Prediction of the behaviour of a flexible pavement using finite element analysis with non-linear elastic and viscoelastic models (original) (raw)
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Modelling granular pavement materials has a significant role in the pavement design procedure. Modelling can be through an experimental or numerical approach to predict the granular behaviour during cyclic loading. The current design process in Australia is based on linear elastic analysis of layers. The analysis is performed through a well-known program CIRCLY which is applied to model bound pavement material behaviour. The KENLAYER is one of the common pavement software models used for pavement design in the United States which performs non-linear analysis for granular materials. Alternatively, a general Finite Element program such as ABAQUS can be used to model the complicated behaviour of multilayer granular materials. This study is to compare results of numerical modelling with these three programs on two sample pavement models.
Non-linear finite element analysis of flexible pavements
Advances in Engineering Software, 2003
A research study is being undertaken to incorporate the realistic material properties of the pavement layers and the moving traffic load, in the analysis of flexible pavements, using the finite element theory. As a preliminary step taken herein in this direction, a pavement structure where field measurements have been carried out when subjected to a cyclic loading, is selected and modelled as a finite element model. The analysis is being carried out using the finite element computer package ABAQUS/STANDARD, when this pavement model is subjected to static and cyclic loading while considering the linear and non-linear material properties of the pavement layers. The results indicate that displacements under cyclic loading when non-linear materials are present, are the closest to field measured deflections. q
Modelling of Pavement Materials –Numerical and Experimental Aspects
Results of an extensive experimental and numerical research project on the response of Asphalt Concrete (AC) are presented. In the projects a material model for AC is being developed and implemented in the Finite Elements package CAPA-3D. Also, the test set-ups, instrumentation and test procedures necessary to characterise the material and determine the model parameters were developed. In an early stage of the project it was recognised that failure in tension and compression followed a different mechanism and needed to be described separately in order to capture the response to alternating loads. From the results of uniaxial tension tests it became apparent that also in tension a pronounced non-linearity occurred prior to the peak load. The adaptations necessary to incorporate this in the model are presented in this paper. The response predicted by the model relations is compared to that observed in laboratory tests to validate the model relations and it can be seen that the observed behaviour is described quite well by the model.
Assessment of Linear and Non-Linear Analyses of Flexible Pavement
International Conference on Aerospace Sciences and Aviation Technology, 1999
Two computer programs were reviewed and evaluated, one for linear an alysis (LA) and the other for non-linear analysis (NLA), to identify the most appropOate analysis type for flexible pavement structural analysis. The programs were three-dimensional (3-D) finite element (FE) programs called SAP90 and ANSYS5.3. The comparison items were the maximum surface deflection, the maximum' vertical compressive strain at the top of the subgrade and the maximum horizontal tensile strain at the bottom of the asphalt concrete (AC)'lkOr, which are the most commonly used criteria for pavement design. In addition to these items, maximum tensile stress in AC layer and vertical stress distribution alort the pavement depth were used as the basis for comparison. Three load conditions include horizontal forces (HF) were applied to the flexible pavement models. Non-linear analysis was found to be more realistic for flexible pavement analysis. It satisfied the surface boundary condition and gave more acceptable results when studying shoving and vertical stress distribution under loading center.
NonPAS: A Program for Nonlinear Analysis of Flexible Pavements
2015
Normal 0 false false false EN-US X-NONE FA MicrosoftInternetExplorer4 The primary step in design of a pavement using Mechanistic-Empirical (M-E) method is the analysis of pavement and calculation of the critical responses of pavement under various loadings. This confirms the need for developing pavement analysis software as an analytical base of the M-E method. To this end, NonPAS program has been developed for linear and nonlinear analysis of flexible pavements. Developed program allows nonlinear analysis of flexible pavements using five nonlinear models, including K-θ, Uzan, Uzan-Witczak, MEPDG 2002 and Bilinear models. Nonlinear Analysis of flexible pavements by utilizing these constitutive models provides a more accurate modeling of granular material behavior. Developed program can be used to analyze a pavement system consists of maximum of 10 layers, which is subjected to a maximum of six circular loads. Developed program allows for calculating the responses at 400 different po...
Analysis of Response of Flexible Pavements Using Finite Element Method
2005
The characteristic response of flexible pavements under traffic load depict a delayed lateral strain relaxation (Viscoelasticity), a phenomenon that may be more accurately and expeditiously analysed using finite element (FE) viscoelastic response models. In this study a flexible pavement was modelled using ANSYS/ED finite element software suite. The pavement model was subjected to cyclic loading that simulated three levels of truck loads on 10R20 tyres at four tyre inflation pressures (viz. 350,490,630 and 770 kPa). The modelled results were in good agreement with the measured in-situ full-scale test data. Therefore, for known pavement material characteristics and tyre-pavement contact regime, finite element method could be used to efficiently estimate the fatigue life of flexible pavement with thin bituminous surfacing layers. * Corresponding author. Tel: +35318851194; Fax: +353-1-8851001 Email address: rachel.mulungye@itb.ie Introduction Characteristic response of in-situ bitumino...
2011
Resilient modulus is an important input for computation of the structural response of pavements in Mechanistic -Empirical Methods. It has a significant effect on computed pavement responses and predicted pavement performance. The main objective of the research study that is introduced here is to develop a material model subroutine applicable to Finite Element program to simulate the nonlinear behavior of unbound granular materials, and evaluate the influence of using different constitutive models for characterization of unbound granular materials on critical responses of Flexible pavements. These constitutive models include Linear Elastic, Uzan and Universal models. For this purpose, three different pavement sections are assumed and FE models for these sections were verified by comparing elastic responses with KENLAYER Program. A granular base with known material constants for these three models was selected and sections were analyzed using different constitutive models. The results...
This paper explains the importance of using a nonlinear anisotropic three-dimensional (3D) finite-element (FE) pavement model to simulate the granular base layer and predict viscoelastic pavement responses under moving vehicular loading. The FE model was built using the general-purpose FE software ABAQUS, and a user material subroutine was developed to implement the constitutive model of granular material using a modified Newton-Raphson approach with secant stiffness. The FE model utilizes implicit dynamic analysis and simulates the vehicular loading as a moving load with 3D contact stresses at the tire-pavement interface. The analysis results indicate that it is important to consider the viscoelastic nature of the asphalt layer and the moving load for accurately capturing the nonlinear granular base modulus in the mechanistic pavement model. The modulus distribution in the granular base layer is affected not only by wheel load and pavement structure (such as asphalt layer thickness and subgrade support) but also by temperature and vehicle speed because of the viscoelastic behavior of the asphalt surface layer. Excluding the cross-anisotropic stress-dependent behavior of the granular base layer could cause significant error in predicting fatigue cracking and rutting potential in thin asphalt pavements. In addition, the model results captured the trends of field measurements at different loading and temperature conditions.
Visco-elastic modelling for asphalt pavements : Software ViscoRoute
HAL (Le Centre pour la Communication Scientifique Directe), 2006
Huet-Sayegh model (1963) gives a set of constitutive equations of a visco-elastic material which accounts well for the behaviour of asphalt pavement layers, especially regarding thermal effects. This model allows rather good predictions of experimental data. The French pavement design method consists in a pavement mechanistic analysis based on the Burmister multilayer elastic model (1943)-LCPC software ALIZE (1982)-. In that model, the Huet-Sayegh behaviour is taken into account with its equivalent elastic modulus at the 15°C French average temperature and a 10 Hz frequency. That frequency value is assumed to be equivalent to the standard 72 km/h French vehicle speed. Such semi-analytical calculations provide relatively good stress and strain fields for heavy traffic pavements but it is less satisfactory for flexible pavements with low traffic, for high temperature gradients and for the analysis of damages under slow heavy loads. Therefore the complete visco-elastic behaviour of each asphalt pavement layers has to be taken into account. The aim of this paper is to present a thermo-visco-elastic multi-layer model using the Huet-Sayegh behaviour. By means of the Fast Fourier transform method, the equations of the model are solved in the coordinate system of the moving load. Results are successfully compared with an analytical solution, finite element results and accelerated pavement testing data. A software called ViscoRoute (i.e. ViscoRoad) based on this modelling has been developed. The second part of this work deals with the relevance of the assumption on the time-frequency equivalence of the French design method.
Viscoelastic Modeling and Field Validation of Flexible Pavements
The objective of this study was to characterize hot-mix asphalt ͑HMA͒ viscoelastic properties at intermediate and high temperatures and to incorporate laboratory-determined parameters into a three-dimensional finite element ͑FE͒ model to accurately simulate pavement responses to vehicular loading at different temperatures and speeds. Results of the developed FE model were compared against field-measured pavement responses from the Virginia Smart Road. Results of this analysis indicated that the elastic theory grossly underpredicts pavement responses to vehicular loading at intermediate and high temperatures. In addition, the elastic FE model could not simulate permanent deformation or delayed recovery, a known characteristic of HMA materials. In contrast, results of the FE viscoelastic model were in better agreement with field measurements. In this case, the average error in the prediction was less than 15%. The FE model successfully simulated retardation of the response in the transverse direction and rapid relaxation of HMA in the longitudinal direction. Moreover, the developed model allowed predicting primary rutting damage at the surface and its partial recovery after load application.