Developing a tool to estimate the traffic loading frequency equivalent to be inserted into the flexible pavement design method

Abstract

In the design of flexible pavements subjected to dynamic vehicular loading, it is crucial to accurately model the behaviour of asphalt layers. To achieve this, it is necessary to transfer the traffic loading from the time domain, in which the loading applies on top of the surface through time, to the frequency domain, which is used to simulate the bituminous material behaviour in the laboratory. In this context, an iterative/conversion tool is developed to estimate the equivalent angular frequency for traffic loading. The tool is built by analyzing the instantaneous deformation recorded by strain gauges installed at the bottom of the asphalt layer of the ULAVAL paved system. The analysis begins by calculating the stiffness of the asphalt layer in each testing temperature based on the 2S2P1D model. Then, the effective loading signals are extracted through the estimation of effective loading time using the Odemark method. The isolated signals are then transformed into the frequency domain by Fourier analysis in Microsoft Excel to obtain the equivalent frequency for each temperature as the peak frequency in the converted signals. To validate the results, the calculated equivalent frequencies are inputted into the 2S2P1D calculation as the initial loading frequency and the process is repeated until there are no differences between the initial loading frequency and the equivalent frequency in the result. By obtaining the equivalent frequency for the traffic loading parameter, the behaviour of the asphalt layers can be modelled more accurately, leading to a more precise design of flexible pavements under dynamic vehicular loading. The proposed methodology in this study allows for the estimation of equivalent frequency for various pavement conditions and loading speeds. It provides a reliable and efficient tool for engineers to estimate the effective loading time and equivalent frequency of traffic loading, which are crucial parameters for designing flexible pavements with improved accuracy.

Date	14 Aug 2023
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Alan Carter (Supervisor) & Michel Vaillancourt (Co-supervisor)