This report presents the results of a round robin study to prepare precision estimates for AASHTO T148 test method used for determining the length of a core drilled from a concrete pavement or structural element. The materials for the round robin included six concrete cores taken from LTPP test sections of FHWA. The cores were either 4” or 6” in diameter with varying length in the range of 4” to 12”. The cores were representative of different FHWA LTPP concrete pavement test sections from which they were removed. The apparatus for measuring the length of the cores was a 3-point callipering device specified in AASHTO T148 test method. The six specimens were carried around to eleven laboratories and the length measurements were collected. The results indicated that the repeatability and reproducibility precisions are significantly different for different core diameters. Therefore, the precision estimates were prepared separately for 4” and 6” diameter specimens.
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Determining Guidelines for Ramp and Interchange Spacing
Author: Ray, Brian L Kittelson and Associates, Incorporated Schoen, James Kittelson and Associates, Incorporated Jenior, Pete Kittelson and Associates, Incorporated Knudsen, Julia Kittelson and Associates, Incorporated Porter, Richard J University of Utah, Salt Lake City Leisch, Joel P Mason, John Roess, Roger | Size: 5.70 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2010 | pages: 238 | ISBN: -
This project considered the effects of geometry, traffic operations, safety, signing, and other factors to develop guidelines for understanding the considerations that influence minimum ramp and interchange spacing values. Phase I included conducting a literature search and other information gathering activities, developing a work plan to assess the impact of ramp spacing on traffic operations and safety, and developing a framework for the research guidelines. Phase II included creating microscopic simulation models of closely-spaced ramp combinations calibrated with field data, constructing a crash database and developing crash prediction models, developing a set of guidelines for ramp and interchange spacing, and recommending changes to major resource documents within the transportation profession. As a final product, the team wrote NCHRP Report 687, "Guidelines for Ramp and Interchange Spacing," to assist users as they consider new or modified ramps and interchanges.
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Adapting Specification Criteria for Simple Performance Tests to HMA Mix Design
Author: Witczak, M W Arizona State University, Tempe El-Basyouny, M Arizona State University, Tempe Uzan, J Arizona State University, Tempe | Size: 1.99 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2011 | pages: 64 | ISBN: -
The objective of this project was to develop a software program for evaluating the potential performance of hot mix asphalt (HMA) mix designs in combination with their intended pavement structures. This "Program for Integrated Analysis of HMA Mix And Structural Designs" is coded as a Microsoft Excel spreadsheet (9-33A(Sep10).xlsm) and supporting files. The program incorporates the Mechanistic-Empirical Pavement Design Guide (MEPDG) spreadsheet solutions developed in NCHRP Projects 9-19 and 9-22. Predictions of permanent deformation (rutting) and fatigue cracking are made on the basis of the estimated HMA dynamic modulus, E*; thermal cracking predictions are based on estimates of the HMA creep compliance, D. The program will serve as a multi-purpose tool for HMA mix and structural design engineers. First, it provides an easy graphical check that a prospective job mix formula (JMF) falls within the acceptable limits of air voids and effective binder volume established by the project’s HMA specification. Second, using powerful, pre-solved solutions of the MEPDG, it provides rapid estimates of the performance of the JMF over the design life of the HMA pavement and whether the JMF will satisfy specific pavement distress criteria established by the agency. Third, it can test “what-if” scenarios by estimating how changes in the JMF, pavement structure, or both may affect performance. Finally, it can be used in forensic investigations of pavement distresses, by assessing the potential contributions of the HMA and pavement structure to distress development before any testing is conducted. This report presents (1) a description of the program’s inputs and outputs, (2) a brief review of the underlying performance prediction models, and (3) examples illustrating the use of the program to analyze specific mix-structure combinations. Technical familiarity with the MEPDG design principles, the E* Simple Performance Test (SPT) Specification Criteria Program, and the Quality-Related Specification Software (QRSS) will enhance the user’s understanding of the program.
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Cast-in-Place Concrete Connections for Precast Deck Systems
Author: French, C E | Size: 17.88 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2011 | pages: 782 | ISBN: -
This report contains recommended design specifications, construction specifications, and five illustrative examples of durable cast-in-place (CIP) reinforced concrete connections for precast deck systems that emulate monolithic construction, considering issues including speed of construction, durability, and fatigue. Included in the report is the supporting research that led to these recommendations. This research focused on systems that reduce the need to place and remove formwork thus accelerating on-site construction and improving safety. The three systems considered to accomplish these objectives were: (1) a precast composite slab span system (PCSSS) for short to moderate span structures, (2) full-depth prefabricated concrete decks, and (3) deck joint closure details (e.g., decked-bulb-tee (DBT) flange connections) for precast prestressed concrete girder systems for long span structures. Depending on the system, the connections are either transverse (i.e., across the width of the bridge) or longitudinal (i.e., along the length of the bridge). The first system, PCSSS, is an entire bridge system; whereas the other two systems investigated in the project represented transverse and longitudinal joint details to transfer moment and shear in precast deck panels and flanges of decked bulb tees. Two types of connection concepts were explored with these details, looped bar details and two layers of headed bar details.
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Evaluation of Bridge Scour Research: Pier Scour Processes and Predictions
Author: Ettema, Robert University of Wyoming, Laramie Constantinescu, George University of Iowa, Iowa City Melville, Bruce University of Auckland | Size: 4.42 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2011 | pages: 195 | ISBN: -
This report explores the current state of knowledge regarding bridge pier scour, assesses several methods for design estimates of scour depth, examines a structured methodology for scour depth estimation for design purposes, and highlights aspects of pier scour in need of potential further research. It focuses particularly on research information obtained since 1990, showing that this information provides considerable new insights that compel the need to change the design method currently recommended by the principal authoritative design guides and used widely by bridge engineering practitioners. Additionally, it indicates that several important aspects of pier scour processes remain inadequately understood and not yet incorporated into design methods.
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Cost-Effective Connection Details for Highway Sign, Luminaire, and Traffic Signal Structures
Author: Roy, S Lehigh University Park, Y C Lehigh University Sause, R Lehigh University Fisher, J W Lehigh University Kaufmann, E J Lehigh University | Size: 9.73 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2011 | pages: 236 | ISBN: -
This report documents the results of a comprehensive experimental and analytical study that evaluated fatigue performance of several critical welded connections in the highway sign, signal and high-level luminaire support structures. In this study, infinite life fatigue resistance of connection details in the existing inventory was established and new cost-effective fatigue resistant connections were developed. About 80 full size galvanized specimens of sign, signal and high-level luminaire support structures containing different welded connections were fatigue tested. Using parametric Finite Element Analyses (FEA) of 3D models verified by test data, fatigue performance of the connections in both finite and infinite life regimes were defined in terms of fatigue stress concentration factors over the range of applicable geometric dimensions. The study demonstrated that tube-to-transverse plate connections are the most fatigue critical details in the subject structures. Increasing the stiffness of the transverse plate is the most cost-effective means of improving fatigue resistance of this connection. Groove welded connections with smaller opening in the plate exhibits largest fatigue resistance. Sharper bend radius and less number of sides reduce fatigue threshold of connections in multi-sided sections. Based on these research findings, new specification recommendations were proposed for revision to the existing AASHTO specifications.
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Simulation of Stochastic Processes by Spectral Representation
Appl. Mech. Rev. -- April 1991 -- Volume 44, Issue 4, 191 (14 pages)
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DIN 4124: Title (English): Excavations and trenches - Slopes, planking and strutting breadths of working spaces.
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This circular explores the state of the practice and representative applications on the use of inclinometer systems for measuring ground deformation and performance of geotechnical design elements on transportation projects. The report examines inclinometer components and installation details, and includes information on planning inclinometer installation, acquiring and displaying data, and interpreting test results.
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Geophysical Methods Commonly Employed for Geotechnical Site Characterization
Author: Anderson, Neil L | Size: 1.35 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2008 | pages: 44
This circular offers an overview of 12 geotechnical geophysical methods that are commonly applied to transportation projects. Geotechnical geophysics is the application of geophysics to geotechnical engineering problems; such investigations normally extend to total depths of less than 300 ft. Geotechnical geophysical surveys are performed on the ground surface, within boreholes and water, and from the air. Using illustrations and brief examples, commonly employed geotechnical geophysical methods are described. Through summary tables and brief discussions, common applications of engineering geophysics are presented. Chapters are devoted to the selection of appropriate geophysical methods and geophysical contractors, respectively. Use of geophysics by transportation agencies is reviewed through a summary of NCHRP Synthesis 357: "Use of Geophysics for Transportation Projects" (Sirles, 2006). A detailed description of applications of geophysical methods to highway-related problems may be found at www.cflhd.gov/agm/index.htm.
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