Improvements To Strain Computation And Reliabilty Analysis Of Flexible Pavements In The Mechanistic Empirical Pavement Design Guide
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Improvements To Strain Computation And Reliabilty Analysis Of Flexible Pavements In The Mechanistic Empirical Pavement Design Guide
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Author : Senthilmurugan Thyagarajan
language : en
Publisher:
Release Date : 2009
Improvements To Strain Computation And Reliabilty Analysis Of Flexible Pavements In The Mechanistic Empirical Pavement Design Guide written by Senthilmurugan Thyagarajan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Pavements categories.
Risk Analysis And Reliabilty Improvement Of Mechanistic Empirical Pavement Design
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Author : Danny Xingqiang Xiao
language : en
Publisher:
Release Date : 2012
Risk Analysis And Reliabilty Improvement Of Mechanistic Empirical Pavement Design written by Danny Xingqiang Xiao and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Pavements categories.
Reliability used in the Mechanistic Empirical Pavement Design Guide (MEPDG) is a congregated indicator defined as the probability that each of the key distress types and smoothness will be less than a selected critical level over the design period. For such a complex system as the MEPDG which does not have closed-form design equations, classic reliability methods are not applicable. A robust reliability analysis can rely on Monte Carlo Simulation (MCS). The ultimate goal of this study was to improve the reliability model of the MEPDG using surrogate modeling techniques and Monte Carlo simulation. To achieve this goal, four tasks were accomplished in this research. First, local calibration using 38 pavement sections was completed to reduce the system bias and dispersion of the nationally calibrated MEPDG. Second, uncertainty and risk in the MEPDG were identified using Hierarchical Holographic Modeling (HHM). To determine the critical factors affecting pavement performance, this study applied not only the traditional sensitivity analysis method but also the risk assessment method using the Analytic Hierarchy Process (AHP). Third, response surface models were built to provide a rapid solution of distress prediction for alligator cracking, rutting and smoothness. Fourth, a new reliability model based on Monte Carlo Simulation was proposed. Using surrogate models, 10,000 Monte Carlo simulations were calculated in minutes to develop the output ensemble, on which the predicted distresses at any reliability level were readily available. The method including all data and algorithms was packed in a user friendly software tool named ReliME. Comparison between the AASHTO 1993 Guide, the MEPDG and ReliME was presented in three case studies. It was found that the smoothness model in MEPDG had an extremely high level of variation. The product from this study was a consistent reliability model specific to local conditions, construction practices and specifications. This framework also presented the feasibility of adopting Monte Carlo Simulation for reliability analysis in future mechanistic empirical pavement design software.
Mechanistic Empirical Pavement Design Guide
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Author : American Association of State Highway and Transportation Officials
language : en
Publisher: AASHTO
Release Date : 2008
Mechanistic Empirical Pavement Design Guide written by American Association of State Highway and Transportation Officials and has been published by AASHTO this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Pavements categories.
Mechanistic Empirical Pavement Design Guide Mepdg Method Implemented To Estimate Damage In Flexible And Rigid Pavements
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Author : Tenzin Gusto
language : en
Publisher:
Release Date : 2016
Mechanistic Empirical Pavement Design Guide Mepdg Method Implemented To Estimate Damage In Flexible And Rigid Pavements written by Tenzin Gusto and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
The implementation of the Empirical-Mechanistic Pavement Design Guide (MEPDG) method for flexible and rigid pavements requires numerous input parameters. Most of these parameters can be easily determined while some require best estimates that are usually extracted from available literature. This thesis identifies the most critical input parameters in terms of their effects on the damage of pavements and their influence on the determination of the number of corrective maintenance cycles to be performed during the design life of pavements. It was found that for flexible pavement, change in the average monthly temperature by as little as results in large differences in the number of corrective maintenance cycles. Also, consistently with simple mechanics concepts, pavements on stiffer foundations performed better under the load and hence, required fewer number of the corrective maintenance cycles than those founded on more flexible soils. Also, variations in truck weights affected the outcome in terms of the estimated number of corrective maintenance cycles for flexible pavement. Hence, better estimates of the number of corrective maintenance cycles can be obtained when the analysis was based on larger numbers of truck samples. On the contrary, no significant difference in the final estimation of the number of corrective maintenance cycles was found for rigid pavements even when the average monthly temperatures were increased or decreased by as much as . Moreover, no major difference was observed when a larger sample of trucks was used as input for the analysis. Similarly, change in ambient temperature which is directly related to the differential temperature on the top and the bottom of the slab that may lead to the curling of the slab and faulting, was found not to be critical. Similar to the results obtained for flexible pavements, rigid pavement with stiffer foundation properties performed better in terms of the number of corrective maintenance cycles as they required fewer corrective maintenance cycles.
Development Of A Flexible Pavement Design Procedure Based On The Mechanistic Empirical Pavement Design Guide
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Author : Ali Qays Abdullah
language : en
Publisher:
Release Date : 2012
Development Of A Flexible Pavement Design Procedure Based On The Mechanistic Empirical Pavement Design Guide written by Ali Qays Abdullah and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
This research developed design tables of new flexible pavement structures for New York State Department of Transportation based on the Mechanistic Empirical Design Guide (MEPDG). The design tables were developed using the MEPDG software for Regions 1, 3, and 7 for Upstate part of New York State and for Regions 8, 10, and 11 for the Downstate part of New York State. The MEPDG software was used to run design cases for combinations of: climate conditions, traffic volume, subgrade soil stiffness (Mr) and pavement structures. The conditions that the MEPDG was used to run were: the road structures classified as Principal Arterial Interstate, design 95%reliability level, 15 and 20 year analysis period. Weight in Motion (WIM) data of Region 7 were used for Region 1 and 2, also WIM data of Region 8 were used for Region 10 and 11. Climatic data specifically for each region were used. The NYSDOT's Comprehensive Pavement Design Manual (CPDM) was initially used to obtain pavement design solutions for Region 7 and 8. The granular subbase materials and thicknesses recommended by CPDM were used but only the asphalt layer thicknesses was varied to include several values higher and lower than the thickness recommended by CPDM. The thickness of asphalt binder and surface layers were kept constant. Only the thickness of the base layer was changed. For each design combination, the design case with thinnest asphalt layer for which the predicted distress was less the performance criteria was selected as the design solution. The design solutions for Regions 7 and 8 were assembled in design tables. The examination of the design tables proved that, in general, Region 7 requires thicker pavement structures than Region 8 for same Annual Average Daily Truck Traffic (AADTT) and Resilient Modulus. In the second phase, the MEPDG was used to run for Region 1, 3, 10, 11. The design solutions were tabulated first to produce the design tables for each design case. Since it was expected that the climate changing has no effects on the design solutions for the regions which belong to the same New York State part, the design tables of Region 7 were compared with the design tables of Regions 1 and 3. In addition, the design tables of Region 8 were compared with those obtained for Regions 10 and 11. The comparisons proved that the change in location within the same part of New York State affects the design solution for the same combination of subgrade soil stiffness and truck traffic volume. In the third phase, the design tables for 80% design reliability were produced for each selected region. The design tables which were developed by this study provide flexibility to the designer to design the new flexible pavement structure. The designer should select the subgrade (Mr), AADTT, design life, and the design reliability; then, the design solution could be obtained directly from the tables.
Asphalt Materials Characterization In Support Of Implementation Of The Proposed Mechanistic Empirical Pavement Design Guide
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Author :
language : en
Publisher:
Release Date : 2007
Asphalt Materials Characterization In Support Of Implementation Of The Proposed Mechanistic Empirical Pavement Design Guide written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Pavements, Asphalt concrete categories.
The proposed Mechanistic-Empirical Pavement Design Guide (MEPDG) procedure is an improved methodology for pavement design and evaluation of paving materials. Since this new procedure depends heavily on the characterization of the fundamental engineering properties of paving materials, a thorough material characterization of mixes used in Virginia is needed to use the MEPDG to design new and rehabilitated flexible pavements. The primary objective of this project was to perform a full hot-mix asphalt (HMA) characterization in accordance with the procedure established by the proposed MEPDG to support its implementation in Virginia. This objective was achieved by testing a sample of surface, intermediate, and base mixes. The project examined the dynamic modulus, the main HMA material property required by the MEPDG, as well as creep compliance and tensile strength, which are needed to predict thermal cracking. In addition, resilient modulus tests, which are not required by the MEPDG, were also performed on the different mixes to investigate possible correlations between this test and the dynamic modulus. Loose samples for 11 mixes (4 base, 4 intermediate, and 3 surface mixes) were collected from different plants across Virginia. Representative samples underwent testing for maximum theoretical specific gravity, asphalt content using the ignition oven method, and gradation of the reclaimed aggregate. Specimens for the various tests were then prepared using the Superpave gyratory compactor with a target voids in total mix (VTM) of 7% ± 1% (after coring and/or cutting). The investigation confirmed that the dynamic modulus test is an effective test for determining the mechanical behavior of HMA at different temperatures and loading frequencies. The test results showed that the dynamic modulus is sensitive to the mix constituents (aggregate type, asphalt content, percentage of recycled asphalt pavement, etc.) and that even mixes of the same type (SM-9.5A, IM-19.0A, and BM 25.0) had different measured dynamic modulus values because they had different constituents. The level 2 dynamic modulus prediction equation reasonably estimated the measured dynamic modulus; however, it did not capture some of the differences between the mixes captured by the measured data. Unfortunately, the indirect tension strength and creep tests needed for the low-temperature cracking model did not produce very repeatable results; this could be due to the type of extensometers used for the test. Based on the results of the investigation, it is recommended that the Virginia Department of Transportation use level 1 input data to characterize the dynamic modulus of the HMA for projects of significant impact. The dynamic modulus test is easy to perform and gives a full characterization of the asphalt mixture. Level 2 data (based on the default prediction equation) could be used for smaller projects pending further investigation of the revised prediction equation incorporated in the new MEPDG software/guide. In addition, a sensitivity analysis is recommended to quantify the effect of changing the dynamic modulus on the asphalt pavement design. Since low-temperature cracking is not a widespread problem in Virginia, use of level 2 or 3 indirect tensile creep and strength data is recommended at this stage.
Probabilistic And Reliability Design Procedures For Flexible Airfield Pavements Elastic Layered Method
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Author : Yu T. Chou
language : en
Publisher:
Release Date : 1987
Probabilistic And Reliability Design Procedures For Flexible Airfield Pavements Elastic Layered Method written by Yu T. Chou and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1987 with Pavements, Flexible categories.
A procedure was developed to analyze layered elastic flexible pavement systems in terms of probability and reliability. A computer program RELIBSIA was prepared to carry out the computations. Rosenblueth method, instead of the conventional Taylor series expansion, us used to estimate the expected value and variance of the strains (dependent parameters) based on the input mean values of independent parameters, i.e., aircraft load, layer thicknesses, and material moduli. The relationships between the reliability level and the allowable strain repetition of the designed system which is established with results computed using RELIBISA provide a decision-making tool for engineers to design pavements at desired reliability level. The design can be optimized by selecting thicknesses of the bituminous concrete and the base layers so that the pavement is failed in fatigue cracking and subgrade failure at nearly the same traffic level and the same reliability level. The reliability-strain curves have steeper slopes with the bituminous concrete strain failure criterion than with the subgrade strain failure criterion, indicating that for flexible pavements designed using the Corps of Engineer's failure criteria, the design has a greater degree of uncertainty in preventing subgrade failure than fatigue cracking of the bituminous concrete surface corps. However, this may not be true in real cases because the bituminous concrete failure criteria are determined based on controlled laboratory test data which do not consider the uncertainties existing in the laboratory-to-field correlations.
Mechanistic Empirical Evaluation Of The Mn Road Mainline Flexible Pavement Sections
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Author : Claribel Alvarez
language : en
Publisher:
Release Date : 1998
Mechanistic Empirical Evaluation Of The Mn Road Mainline Flexible Pavement Sections written by Claribel Alvarez and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with Granular materials categories.
This study utilized Illinois DOT (IDOT) mechanistic-empirical (M-E) technology and Mn/ROAD mainline pavement section data and information to verify/refine/modify IDOT M-E analysis and design concepts and procedures for full-depth asphalt concrete (FDAC) and conventional flexible pavements (CFP). The Mn/ROAD mainline flexible pavements include eleven CFP and three FDAC pavement sections. Four different granular materials were used in the conventional flexible pavements. A fine-grained soil subgrade (R-value of about 12) is present throughout the mainline. Laboratory material testing results, field distress measurements, and FWD test data were used to study pavement deflection response and performance (rutting and asphalt concrete fatigue). The study demonstrated that the IDOT M-E analysis and design procedures for FDAC and CFP sections are adequate. The ILLI-PA VE structural model adequately predicts the pavement responses. The use of bi-linear (arithmetic) subgrade model and the "theta" granular material model ILLI-PA VE inputs closely replicate CFP field FWD deflection responses. The effect of granular material quality on CFP deflection response is very limited. The ILLI-PAVE FWD backcalculation algorithms are adequate for estimating the moduli of asphalt concrete and sub grade soils.
Using Fiber Optic Sensor Technology To Measure Strains Under The Asphalt Layer Of A Flexible Pavement Structure
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Author : Stephen R. Sharp
language : en
Publisher:
Release Date : 2006
Using Fiber Optic Sensor Technology To Measure Strains Under The Asphalt Layer Of A Flexible Pavement Structure written by Stephen R. Sharp and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Elastic analysis (Engineering) categories.
In this study, a flexible pavement system was instrumented using fiber-optic strain sensors (FOSS). The purpose of this study was to demonstrate the feasibility of a FOSS installation, monitor the long-term strains under repeated traffic loading, and compare the measured strains with the calculated ones from multi-layer elastic (MLE) analysis. MLE analysis was performed before and after FOSS installation to monitor strains during and after construction. Insitu strains during construction under the hot-mix asphalt (HMA) delivery truck, paver operations, and roller operations were compared to the results of theoretical MLE analysis. In addition, in-situ strains after construction under dump truck and falling weight deflectometer (FWD) loadings at multiple load levels were compared to the results of theoretical and in-situ MLE analysis. The in-situ strain under construction was at least 50 fold that obtained with MLE analysis. The FOSS were sensitive enough to collect strain measurements during construction at very high construction temperatures and moisture conditions. Further, the MLE analysis results were very close to the measured deflection under dump truck and FWD loadings. The results show that MLE analysis can be used to validate and calculate the strains in asphalt pavement sections. Long-term performance monitoring is continuing, and the study will be repeated after FOSS placement in new HMA pavement sections. Understanding the behavior of asphalt pavement under repeated traffic loads can result in an optimized design, thus reducing the rehabilitation costs associated with premature failures or the higher costs associated with conservative asphalt pavement designs. The in-situ strains can be used to calibrate mechanistic-empirical pavement design guide (MEPDG) performance models for local conditions so that measurements can better predict the life of pavement layers and the layers that will need replacement. The installation of FOSS at selected pavement sites that represent the typical pavement designs across the state would allow for the development of accurate statewide mechanistic-empirical performance models, which would lead to more cost-effective pavement rehabilitation decisions.
Local Calibration Of The Mepdg For Flexible Pavement Design
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Author :
language : en
Publisher:
Release Date : 2011
Local Calibration Of The Mepdg For Flexible Pavement Design written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Highway engineering categories.
In an effort to move toward pavement designs that employ mechanistic principles, the AASHTO Joint Task Force on Pavements initiated an effort in 1996 to develop an improved pavement design guide. The project called for the development of a design guide that employs existing state-of-the-practice mechanistic-based models and design procedures. The product of this initiative became available in 2004 in the form of software called the Mechanistic-Empirical Pavement Design Guide (MEPDG). The performance prediction models in the MEPDG were calibrated and validated using performance data measured from hundreds of pavement sections across the United States. However, these nationally calibrated performance models in the MEPDG do not necessarily reflect local materials, local construction practices, and local traffic characteristics. Therefore, in order to produce accurate pavement designs for the State of North Carolina, the MEPDG distress prediction models must be recalibrated using local materials, traffic, and environmental data. The North Carolina Department of Transportation (NCDOT) has decided to adopt the MEPDG for future pavement design work and has awarded a series of research projects to North Carolina State University. The primary objective of this study is to calibrate the MEPDG performance prediction models for local materials and conditions using the data and findings generated from this series of research projects. The work presented in this report focuses on four major topics: (1) the development of a GIS-based methodology to enable the extraction of local subgrade soils data from a national soils database; (2) the rutting and fatigue cracking performance characterization of twelve asphalt mixtures commonly used in North Carolina; (3) the characterization of local North Carolina traffic; and (4) calibration of the flexible pavement distress prediction models in the MEPDG to reflect local materials and conditions.