scholarly journals Effect of variations in layer thickness and resilience modulus on flexible pavement performance

2021 ◽  
Vol 10 (8) ◽  
pp. e42610817466
Author(s):  
Thaís Ferrari Réus ◽  
Heliana Barbosa Fontenele
Keyword(s):  
Layer Thickness ◽  
Design Method ◽  
Flexible Pavement ◽  
Empirical Method ◽  
Performance Criteria ◽  
Pavement Performance ◽  
Layered System ◽  
State Highway ◽  
Pavement Performance Prediction ◽  
Resilience Modulus

A pavement mechanistic-empirical analysis is based on a pre-designed structure checked for required performance criteria. In case the latter are not met, this structure is modified and reprocessed. In this context, analyzing the effect of variations in project parameters on pavement performance prediction subsidizes a better understanding of results provided by computer programs. The objective of this study is to assess the effect of layer thickness and resilience modulus variations on flexible pavement performance. To do so, performance was estimated for the 20th project year through Elastic Layered System Model 5 (ELSYM5) software and American Association of State Highway and Transportation Officials (AASHTO) Mechanistic-Empirical method (ME). Using multiple regression models for result adjustment and through statistical assessments on regression coefficients calculated, it can be concluded that pavement lifespan consumption, predicted by simulations on ELSYM5, is sensitive to variations in coating and subbase thickness and in subgrade resilience modulus. For AASHTO ME method, predicted values for distresses were significantly sensitive to variations in coating, base and subbase thickness, and in base and subgrade resilience modulus. Comparing both approaches, it is concluded that ELSYM5 can be a viable alternative to the application of a ME pavement design method.

Rational Selection of Factors of Safety in Reliability-Based Design of Flexible Pavements in Saudi Arabia

1996 ◽  
Vol 1540 (1) ◽  
pp. 39-47 ◽  
Author(s):  
A. Samy Noureldin ◽  
Essam Sharaf ◽  
Abdulrahim Arafah ◽  
Faisal Al-Sugair
Keyword(s):  
Saudi Arabia ◽  
Performance Prediction ◽  
Flexible Pavement ◽  
Pavement Design ◽  
Pavement Performance ◽  
Design Performance ◽  
Reliability Based Design ◽  
Pavement Engineering ◽  
Pavement Performance Prediction ◽  
Selection Of

Explicit applications of reliability in pavement engineering have been of interest to pavement engineers for the last 10 years. Variabilities in parameters affecting pavement design performance result in variability in pavement performance prediction and thus affect the reliability of how long the pavement will last. Rational quantification of those variabilities is essential for incorporating reliability and selecting the proper factors of safety in the pavement design performance process. The prevailing methodology in Saudi Arabia of quantifying the variability in pavement performance due to the variabilities of the parameters affecting that performance is demonstrated. Factors of safety for flexible pavement design at various reliability levels and based on those prevailing variabilities are presented. These factors of safety are recommended for flexible pavement design in Saudi Arabia.

Partial safety factors for designing and assessing flexible pavement performance

2004 ◽  
Vol 31 (3) ◽  
pp. 397-406 ◽  
Author(s):  
S S Wang ◽  
H P Hong
Keyword(s):  
Safety Factor ◽  
Load Resistance ◽  
Flexible Pavement ◽  
Pavement Performance ◽  
Single Factor ◽  
Safety Factors ◽  
State Highway ◽  
Partial Safety Factor ◽  
Reliability Method ◽  
Partial Safety Factors

In designing and assessing pavement performance, the uncertainty in material properties and geometrical variables of pavement and in traffic and environmental actions should be considered. A single factor is employed to deal with these uncertainties in the current American Association of State Highway and Transportation Officials (AASHTO) guide for design of pavements. However, use of this single factor may not ensure reliability-consistent pavement design and assessment because different random variables that may have different degrees of uncertainty affect the safety and performance of pavement differently. Similar problems associated with structural design have been recognized by code writers and dealt with using partial safety factors or load resistance factors. The present study is focused on evaluating a set of partial safety factors to be used in conjunction with the flexible pavement deterioration model in the Ontario pavement analysis of cost and the model in the AASHTO guide for evaluating the flexible pavement performance or serviceability. Evaluation and probabilistic analyses are carried out using the first-order reliability method and simple simulation technique. The results of the analysis were used to suggest factors that could be used, in a partial safety factor format, for designing or assessing flexible pavement conditions to achieve a specified target safety level.Key words: deterioration, reliability, pavement, serviceability, stochastic process, performance, partial safety factor.

Data Analysis Procedures for Long-Term Pavement Performance Prediction

1996 ◽  
Vol 1524 (1) ◽  
pp. 152-159 ◽  
Author(s):  
H. R. Kerali ◽  
A. J. Lawrance ◽  
K. R. Awad
Keyword(s):  
Data Analysis ◽  
Layer Thickness ◽  
Material Properties ◽  
Pavement Performance ◽  
Model Parameters ◽  
Model Form ◽  
Cubic Model ◽  
Pavement Structures ◽  
Pavement Performance Prediction

The results of 3 years of research aimed at investigating data analysis methods used in the development of pavement performance relationships are reported. The research was part of the U.K. collaborative program linked to the U.S. Strategic Highway Research Program (SHRP), in particular the Long-Term Pavement Performance (LTPP) experiment. The development of pavement performance models usually concludes with the application of regression techniques to determine coefficients for model parameters. It is important to identify the model forms and the engineering or mechanistic principles to be used in the data analyses in the initial stages and then to censor any obvious anomalies in the data. This was applied to data on pavement rutting measured by the Transport Research Laboratory over a 20-year period in the United Kingdom. Engineering knowledge of rutting progression suggests a cubic model form, with the quadratic component representing typical performance in early pavement life. An attempt was made to derive a rutting model that took into account material properties, layer thickness, and aggregate types. The pavement structural number concept was applied as a proxy for pavement strength for the different pavement structures used in the test sites. The results of the analyses confirmed that material properties, layer thickness, and their combined effects influence rutting, but in ways that vary greatly. No simple model form was found to adequately predict rutting for a variety of pavement types, even with general categorical model forms.

Comparison of As-Constructed and As-Designed Flexible Pavement Layer Thicknesses

2003 ◽  
Vol 1853 (1) ◽  
pp. 165-176 ◽  
Author(s):  
Goran Mladenovic ◽  
Y. Jane Jiang ◽  
Olga Selezneva ◽  
Susanne Aref ◽  
Michael Darter
Keyword(s):  
Layer Thickness ◽  
Flexible Pavement ◽  
Target Thickness ◽  
Pavement Performance ◽  
Design Values ◽  
The Mean ◽  
Design Value ◽  
Thickness Deviation ◽  
The Individual ◽  
Distribution Type

Sound pavement design is important for improving pavement performance, but construction is equally critical. Because of variations in pavement construction, the as-constructed pavement layer thickness varies spatially within a pavement section, and the mean constructed pavement layer thickness often deviates from the designed values. The as-constructed pavement layer thicknesses are compared to their design values by using data from the newly constructed flexible pavement sections in the Long-Term Pavement Performance program. First, the distribution type of the mean layer thickness deviation was investigated, and a combined statistical test for skewness and kurtosis showed that the mean thickness deviations may be assumed to be normally distributed for a given layer type and target thickness. Typical thickness deviation summary statistics values were derived to estimate the extent of deviations from the design thicknesses. Second, the analysis showed that elevation thickness data differ from the core examination data. Furthermore, as-constructed layer thickness values were compared to their design values by looking into the percentage of the individual measurements falling into specified ranges from the design values and by using two-sided and one-sided t-tests to compare the mean constructed thicknesses and the design values. The analyses showed that the mean constructed layer thicknesses tend to be above the design value for the thinner layers and below the design value for the thicker layers for the same layer and material type. Results from the study will be useful as inputs for reliability-based design procedures.

scholarly journals A Simplified Mechanistic-Empirical Flexible Pavement Design Method for Moderate to Hot Climate Regions

2021 ◽  
Vol 13 (19) ◽  
pp. 10760
Author(s):  
Ahmed S. El-Ashwah ◽  
Sherif M. El-Badawy ◽  
Alaa R. Gabr
Keyword(s):  
Prediction Accuracy ◽  
Transfer Functions ◽  
Design Method ◽  
Fatigue Cracking ◽  
Flexible Pavement ◽  
Pavement Design ◽  
Pavement Performance ◽  
Climatic Data ◽  
Pavement Structure ◽  
National Cooperative

Flexible pavement structure design is a complex task because of the variability of design input parameters and complex failure mechanisms. Therefore, the aim of this study is to develop and implement a simplified Mechanistic-Empirical (M-E) pavement design method based on the 1993 American Association of State Highway and Transportation Officials (AASHTO), the National Cooperative Highway Research Program (NCHRP) 9-22, and NCHRP 1-37A and 1-40D projects. This simplified methodology is implemented into a computer code and a user-friendly software called “ME-PAVE”. In this methodology, only two equivalent temperatures, as per the NCHRP 9-22 project, are estimated to adjust the dynamic modulus of the asphalt layer(s) for Asphalt Concrete (AC) rutting and AC fatigue cracking prediction instead of using the hourly climatic data, as in the AASHTOWare Pavement ME. In ME-PAVE, the structural responses at critical locations in the pavement structure are determined by a Finite Element Module (FEM), which is verified by a Multi-layer Elastic Analysis (MLEA) program. To ensure that the simplified methodology is practical and accurate, the incorporated transfer functions in the proposed simplified methodology are calibrated based on the Long-Term Pavement Performance (LTPP) data. Based on statistical analyses, the built-in FEM results exhibit very similar trends to those yielded by MLEA, with a coefficient of determination, R2 of 1.0. For all practical purposes, the proposed methodology, despite all simplifications, yields acceptable prediction accuracy with R2 of 0.317 for the rut depth compared to the current practices, NCHRP 1-37A and 1-40D (R2 = 0.399 and 0.577, respectively); while the prediction accuracy for fatigue cracking with R2 of 0.382 is comparable to the NCHRP 1-40D with R2 of 0.275. Nonetheless, the standard error for both distresses is in good agreement based on the investigated data and the developed methodology. Finally, the conducted sensitivity analysis demonstrate that the proposed methodology produces rational pavement performance.

Use of Long-Term Pavement Performance Data to Develop Traffic Defaults in Support of Mechanistic-Empirical Pavement Design Procedures

2003 ◽  
Vol 1855 (1) ◽  
pp. 176-182 ◽  
Author(s):  
Weng On Tam ◽  
Harold Von Quintus
Keyword(s):  
Pavement Design ◽  
Vehicle Classification ◽  
Pavement Performance ◽  
Traffic Data ◽  
Design Procedures ◽  
Load Spectra ◽  
State Highway ◽  
Pavement Structures ◽  
Empirical Design

Traffic data are a key element for the design and analysis of pavement structures. Automatic vehicle-classification and weigh-in-motion (WIM) data are collected by most state highway agencies for various purposes that include pavement design. Equivalent single-axle loads have had widespread use for pavement design. However, procedures being developed under NCHRP require the use of axle-load spectra. The Long-Term Pavement Performance database contains a wealth of traffic data and was selected to develop traffic defaults in support of NCHRP 1-37A as well as other mechanistic-empirical design procedures. Automated vehicle-classification data were used to develop defaults that account for the distribution of truck volumes by class. Analyses also were conducted to determine direction and lane-distribution factors. WIM data were used to develop defaults to account for the axle-weight distributions and number of axles per vehicle for each truck type. The results of these analyses led to the establishment of traffic defaults for use in mechanistic-empirical design procedures.

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