Download or read book Enhanced Analysis of Falling Weight Deflectometer Data for Use with Mechanistic empirical Flexible Pavement Design and Analysis and Recommendations for Improvements to Falling Weight Deflectometers written by Karim Chatti and published by . This book was released on 2017 with total page 297 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the efforts undertaken to review the status of falling weight deflectometer (FWD) equipment, data collection, analysis, and interpretation, including dynamic backcalculation, as they relate to the models and procedures incorporated in the Mechanistic-Empirical Pavement Design Guide. The work conducted in this project resulted in the following: Development of a backcalculation scheme (BACKLAVA) in the time domain using a quasi-static model (LAVA) as its forward solution and genetic algorithm (GA) as its search engine. BACKLAVA is a backcalculation algorithm for a constant asphalt concrete (AC) layer temperature. Development of a backcalculation scheme (BACKLAVAP) in the time domain using a quasi-static model (LAVAP) as its forward solution and GA as its search engine. BACKLAVAP is a backcalculation algorithm for a temperature profile in an AC layer. Development of a backcalculation scheme (BACKLAVAN) in the time domain using a quasi-static model (LAVAN) as its forward solution and GA as its search engine. BACKLAVAN is a backcalculation algorithm for a viscoelastic AC layer and a nonlinear base layer. Development of a backcalculation scheme (DYNABACK-VE) in the time domain using a time-domain viscoelastic dynamic model (ViscoWave-II) as its forward solution and a hybrid approach (GA and Levenberg-Marquardt algorithm) as its search engine. DYNABACK-VE is a backcalculation algorithm for a viscoelastic AC layer with temperature profile and linear unbound layers. Short list of recommendations for FWD equipment enhancements. The tools developed in this project are standalone applications that could be used on most computers.
Download or read book Using Falling Weight Deflectometer Data with Mechanistic empirical Design and Analysis written by Kurt D. Smith and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The need to accurately characterize the structural condition of existing pavements has increased with the recent development, release, and ongoing implementation of the Mechanistic-Empirical Pavement Design Guide (MEPDG). A number of different material inputs are required in the procedure, and it is important to adequately characterize and define them. The analysis of deflection data collected by the falling weight deflectometer (FWD) provides a quick and reliable way to characterize the properties of the paving layers, as well as to assess the load-carrying capacity of existing pavement structures. With the release of the new MEPDG, there is a pressing need to identify and evaluate the way that FWD testing is integrated into the new design procedure. Moreover, as highway agencies continue to implement the MEPDG, they need best practices guidance on how to effectively test existing pavement structures and interpret the results as part of a mechanistic-empirical pavement evaluation and rehabilitation process.
Download or read book Use of Falling Weight Deflectometer Multi load Data for Pavement Strength Estimation written by Y. Richard Kim and published by . This book was released on 2002 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this study is to develop a mechanistic-empirical method for assessing pavement layer conditions and estimating the remaining life of flexible pavements using multi-load level Falling Weight Deflectometer (FWD) deflections. A dynamic finite element program, incorporating a stress-dependent soil model, was developed to generate the synthetic deflection database. Based on this synthetic database, the relationships between surface deflections and critical pavement responses, such as stresses and strains in each individual layer, have been established. A condition assessment procedure for asphalt pavements that uses multi-load level FWD deflections has been developed using these relationships. The verification study was conducted using field data.
Download or read book Use of Falling Weight Deflectometer Multi Load Level Data for Pavement Strength Estimation written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this study is to describe a mechanistic-empirical approach to developing an analysis method for assessing pavement layer conditions and estimating the remaining life of flexible pavements using multi-load level Falling Weight Deflectometer (FWD) deflections. A dynamic finite element program, incorporating a stress-dependent soil model, was developed to generate the synthetic deflection database. Based on this synthetic database, the relationships between surface deflections and critical pavement responses, such as stresses and strains in each individual layer, have been established. A condition assessment procedure for pavement layers using multi-load level FWD deflections is presented in this study. The results indicate that the proposed procedure can estimate the base and subgrade layer conditions. However, large variations were observed in the relationships between the DBCI and desg values and the subgrade CBR values for aggregate base pavements. A FWD test with a load of 53 kN or less does not result in any apparent nonlinear behavior of the subgrade in aggregate base pavements. With regard to the condition assessment of the asphalt concrete (AC) layer, the AC layer modulus and the tensile strain at the bottom of the AC layer are found to be better indicators than the deflection basin parameter. The procedures for performance prediction of fatigue cracking and rutting are developed for flexible pavements. The drastically increasing trend in fatigue cracking with time may not be predicted accurately using the proposed procedure. Such trends may be due to the environmental effects and the inconsistent distress measurements. Predicted rut depths using both single and multi-load level deflections show good agreement with measured rut depths over a wide range of rutting potential. However, the procedure using single load level deflections consistently underpredicts the rut depths. This observation demonstrates that the rutting prediction procedure usin.
Download or read book Interpreting Data from the Falling weight Deflectometer written by and published by . This book was released on 1994 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Use of Falling Weight Deflectometer Data in Monitoring Flexible Pavement Systems written by NC. Jackson and published by . This book was released on 1989 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pavement performance studies are being conducted in the states of Nevada and Washington for the purpose of developing mechanistically based pavement design procedures for highways. A critical element of each of these studies is the statewide characterization of the pavement materials. The materials characterization process has included laboratory and field testing for 16 sites in Washington and 27 sites in Nevada.
Download or read book Use of Falling Weight Deflectometer Data for Assessing Pavement Structural Evaluation Values written by Tanveer Chowdhury and published by . This book was released on 1999 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structural evaluation can be very useful at the network level for project prioritization purposes. In the project priority ranking procedure of the Kansas Department of Transportation (KDOT), a pavement rating attribute, Pavement Structural Evaluation (PSE), is used. These ratings are subjective. his study outlines an approach based on the classical multiple regression analysis resulting in a better estimation of the PSE values using the results from the Falling Weight Deflectometer (FWD) tests and network-level distress survey. The regression models proposed in this study predict the decrease in PSE values by taking into account the FWD data, age, thickness, and distress levels of pavements, and very closely approximate the current PSE ratings obtained at the district level.
Download or read book Evaluation of the Falling Weight Deflectometer written by Ronald Netemeyer and published by . This book was released on 1997 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pavement Analysis written by Per Ullidtz and published by . This book was released on 1987 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides some simple methods for the analysis of pavements in order to describe their present condition and to predict their future condition. Functional and structural conditions of flexible and rigid highway and airfield pavements are treated.
Download or read book Dynamic Analysis of Falling weight Deflectometer Data written by Allen H. Magnuson and published by . This book was released on 1988 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: Falling-Weight Deflectometer data from three in-service pavement sections has been used to analyze dynamic response characteristics. The Analyzed data will be used later in the project along with computer predictions of pavement response to back-calculate engineering properties of pavements. The pavements had thicknesses of 1.5 in., 9 in., and 12 in., and two load levels were tested. The full pulse data is presented for the dropweight force and all seven surface displacement sensors. The analysis was performed in the frequency domain using frequency response functions computed from the pulse data. The frequency response functions were computed by dividing the Fast Fourier Transform (FFT) of the displacements by the FFI of the force. Magnitude and phase angles of the frequency response functions are presented. An undesirable oscillation was present in the frequency response functions. This was attributed to a discontinuity in the displacement pulses resulting from zero-packing in the FFT Program. The pulses have a non-zero "tail" value at the end of the 60 msec sample period which causes the discontinuity. The pulse "tail" may be due to drift, permanent deformation of the pavement, or premature truncation before the transient response had died out. A linear correction to the pulses that eliminated the discontinuity was applied to one test case. This eliminated the undesirable oscillation, giving the responses a more regular behavior similar to predicted theoretical responses. This correction should facilitate comparison studies of computed versus measured FWD responses.
Download or read book Dynamic Analysis of Falling Weight Deflectometer Data written by Boutros E. Sebaaly and published by . This book was released on 1986 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Falling Weight Deflectometer Relative Calibration Analysis written by and published by . This book was released on 1993 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nondestructive deflection testing with Falling Weight Deflectometers (FWDs) is a critical element of the pavement monitoring effort for the Long-Term Pavement Performance (LTPP) testing of the Strategic Highway Research Program. The deflection testing must be conducted consistently and with accurately calibrated FWDs. This is a report of the FWDCAL software, which was developed to help ensure that. One aspect of this is the monthly relative calibration of the FWD deflection measurement system. The details are described of how a data set is obtained which can be analyzed to (1) determine a multiplier for each sensor; and statistically partition the measurement errors in the data to the major sources of error, as a check on the acceptability of the calibration data. The FWDCAL software is described which was developed to perform these analyses.
Download or read book Development of Dynamic Analysis Techniques for Falling weight Deflectometer Data written by Allen H. Magnuson and published by . This book was released on 1997 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computer Analysis of Falling weight Deflectometer Data written by Allen H. Magnuson and published by . This book was released on 1988 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: A computer algorithm SCALPOT, consisting of a set of programs and linked files, has been developed that computes responses for physical and geometrical conditions simulating the Dynatest Falling-Weight Deflectometer. Related work on dynamic analysis of layered elastic and viscoelastic media is reviewed. The pavement dynamics problem as measured by the FWD is shown to be a near-field or intermediate-field problem requiring different integration techniques than far-feld problems arising in seismic work. Integration of the formal solution is shown to be best treated by direct numerical integration using a newly developed method of estimating truncation error.
Download or read book Use of Falling Weight Deflectometer Multi load Level Data for Pavement Strength Estimation written by Hee Mun Park and published by . This book was released on 2001 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: falling weight deflectometer, pavement response, fatigue cracking, rutting.
Download or read book The Falling Weight Deflectometer and Spectral Analysis of Surface Waves Test for Characterizing Pavement Moduli written by Kenneth H. Stokoe and published by . This book was released on 1991 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report details the results of tests on newly constructed flexible pavement using a Dynatest 9000 Falling Weight Deflectometer and the Spectral Analysis of Surface Waves test. Additional types of field and laboratory tests were also undertaken and are reported in this study. Taken together, the data and analyses represent a detailed case study of the two non-destructive test methods. When dynamic effects and the demonstrated non-linear behavior of the soil are accounted for, Spectral Analysis of Surface Waves and the Falling Weight Deflectometer provide similar subgrade moduli.
Download or read book Determination by the Falling Weight Deflectometer of the In situ Subgrade Resilient Modulus and Effective Structural Number for I 77 in Virginia written by Khaled A. Galal and published by . This book was released on 2007 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Virginia Department of Transportation (VDOT) manages approximately 27,000 lane-miles of interstate and primary roadways, of which interstate pavements comprise approximately 5,000 lane-miles. These pavements consist of flexible, rigid, and composite pavements. Virginia's pavements are managed using an asset management system (AMS) that incorporates a pavement management system (PMS), which aids VDOT in determining the funding required for various levels of pavement maintenance (i.e., preventive maintenance, rehabilitation, or reconstruction activities). As part of VDOT's AMS (PMS) system, a large portion of the interstate pavement system was visually rated annually to determine a condition index based on load-related and non-load related distresses. Recently, VDOT began using an automated distress collection procedure for this task that incorporates the measurement of pavement condition data such as the international roughness index, rutting in both wheel paths, cracking, and number of patches and potholes. However, there is no current protocol to assess the structural capacity of the pavement on a network level and thus determine the remaining load-carrying capacity (service life) of a pavement structure. Many state departments of transportation use the falling weight deflectometer (FWD) to collect pavement deflection data at the project or network level. The analysis of these data provides the effective roadway resilient modulus, the effective in-situ structural number, the pavement layer moduli, the effective in-situ layer coefficient, or all of these parameters. This process is accomplished through a backcalculation procedure using routines that use the FWD deflection data, known as the deflection basins; the FWD load history; and the pavement layer thicknesses as inputs to this procedure. VDOT currently uses the 1993 AASHTO Guide for Design of Pavement Structures for the design of its new or rehabilitated pavement structures. As VDOT moves to implement the proposed Mechanistic-Empirical Pavement Design Guide (MEPDG), characterizing existing pavement conditions, including the resilient modulus of the subgrade, is necessary to ensure optimum designs. This study collected the in-situ layer conditions, the in-situ structural number, and the in-situ subgrade resilient modulus and deflection data for Virginia's I-77 using FWD network level testing. This testing was found to be a viable tool to classify existing structural network conditions. The information can be used by pavement designers and pavement management engineers to address network needs in terms of rehabilitation strategies and fund management. The study recommends that structural testing on the network level be conducted for all interstate and primary routes in Virginia and used in conjunction with VDOT's AMS. Obtaining such data through traditional destructive testing requires coring and boring operations that incur traffic control, equipment, and personnel costs. To conduct such operations at the network level would cost VDOT approximately $5.06 million annually. The costs for the FWD network level testing used in this study are estimated at $83,200 annually, resulting in an annual cost savings for VDOT of almost $5 million.
