The aim of this paper is to present a thermoviscoelastic multilayer model using the huetsayegh behaviour. Road structures and materials in low volume roads in cold climate areas generally follow visco elastic or visco elasticplastic behaviour rather than elastic behaviour. The visco elastic behaviour was described with rheological huetsayegh model and pavement responses estimation was done using mnlayer and viscoroute2 software. Called rigid since pccs high modulus of elasticity does not allow them to flex appreciably. Analyticalempirical pavement evaluation using the falling. The french design method uses the burmister multilayer elastic model. Mechanistic design procedure are based on the assumption that a pavement can be modeled as multi layered elastic or visco elastic structure on an elastic or visco elastic foundation. Considerable deflection data are analyzed during the study using different models. Pcase software is considered public information and is therefore free to all users. Bouldin a new method of analysis for mechanistic pavement design has been developed based on improved malerial characteristics. Burmister extended boussinesqs theory from a single layer to a multilayer elastic model 4.
Lecture notes ct 4860 structural pavement design design of. Coefficient of drainage cd or mi cd is the coefficient of drainage for rigid pavement design used to account for improved or decreased quality of drainage. Prediction of viscoelastic pavement responses under moving. A finite element based backcalculation program for flexible. Viscoelastic response modelling of a pavement under moving.
Viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Fatigue and rutting strain analysis of flexible pavements. An example of design without soil strength test is by using hrb soil classification system, in which soils are grouped from a1 to a7 and a group index is. The model is implemented in generalpurpose febased software, abaqus. Influence of asphalt viscoelastic properties on flexible. Mar 29, 20 in this study, predictions of fullscale micromechanical mm finite element fe models, developed from xray computed tomography images of asphalt concrete samples that were sawn from the accelerated pavement test sections, were used to evaluate the accuracy of layered elastic theory let models that are used in pavement design today. For multilayered systems, several software programs have been developed for linear elastic, nonlinear, and visco elastic analysis using finite element method, which give accurate results. The theory of stresses and displacements in layered systems and. Huetsayegh 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. The aashto 1993 flexible pavement design emphasizes on the particulars involved in designing the pavements meticulously so that they can bear the traffic load and the impact of the temperature variation at the same time.
Software for pavement analysis and design pavement research center of excellence department of civil and environmental engineering michigan state university. Other topics covered in the course include connection design and construction, fatigue analysis, deck design and bearing design. It is however important to understand the role of the elastic modulus in determining the bearing capacity and resistance to permanent deformation in the different parts of the. In this research, the linear visco elastic lve behavior of the existing asphalt mixes is analyzed. Viscoelastic approach enhanced analysis of falling. A field observation for evaluation of pavement surface conditions of roads network, showed that, rutting and fatigue cracking are considered.
Using schaperys quasielastic theory, the viscoelastic response at time t to a unit. Theory of stresses and displacements in twolayer viscoelastic systems. Investigation of layered elastic theory prediction. The french pavement design method consists in a pavement mechanistic analysis based on the. The procedure is based on the multilayered elastic theory mlet and the elasticviscoelastic correspondence principle using a numerical inverse laplace transform. Stresses and strains in road structures roadex network.
Fast layered elastic response program for analysis of flexible pavement structures. The pavement strain responses decreased as the speed increased due to viscoelastic behavior of asphalt layer. Pdf viscoelastic modeling for asphalt pavements software. Read investigation of layered elastic theory prediction accuracy for asphalt concrete pavement design using micromechanical viscoelastic finite element modeling, materials and structures on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Viscous materials, like water, resist shear flow and strain linearly with time when a stress is applied. The french pavement design method consists in a pavement mechanistic analysis. Viscoelastic analysis of flexible pavements and its. It is well known that an asphalt mixture is a viscoelastic material, so its response. Based on small strain theory, the straindisplacement relationship can be. The model was later used to develop the 3dmove pavement analysis software. A layered elastic model can compute stresses, strains and deflections at any point in a pavement structure resulting from the application of a surface load. The rhea software is a rapid userfriendly method to analyze data from frequency sweep, relaxation or creep experiments to determine a wide range of visco elastic properties that are used in specifications.
Pdf influence of asphalt viscoelastic properties on. Viscoelastic modelling for asphalt pavements software. Visco elastic modelling for asphalt pavements software viscoroute. South african mechanistic design method samdm hechter. Rutting deformations analysis for asphalt pavement base on. Some pavement design procedures recommend that the subgrade moduli determined from fwd tests, based on linear elastic theory, be divided by a factor of 2 to 3. A comparison of the direct layered viscoelastic responses with approximate solutions based on the elastic collocation method was also carried out. The new program is called faa rigid and flexible iterative elastic layered design, but is known by its acronym, faarfield. Prediction of viscoelastic pavement responses under moving load.
The increase in modulus with distance from the load may be caused by other phenomena, such as a gradually. Elastic materials strain when stretched and immediately return to their original state once the stress is removed. Analytical solutions of viscoelastic pavement responses vary with different. Bouldin a new method of analysis for mechanistic pavement design has been developed based on improved material characteristics, which more accurately reflects fatigue cracking and permanent deformation perfor mance. Viscoelastic response modelling of a pavement under moving load. The increased rutting or decreased fatigue life of the flexible pavements may be attributed to the shortcomings of the application. It will be assumed that the materials are isotropic, homogeneous and linear elastic. Surface pavement deflections and strains at the bottom of asphalt layers were computed and analyzed. The top layer bears more stresses than the lower ones flexible pavement design. The multilayered elastic theory is widely used to determine the tensile strain for. Ernian pan who, as the program advisor and committee director. Results of this analysis indicated that the elastic theory grossly underpredicts pavement responses to vehicular loading at intermediate and high temperatures. Pavement design using empirical or layered elastic methodology for. Layered elastic models assume that each pavement structural layer is homogeneous, isotropic, and linearly elastic.
The flexible pavement design is made in such a way that the structure basically deflects under load. Thus based on correspondence principle in the theory of linear viscoelaticity we can replace e. Viscoelastic modeling for asphalt pavements software viscoroute. The program is called veroad, viscoelastic road analysis delft. Huetsayegh model 1963 gives a set of constitutive equations of a viscoelastic material which accounts well for the behaviour of asphalt pavement layers, especially regarding thermal effects. Design pamphlet for the backcalculation of insupport of. Pavement analysis and design software pads based on the south african mechanisticempirical design method h l theyse and m muthen transportek csir, p o box 395, pretoria, 0001 introduction the trh4 structural design of flexible pavements for interurban and rural roads guideline document 1 was revised during the period 1994 to1995. Some applications of the elastic theory approach to the.
Analysis on the fatigue life of asphalt pavement under. Pavement design resources flexible pavements of ohio. Pavement design tries to prevent the major distress such as permanent deformation rutting and fatigue cracking. Ijsii a simplified viscoelastic model for the asphalt concrete surface course, solutions for typical loading problems are given. On account of the viscoelastic ac, the theory of linear viscoelasticity is reformulated briefly from a. This report presents the results of a literature survey into design methods for asphaltic pavements, discussing. The pavement structure was loaded by the typical standard 50 kn single wheel moving at a speed of 60 kmh. Results of this analysis indicated that the elastic theory grossly underpredicts pavement responses to vehicular loading at. Calculation of the elastic moduli of a two layer pavement system from measured surface deflections by frank h. Viscoelastic analysis of hot mix asphalt pavement structures g.
Calculation of the elastic moduli by research report number 1236. The roadex project does not take any responsibility for its use in real design projects. Nevertheless, asphalt mixes are not simple materials. An empirical analysis of flexible pavement design can be done with or with out a soil strength test. Other pavement design resources asphalt paving alliances construction checklist for parking lots this checklist is designed to help the onsite inspector or owners representative identify key aspects of parking lot construction and best practices known to produce a quality pavement project.
After a 10year research and development effort, the federal aviation administration faa is set to debut a new software package for airport pavement thickness design. Viscoelastic modelling for asphalt pavements software viscoroute. Elastic modulus in this paper should be understood to be an apparent modulus or effective stiffness. The french pavement design method consists of a pavement mechanistic analysis based on the burmister multilayer elastic model 1943 lcpc software alize 1982. Comparison of elastic and viscoelastic analysis of asphalt. Analytical modelling of visco elastic behaviour of hotmix asphalt j komba, j w maina, j k anochieboateng, and j oconnell csir built environment, building 2c, p o box 395, pretoria, 0001, south africa tel.
The publications on dma are full of complex ideas and daunting math that do not typically attract the interest of designers and engineers tasked with developing products, even though the underpinnings of viscoelastic theory govern everything that happens to our plastic products once they are in use. After that, the boussinesq model has been improved by the work of burmister 1945. The analysis reviled static and dynamic load influence on pavement structure based on elastic and visco elastic properties of asphalt layers. Although the mechanistic empirical pavement design guide mepdg 2004. In addition, the elastic fe model could not simulate permanent deformation or delayed recovery, a known characteristic of hma materials.
By means of the fast fourier transform method, the equations of the model are solved in the coordinate system of the moving load. The study results indicate that asphalt pavement responses under moving load can be calculated using the proposed 2. The analysis also enables the pavement designer to predict. To help move the implementation forward, fhwa intends to provide significant support for these efforts. An example of design without soil strength test is by using hrb soil classification system, in which soils are grouped from a1 to a7 and a group index is added to differentiate soils within each group. The roadex pavement stress and strain calculation demo. Viscoelastic theory article about viscoelastic theory by. Assumption natural soil subgrade aggregate subbase course aggregate base courseasphalt concrete 11. Comparison of isotropic and crossanisotropic analysis of. Influence of asphalt visco elastic properties on flexible pavement performance article pdf available in the baltic journal of road and bridge engineering 114. Flexible pavement mechanistic models pavement interactive. Pavement design with examples complete data civildigital. A finite element based backcalculation program for. Mar 29, 20 read investigation of layered elastic theory prediction accuracy for asphalt concrete pavement design using micromechanical viscoelastic finite element modeling, materials and structures on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
All this explains why the current design methods are classified as mechanistic empirical. Investigation of layered elastic theory prediction accuracy. Assumption natural soil subgrade aggregate subbase course aggregate base. Viscoelastic modeling and field validation of flexible pavements. The principles of the derivation apply equally to conventional linear elastic programs. It would be more appropriate to consider the nonlinearity. In this study, predictions of fullscale micromechanical mm finite element fe models, developed from xray computed tomography images of asphalt concrete samples that were sawn from the accelerated pavement test sections, were used to evaluate the accuracy of layered elastic theory let models that are used in pavement design today. Calculations were conducted using veroad visco elastic road analysis delft program. The structure is designed in such a way that each layer comprising of materials receives load. Base on visco elastoplastic theory, using laplace transformation the asphalt pavement parameters of viscoelasticity model and visco elastoplastic model are converted into parameters of prony series, the rutting deformations of asphalt pavement are analyzed by using ansys, the influence of load, material temperature and loading cycles are considered. To fully utilize each pavement material in an economic design, a pavement should generally have reasonably balanced design between the rutting and fatigue modes of distress. Design pamphlet for the backcalculation of insupport of the.
Apr 19, 2016 mechanistic design procedure are based on the assumption that a pavement can be modeled as multi layered elastic or visco elastic structure on an elastic or visco elastic foundation. For this reason, multiple layers are preferred to a single thick layer in the construction of flexible pavements. The theory of viscoelasticity is concerned with the behavior of materials which exhibit timedependent stressstrain characteristics. Their mechanical properties are the principal cause of its visco elastic behavior. The origin of layered elastic theory is credited to v. Pavement analysis and design software pads based on the. The stresses and strains for the demo were precalculated using bisar software based on linear elastic theory. To study the fatigue life of asphalt pavement under traffic loads, a 3d finite element analysis fea visioelastic road model was established on the layered theory with ansys software. A sensitivity analysis performed on various design parameters indicated that the.
In these lecture notes we will concentrate on the use of linear elastic multi layer theory for the calculation of stresses and strains in pavement structures. Among of the viscoelastic programs applied to pavement analysis, the program. Since the early 1960s, pavement engineers have gone from empirical to mechanistic. To study the fatigue life of asphalt pavement under traffic loads, a 3d finite element analysis fea visio elastic road model was established on the layered theory with ansys software. Slide 5 samdm revision overall objective to develop a design method that is. Thank you for obtaining a copy of the rhea software. In mechanistic design, adequate control of pavement layer thickness as well as material quality are ensured based on theoretical stress, strain or deflection analysis. I ran kenpave software for the linear elastic behavior no visco elastic and nonlinear case. Model, boyce model, pappin model, elhannani model and linear elastic, while for the subgrade nonlinear elastic and linear elastic are used. Moore research report number 1236 a system analysis of pavement design and research implementation research study number 1869123 conducted in cooperation with the. Flexible pavement, as the name suggests, is composed of a number of layers of materials.
Elastic theory methods assume that the pavement has adequate strength for the wheel load to be carried, and that the pavement surface after deflecting as. Burmister introduced the use of the multilayer elastic theory to analyse pavement structures. Calculation of the elastic moduli by research report. Bituminous testing spreadsheet version 2, xlsm 400 kb if you have data in a version 1 spreadsheet and would like it updated to version 2, contact bruce. Viscoelastic analysis of hot mix asphalt pavement structures. This course introduces the fundamentals of steel bridge theory, analysis, and design, including single and continuous span bridge structures. Therefore the complete viscoelastic behaviour of each asphalt pavement layers has to be taken into account. Viscoelastic nonlinear multilayered model for asphalt pavements. Knowledge of the e master curve of an inservice pavement using fwd data can lead to a more accurate estimation of its remaining life and rehabilitation design. The procedure is based on the multilayered elastic theory mlet and the elasticviscoelastic.