01626229

Component

The moduli of different materials in a pavement structure play a fundamental role in the resulting distribution of stresses, strains and deflections. For unbound materials, the resilient modulus (M sub r) is used as the design elastic modulus. It is well known that M sub r is stress-dependent. For some materials, it may also be affected significantly by environmental conditions. This creates a problem for designers, particularly for layers with significant changes in the stress distribution, since no single M sub r value can be used to predict accurately all the critical strains. This paper discusses challenges faced for selecting input M sub r values when calibrating the AASHTOWare Pavement ME Design program for Hawaii. Using non-linear elastic finite element analysis (FEA), it shows the M sub r variation with depth and distance from the center of the load for several combinations of unbound materials M sub r parameters, Hot Mix Asphalt (HMA) layer modulus, and load levels. The results illustrate the substantial variations in moduli within an unbound layer that may be induced, both vertically and horizontally for a single load with varying HMA moduli or for a single HMA modulus with varying loads, which makes the selection of a single input M sub r value producing equivalent distributions of stresses and strains virtually impossible. It is also found that using the recommended values in the Mechanistic-Empirical Pavement Design Guide (MEPDG) manual of practice may result in very high predicted M sub r values for thick pavement sections. Thus, the option of allowing the program to modify the input M sub r values based on predicted environmental changes should be used with caution.

This paper was sponsored by TRB committee AFP60 Standing Committee on Engineering Behavior of Unsaturated Geomaterials.

01618707

17-06009

English

18p

2017

Transportation Research Board 96th Annual Meeting

Digital/other

Figures; References

Calibration; Mechanistic-empirical pavement design; Modulus of resilience

AASHTOWare (Software); Mechanistic-Empirical Pavement Design Guide

Hawaii

Design; Highways; Pavements

Transportation Research Board Annual Meeting 2017 Paper #17-06009

TRIS, TRB, ATRI

Dec 8 2016 12:25PM