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January/February 2008 · Vol. 71 · No. 4
January/February 2008
Communication Product Updates
Compiled by Zac Ellis of FHWA's Office of Research and Technology Services
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
Telephone: 703-605-6000
Toll-free number: 800-553-NTIS (6847)
Address requests for items available from the R&T Product Distribution Center to:
R&T Product Distribution Center, HRTS-03
Federal Highway Administration
9701 Philadelphia Court, Unit Q
Lanham, MD 20706
Telephone: 301-577-0818
Fax: 301-577-1421
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.tfhrc.gov, the National Transportation Library's Web site at http://ntl.bts.gov, or the OneDOT information network at http://dotlibrary.dot.gov.
Compilation and Evaluation of Results From High-Performance Concrete Bridge Projects, Volume I: Final Report
Publication No. FHWA-HRT-05-056
In 1993 FHWA initiated a national program to implement the use of high-performance concrete (HPC) in bridges. The program included construction of demonstration bridges in each FHWA region and dissemination of the technology and results at showcase workshops. Initially, 19 bridges in 14 States were included in the program. Since then, other States have begun using HPC in various bridge elements.
The bridges are located in different climatic regions of the United States and used different types of superstructures. They demonstrated practical applications and provided opportunities to learn more about the placement and behavior of HPC. In addition, the bridges' instrumentation enabled regions to monitor short- and long-term performances and measure concrete material properties.
Appendixes for this volume appear in Compilation and Evaluation of Results From High-Performance Concrete Bridge Projects, Volume II: Appendixes (FHWA-HRT-05-057).
Limited copies are available from FHWA's R&T Product Distribution Center. The document also is available from NTIS under order number PB2007-105581.
Compilation and Evaluation of Results From High-Performance Concrete Bridge Projects, Volume II: Appendixes
Publication No. FHWA-HRT-05-057
This report details the four parts of FHWA's national HPC program. The first part of the program collected and compiled information from each joint State-FHWA HPC bridge project and other HPC bridge projects. The compilation is available on a CD-ROM and includes information on the benefits of HPC, costs, structural design, specified concrete properties, concrete mix proportions, measured properties, associated research projects, sources of data, and specifications.
The second part of the program reviewed the American Association of State Highway and Transportation Officials' (AASHTO) Standard Specifications for Transportation Materials and Methods of Sampling and Testing, Standard Specifications for Highway Bridges, Load and Resistance Factor Design (LRFD) Bridge Design Specifications, and LRFD Bridge Construction Specifications for provisions that directly affect the use of HPC.
The third part of the program developed proposed revisions to the AASHTO specifications where sufficient research results existed to support the revisions. The report includes proposed revisions to 15 material specifications, 14 test methods, 30 articles of the standard design specifications, 17 articles of the LRFD design specifications, and 16 articles of the LRFD construction specifications. In addition, a new materials specification for combined aggregates, a new test method for slump flow, and a revision to the FHWA definition of HPC are proposed.
The fourth part of the project developed specific recommendations for research to support needed changes in the specifications. The report also recommends six research problem statements related to concrete materials and four related to structural design.
The final report associated with these appendixes is Compilation and Evaluation of Results From High-Performance Concrete Bridge Projects, Volume I: Final Report (FHWA-HRT-05-056).
Limited copies are available from FHWA's R&T Product Distribution Center. The document also is available from NTIS under order number PB2007-105582.
Users Manual for LS-DYNA Concrete Material Model 159
Publication No. FHWA-HRT-05-062
This is the first of two manuals that document an elasto-plastic damage model with rate effects developed for concrete and implemented into LS-DYNA, a finite element code. This manual explores the theory of the concrete material model, describes the required input format, and includes sample problems for use as a learning tool. In addition, the manual provides a default material property input option for normal strength concrete. Originally developed for roadside safety applications such as concrete bridge rails and portable barriers impacted by vehicles, the model also applies to other dynamic applications. The companion report to this manual is titled Evaluation of LS-DYNA Concrete Material Model 159 (FHWA-HRT-05-063).
Limited copies are available from FHWA's R&T Product Distribution Center. The document also is available from NTIS under order number PB2007-109573.
Evaluation of LS-DYNA Concrete Material Model 159
Publication No. FHWA-HRT-05-063
This manual documents evaluation of the concrete material model, including selection of the concrete model input parameters. The report details model evaluations through correlations with test data: drop tower impact of 1/3-scale beams (plain and reinforced), bogie vehicle impact of full-scale reinforced beams, pendulum impact of bridge rails, and quasi-static loading of a safety-shaped barrier. The companion report to this manual is titled Users Manual for LS-DYNA Concrete Material Model 159 (FHWA-HRT-05-062).
This document is available online at www.tfhrc.gov/safety/pubs/05063/05063.pdf. Limited copies are available from FHWA's R&T Product Distribution Center.
Freight Technology Assessment Tool User Guide
Publication No. FHWA-HOP-06-110
FHWA works with its partners to evaluate potential technology solutions to improve the reliability, efficiency, and security of the freight transportation system. Technology evaluation is a complex process requiring analysis of many factors, including freight transportation needs, supply chain performance, costs, and benefits. Not surprisingly, the complexity increases as the number of criteria and parties involved rises.
Recognizing the need for evaluation tools to sift through technology options, FHWA developed the Freight Technology Assessment Tool (FTAT) and a supplemental user guide. FTAT aims to give decisionmakers the information and tools needed to invest wisely and prioritize future projects. Making good investment choices for the transportation system is critical to enhancing the Nation's economic productivity and global connectivity.
This document is available online at http://ops.fhwa.dot.gov/freight/publications/ftat_user_guide/ftat_user_guide.pdf. For additional information, please contact Transportation Specialist Randy Butler at 202-366-9215 or randy.butler@fhwa.dot.gov.
Freeze-Thaw Resistance of Concrete With Marginal Air Content (TechBrief)
Publication No. FHWA-HRT-06-118
Freeze-thaw resistance is a key durability factor for concrete pavements. Recommendations for the air void system parameters are normally 6 ± 1 percent total air and a spacing factor of ≤ 0.20 millimeter (0.008 inch); however, recent laboratory studies proved that some concretes without these commonly accepted thresholds offer good freeze-thaw resistance.
This study evaluated the freeze-thaw resistance of several marginal air void mixes with two types of air-entraining admixtures, a Vinsol® resin and a synthetic admixture. To conduct the study, researchers used rapid cycles of freezing and thawing in plain water, with no deicing salts.
For the specific materials and concrete mixture proportions used in this project, the marginal air mixes (concretes with fresh air contents of 3.5 percent or higher) presented an adequate freeze-thaw performance with a Vinsol resin-based, air-entraining admixture. The synthetic admixture used in this study did not perform as well as the Vinsol resin admixture.
This document is available online at www.fhwa.dot.gov/pavement/concrete/pubs/06118. Limited copies are available from FHWA's R&T Product Distribution Center.
Pedestrian and Bicyclist Intersection Safety Indices: Final Report
Publication No. FHWA-HRT-06-125
The primary objective of this study was to develop safety indices to enable engineers, planners, and other practitioners to prioritize intersection crosswalks and approaches with respect to pedestrian and bicyclist safety. The study collected data on pedestrian and bicyclist crashes, conflicts, avoidance maneuvers, and subjective ratings of intersection video clips by pedestrian and bicycle experts. Researchers selected 68 intersection crosswalks for the pedestrian analysis from the following cities: San José, CA; Miami-Dade County, FL; and Philadelphia, PA. The bicycle analysis included 67 intersection approaches from Gainesville, FL; Eugene and Portland, OR; and Philadelphia, PA.
The study developed prioritization models based on expert safety ratings and behavioral data. Indicative variables in the pedestrian safety index model included type of intersection control (signal or stop sign), number of through lanes, 85th-percentile vehicle speed, main street traffic volume, and area type. Indicative variables in the bicycle safety models (for through, right-turn, and left-turn bike movements) included the presence of various combinations of bicycle lanes, main and cross street traffic volumes, number of through lanes, presence of onstreet parking, main street speed limit, presence of a traffic signal, number of turn lanes, and others. A user-friendly guide will help practitioners use the safety indices to identify which crosswalk and intersection approaches have the highest priority for indepth pedestrian and bicyclist safety evaluations and subsequently use other tools to identify and address potential safety problems.
This document is available online at www.tfhrc.gov/safety/pedbike/pubs/06125/index.htm. Limited copies are available from FHWA's R&T Product Distribution Center. The document also is available from NTIS under order number PB2007-109548.
The Use of Lithium to Prevent or Mitigate Alkali-Silica Reaction in Concrete Pavements and Structures
Publication No. FHWA-HRT-06-133
Alkali-silica reaction (ASR) was first identified as a form of concrete deterioration in the late 1930s and early 1940s (T.E. Stanton 1940). Approximately 10 years later, researchers discovered that lithium compounds can control expansion due to ASR. Since then, there has been an increased interest in using lithium technologies to both control ASR in new concrete and retard the reaction in existing ASR-affected structures.
This facts book provides information on lithium's origin, properties, and applications. The report discusses the mechanism of ASR, together with methods of testing to identify potential ASR aggregates, and presents traditional methods for minimizing the risk of damaging ASR. Examples include avoiding reactive aggregates, controlling the levels of alkali in concrete, and using supplementary cementing materials such as fly ash, slag, and silica fume. The final two sections discuss the use of lithium first as an admixture for new concrete construction and second as a treatment for existing concrete structures affected by ASR.
This document is available online at www.fhwa.dot.gov/pavement/concrete/pubs/06133/index.cfm. Limited copies are available from FHWA's R&T Product Distribution Center. The document also is available from NTIS under order number PB2007-109549.
Strengthening Historic Covered Bridges to Carry Modern Traffic (TechBrief)
Publication No. FHWA-HRT-07-041
This document is a technical summary of an unpublished FHWA report, Strengthening Historic Bridges to Carry Modern Traffic (FHWA Contract No. DTFH61-00-C-00081), which is only available through NTIS. This TechBrief describes research from 2000-2004 on the use of glass fiber-reinforced polymer composites to strengthen wooden superstructure components of historic covered bridges.
At one time, the United States reportedly had as many as 14,000 covered bridges; fewer than 900 now remain. Under the National Historic Covered Bridge Preservation Program, FHWA provides funds for rehabilitation, restoration, and preservation of covered bridges. If the goal for a particular bridge is to strengthen it sufficiently to support today's vehicular traffic, a major engineering challenge arises. The research described in this TechBrief could help meet that challenge.
The TechBrief is available online at www.tfhrc.gov/structur/pubs/07041/index.htm. The NTIS accession number of the report covered in this TechBrief is PB2007-103714.
Other Articles in this issue:
Is Your Construction Project a Victim of Crime?
QuickZone: Modeling In the Zone
The Corporate Master Plan Shapes R&T Practice
January/February 2008 · Vol. 71 · No.3
