Research, 2006-06-01)
    From 1992 to 2006, the Virginia Transportation Research Council and its contract researchers conducted a long-term systematic series of investigations to evaluate the corrosion protection effectiveness of epoxy-coated reinforcement (ECR) and to identify and recommend the best and most cost-effective corrosion protection system for Virginia bridge decks. This report summarizes this research and subsequent efforts to implement alternative reinforcement. The work was conducted, and is reported, in this general order: review of historical performance of ECR, ECR performance in solutions and concrete, and preliminary field investigations; investigation of field performance of bridge decks built with ECR; assessment of alternative corrosion protection methods; development of probabilistic service life models for bridge decks and laboratory assessment of ECR cores extracted from bridge decks to determine service life extension; efforts to implement alternative reinforcement. The series of studies demonstrated that the epoxy coating on ECR naturally degrades in the highly alkaline moist environment within concrete. The subsequent loss of bond, coupled with the inevitable flaws in the coating induced by construction, leads to an estimated service life benefit of ECR of as little as 3 to 5 years. Further, non-critical decks, beams, and substructure elements not exposed to marine environments, particularly on secondary and rural routes, can be cost-effectively constructed and maintained using low-permeability concrete and black reinforcing bar. However, because the Federal Highway Administration requires the use of corrosion-resistant reinforcement, and because ECR cannot provide adequate corrosion protection for structures designed for a 100-year+ service life as currently recommended by FHWA, the report recommends that the Virginia Department of Transportation amend its specifications regarding the use of ECR to require the use of corrosion-resistant metallic reinforcing bars such as MMFX2, stainless steel clad, and solid stainless steel.