Sensitivity Analysis of Rigid Pavement Design Inputs Using Mechanistic-empirical Pavement Design Guide

Sensitivity Analysis of Rigid Pavement Design Inputs Using Mechanistic-empirical Pavement Design Guide
Author: Alper Guclu
Publisher:
Total Pages: 228
Release: 2005
Genre:
ISBN:

Pavement design procedures, available in the literature, do not fully take advantage of mechanistic concepts, which make them heavily rely on empirical approaches. Because of the heavy dependence on empirical procedures, the existing design methodologies do not capture the actual behavior of Portland cement concrete (PCC) pavements. However, reliance on empirical solutions can be reduced by introducing mechanistic-empirical methods, which is now adopted in the newly released mechanistic-empirical pavement design guide (MEPDG). This new design procedure incorporates a wide range of input parameters associated with the mechanics of rigid pavements. To compare the sensitivity of these various input parameters on the performance of concrete pavements, two jointed plain concrete pavement (JPCP) sites were selected in Iowa. These two sections are also part of the Long Term Pavement Performance (LTPP) program where a long history of pavement performance data exists. Data obtained from the Iowa Department of Transportation (Iowa DOT) Pavement Management Information System (PMIS) and LTPP database were used to form two standard pavement sections for the comprehensive sensitivity analyses. The sensitivity analyses were conducted using the MEPDG software to study the effects of design input parameters on pavement performance of faulting, transverse cracking, and smoothness. Based on the sensitivity results, ranking of the rigid pavement input parameters were established and categorized from most sensitive to insensitive to help pavement design engineers to identify the level of importance of each input parameter. The curl/warp effective temperature difference (built-in curling and warping of the slabs) and PCC thermal properties are found to be the most sensitive input parameters. Based on the comprehensive sensitivity analyses, the idea of developing an expert system was introduced to help the pavement design engineers identify the input parameters that they can modify to satisfy the predetermined pavement performance criteria. Predicted pavement distresses using the MEPDG software for the two Iowa rigid pavement sites were compared against the measured pavement distresses obtained from the Iowa DOT's PMIS and comparison results are discussed in this study.

Guide for the Local Calibration of the Mechanistic-empirical Pavement Design Guide

Guide for the Local Calibration of the Mechanistic-empirical Pavement Design Guide
Author:
Publisher: AASHTO
Total Pages: 202
Release: 2010
Genre: Technology & Engineering
ISBN: 1560514493

This guide provides guidance to calibrate the Mechanistic-Empirical Pavement Design Guide (MEPDG) software to local conditions, policies, and materials. It provides the highway community with a state-of-the-practice tool for the design of new and rehabilitated pavement structures, based on mechanistic-empirical (M-E) principles. The design procedure calculates pavement responses (stresses, strains, and deflections) and uses those responses to compute incremental damage over time. The procedure empirically relates the cumulative damage to observed pavement distresses.

Flexible Pavement Design

Flexible Pavement Design
Author: Ashraf Ayman Aguib
Publisher:
Total Pages: 268
Release: 2014
Genre: Maintainability (Engineering)
ISBN:

Abstract: The new Mechanistic-Empirical Pavement Design Guide (MEPDG) provides a state- of-the-art and practice pavement design procedure that eradicates the AASHTO 1993 empirical design procedure deficiencies. Huge advancements with respect to traffic input, material characterization and environmental impact are incorporated in the MEPDG. The AASHTO 1993 design procedure is based on empirical equations derived from the AASHO Road Test conducted in the late 1950's in a test track in Ottawa, Illinois. The test provided very useful information for the design of pavement at that time. However, with the present advancement in materials and dramatic increase in traffic volumes, this empirical design procedure started to show massive drawbacks. The MEPDG is a more comprehensive design procedure that incorporates sophisticated models for pavement response calculation, material properties variations with respect to environmental conditions and pavement performance predictions. The mechanistic part of the design procedure is the pavement response calculation and the empirical part of the method is the pavement performance prediction. Incorporating these models allows the MEPDG of producing pavement design sections that are cost-effective and perform better than those designed using the AASHTO 1993 design procedure for a given life span. With the initial introduction of the MEPDG in 2004, almost every State Highway Agency (SHA) in the United States and several road authorities around the world exerted efforts to understand and plan to implement the MEPDG according to their own local conditions. It was hence found necessary to explore the new design procedure according to Egyptian local conditions. The objectives of the research is to prepare a body of accurate and readily usable environmental data for Egypt for MEPDG input, compare the effectiveness of both design methods and assess the sensitivity of MEPDG predicted performance with respect to variations in inputs. Weather data files for major Egyptian cities were extracted from available data sources and prepared for direct input in the MEPDG. The preparation of data was done using a computer application especially developed in this research program to comprehensively and rationally complete this task. A comparative study was then done between the two design methods. Five pavement sections were designed using the AASHTO 1993 design procedure and then evaluated using the MEPDG for three traffic levels. These five sections were chosen to best represent the majority of Egypt. A sensitivity analysis was then conducted to investigate the predicted behavior of fatigue cracking and rutting with respect to variations in environmental conditions, traffic levels, AC layer thickness and properties, granular base (GB) layer thickness and subgrade strength. Comparing both design methods revealed that pavements designed under the AASHTO 1993 do not perform equally at the end of their design life. Terminal Present Serviceability Index (PSI) values are different for different traffic levels and locations. Predicted fatigue cracking and rutting showed a similar trend to terminal PSI values. The AASHTO 1993 was also found to over-estimate pavement layers thicknesses. Predicted fatigue cracking showed high sensitivity to design inputs under the scope of the study. Environmental conditions and traffic loading were also found to be the most influential input parameters on the selected pavement performance indices. Unexpected results for predicted rutting lead to further investigation and MEDPG rutting prediction model was evaluated with respect to an Egyptian rutting prediction model. Rutting prediction model adopted by MEPDG produced lower values for permanent strain compare to the Egyptian rutting model and further calibration for the MEPDG rutting prediction model was found necessary.