U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
This magazine is an archived publication and may contain dated technical, contact, and link information.
|Publication Number: FHWA-HRT-08-004 Date: May/Jun 2008|
Publication Number: FHWA-HRT-08-004
Issue No: Vol. 71 No. 6
Date: May/Jun 2008
Below are brief descriptions of products recently published online by the Federal Highway Administration's (FHWA) Office of Research, Development, and Technology. Some of the publications also may be available from the National Technical Information Service (NTIS). In some cases, limited copies are available from the Research and Technology (R&T) Product Distribution Center.
When ordering from NTIS, include the NTIS publication number (PB number) and the publication title. You also may visit the NTIS Web site at www.ntis.gov to order publications online. Call NTIS for current prices. For customers outside the United States, Canada, and Mexico, the cost is usually double the listed price. Address requests to:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Toll-free number: 800-553-NTIS (6847)
Address requests for items available from:
Federal Highway Administration
R&T Product Distribution Center, HRTM-03
For more information on R&T publications from FHWA, visit FHWA's Web site at www.fhwa.dot.gov, the Turner-Fairbank Highway Research Center's Web site at www.fhwa.dot.gov/research/tfhrc/, the National Transportation Library's Web site at http://ntl.bts.gov, or the OneDOT information network at http://dotlibrary.dot.gov.
Publication No. FHWA-HRT-08-009
With the mission of accelerating infrastructure innovations, the December 2007 issue of FHWA’s Focus newsletter features articles on “The ABCs of a Rapid Bridge Replacement in Utah,” “SPMTs: Your Guide to Accelerated Bridge Construction,” “FHWA’s 2008 Accelerated Bridge Construction Conference: On the Fast Track to Success,” and “A Roadmap to Transportation System Preservation Research.” It also includes information on Excellence in Highway Design 2008 and the SHRP 2 International Symposium on Nondestructive Testing. The newsletter also contains the popular highway technology calendar, which lists upcoming events providing opportunities to learn more about infrastructure-related products and technologies.
The December issue of the newsletter is available online at www.fhwa.dot.gov/publications/focus/07dec/index.cfm.
Publication No. FHWA-HRT-04-097
This manual documents the development of an elastoplastic damage model for wood, as used in roadside safety structures, and its implementation into LS-DYNA, a commercially available finite element code. The manual details the theory of the wood material model, describes the LS-DYNA input and output formats, and provides example problems for use as learning tools. FHWA originally developed this material model to predict the dynamic performance of wood components used in roadside safety structures after motor vehicle collisions. However, it is applicable for all varieties of wood with appropriate material coefficients. For example, the manual offers models for default material coefficients for two wood varieties: southern yellow pine and Douglas-fir.
The companion report to this manual is the Evaluation of LS-DYNA Wood Material Model 143 (FHWA-HRT-04-096).
The manual is available online at www.fhwa.dot.gov/publications/research/safety/04097/index.cfm . Limited copies are available from FHWA’s R&T Product Distribution Center. The document is also available from NTIS under order number PB2006-101279.
Publication No. FHWA-HRT-07-039
Infrastructure deterioration, which includes corrosion of reinforcing steel in concrete bridges, results in a major economic and societal cost to the United States. For the past 30 years, specifications have called for epoxy-coated reinforcement (ECR) steel for reinforced concrete bridges exposed to deicing salts and coastal environments. However, premature corrosion-induced cracking of marine bridge substructures in Florida indicate that ECR is of little benefit for this type of exposure. In addition, although ECR has performed well in northern bridge decks for more than 30 years, the degree of resistance to long-term corrosion is uncertain for major structures with design lives of 75–100 years. This concern, combined with increased use of life-cycle cost analysis in project planning and materials selection, has generated renewed interest in corrosion-resistant reinforcements, and stainless steels in particular.
Researchers at the Florida Atlantic University and the Florida Department of Transportation recently evaluated alloys identified as candidate corrosion-resistant reinforcements. The alloys include MMFX-II™ (ASTM A1035); solid stainless steels 3Cr12 (UNS-S41003), 2201LDX (ASTM A955-98), 2205 (UNS 31803), and two 316L (UNS S31603) alloys; and two 316 stainless steel-clad black bar products. The researchers included black bar (ASTM A615) reinforcement for comparison purposes. Testing methods included three types of short-term exposures: (1) a previously developed method that involves cyclic exposure to synthetic pore solution (SPS) with incrementally increasing chlorides and then to moist air; (2) anodic potentiostatic exposure in SPS with incrementally increasing chlorides; and (3) potentiodynamic polarization scans in saturated calcium hydroxide at different chloride concentrations.
Long-term exposures involve four specimen types: (1) simulated deck slabs, (2) three-bar columns, (3) macrocell slab specimens, and (4) field columns. Specimen types (1) and (3) are being cyclically wet-dry ponded with a sodium chloride solution and are intended to simulate northern bridge decks exposed to deicing salts. Alternatively, types (2) and (4) are partially submerged continuously, the former in a sodium chloride solution and the latter at a coastal marine site in Florida. This report details findings from the initial 3 years of this 5-year project.
This document is available online at www.fhwa.dot.gov/publications/research/infrastructure/bridge/07039/index.cfm. Limited copies are available from FHWA’s R&T Product Distribution Center. The document also is available from NTIS under order number PB2007-112639.
Publication No. FHWA-HRT-07-041
In this research project, the West Virginia University Constructed Facilities Center and Institute for the History of Technology and Industrial Archaeology teamed up to develop means and methods to strengthen wooden superstructure components of historic covered bridges using glass fiber reinforced polymer (GFRP) composite materials. The strengthening methods developed in this project conform to the U.S. Secretary of the Interior’s Standards and Guidelines for Archeology and Historic Preservation.
Specifically, the study conducted tension and bending tests to establish the bond strength of GFRP rebars embedded in wood, and to establish the bending strength and stiffness of large-scale floor beams reinforced with GFRP pultruded plates and GFRP rebars. In addition, researchers developed methods to enhance the shear capacity of large-scale floor beams reinforced with GFRP-pultruded plates bonded on edge in narrow, prerouted vertical slots. The GFRP rebars were developed to be used specifically as axial reinforcement for truss members, while the GFRP plates were developed to increase the bending and shear capacity of floor beams.
The test results showed that bonded-in GFRP rebars performed well with pullout force and bond strength, and the strength and stiffness of GFRP floor beams improved significantly. Although the researchers expected the shear strength to improve considerably with the addition of the GFRP plates placed on edge (resulting in a flitched beam), the shear capacity decreased slightly. Because the researchers severely checked the flitched beams, the beams’ shear strength suffered more degradation when compared to the solid control specimen.
In addition, research included investigation of several methods of concealing the reinforcement. One successful method took advantage of routing a member on the bottom face and bonding a GFRP plate with an integrated veil to match the wood grain and color of the original aged wood.
This TechBrief is available online at www.tfhrc.gov/structur/pubs/07041/index.htm. The report also is available from NTIS under order number PB2007-103714.
Publication No. FHWA-HRT-07-043
This study evaluates 11 systems combining ECR with another corrosion protection system using the rapid macrocell, Southern Exposure, cracked beam, and linear polarization resistance tests. The systems include bars that are pretreated with zinc chromate to improve the adhesion between the epoxy and the reinforcing steel; two epoxies with improved adhesion to the reinforcing steel; one inorganic corrosion inhibitor calcium nitrite; two organic corrosion inhibitors; an epoxy-coated bar with a primer containing microencapsulated calcium nitrite; three epoxy-coated bars with improved adhesion combined with the corrosion inhibitor calcium nitrite; and multiple-coated bars with an initial 50-micrometer (2-mil) coating of 98 percent zinc and 2 percent aluminum, followed by a conventional epoxy coating. The study also compares the systems with conventional uncoated reinforcement and conventional ECR.
The results represent findings obtained during the first half of a 5-year study that includes longer term ASTM G 109 and field tests. In the short-term tests used to date, the epoxy coatings evaluated provide superior corrosion protection to the reinforcing steel. The results also indicate that the bars will continue to perform well in the longer term, although the tests do not evaluate the effects of long-term reductions in the bond between the epoxy and the reinforcing steel. The corrosion rate on the exposed regions of damaged ECR is somewhat higher than the average corrosion rate on the surface of uncoated reinforcement subjected to similar exposure conditions.
The use of concrete with a reduced water-cement ratio improves the corrosion performance of both conventional and ECR in uncracked concrete but has little effect in cracked concrete. Increased adhesion between the epoxy and reinforcing steel provides no significant improvement in the corrosion resistance of ECR. It appears that corrosion inhibitors in concrete and the primer coating containing microencapsulated calcium nitrite improve the corrosion resistance of the epoxy-coated steel in uncracked concrete, but not in cracked concrete. The zinc coating on the multiple-coated bars acts as a sacrificial barrier and provides some corrosion protection to the underlying steel in both uncracked and cracked concrete. The evaluation of the degree of protection, however, is currently not available.
This document is available online at www.fhwa.dot.gov/bridge/pubs/07043. Limited copies are available from FHWA’s R&T Product Distribution Center. The document also is available from NTIS under order number PB2007-111508.
Publication No. FHWA-HRT-07-044
ECR is the principal concrete reinforcing material currently used in corrosive environments in the United States. This study evaluates methods for making ECR more corrosion resistant by using multiple corrosion protection strategies in bridge decks, as well as for bridge members in marine environments where abundant salt, moisture, and high temperatures are prevalent.
After conducting research in laboratory and field tests, researchers will use the results of this study to compare the performance of the corrosion protection systems on the basis of chloride threshold, corrosion rate, life expectancy, and cost-effectiveness. The study also evaluates fusion-bonded thermoset ECR in conjunction with inorganic and organic corrosion inhibitors, bars coated with zinc prior to the application of epoxy, and chemical pretreatments and epoxy formulations that increase the adhesion of the epoxy coating to the reinforcing steel.
This TechBrief is available online at www.fhwa.dot.gov/bridge/pubs/07044/index.cfm.