Structural Responses of Flexible Pavement Subjected to Different Axle Group Loads (original) (raw)
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Analysis of flexible pavement structural responses under the falling weight deflectometer
2019
This study investigated the structural responses of flexible pavement under the falling weight deflectometer (FWD). The finite-element analysis (FEA), the multi-layer linear-elastic analysis (LEA), and the elastic solution were performed to examine flexible pavement responses to a series of FWD measurement. The FWD applied a uniform circular load of approximately 756 kPa through a 300-mm diameter loading plate. The corresponding surface deflections were measured using a linear array of nine geophones. An axisymmetric finite-element model was developed to predict pavement responses and compared with the LEA and the closed-form solution based on the elastic theory. Comparison results indicated that the surface defections determined from the FEA and LEA were close to those measured by the FWD, while the elastic solution tended to underestimate the surface deflections. Most structural responses determined from both FEA and LEA were comparable for a given modulus of elasticity.
Structural Responses Data Measured in an Instrumented Flexible Pavement
Journal of Civil Engineering and Construction, 2020
This study presents and analyses the stress-strain responses data measured under real traffic conditions measured between Oct. 2012 to Oct. 2013 on an instrumented flexible pavement section on Interstate 40 (I-40) in the state of New Mexico, USA. Some weather variations data such as moisture and temperature variations at different depths of the pavement over the entire year are also discussed. The moduli of different layers determined using laboratory and field tests are also presented. It is expected that results of this study will be greatly useful to understand the behaviour of flexible pavement. The data presented in this study can be used to validate any constitutive or numerical model developed by readers.
2015
This thesis is lovingly dedicated to our anticipated baby. This thesis also dedicated to my husband, Abdul Motin for his support and encouragement. Figure 3.3: Locations of (a) starting and (b) ending positions for the influence line analysis with standard truck as shown in Fig. 3.2. The successive positions of axle load are given in Table 3. Figure 3.4: Locations of starting positions for the influence line analysis with Michigan trucks (MI-20, MI-14, and MI-13). The first axle of first tandem is placed at the right side of the left transverse joint of the mid slab. The successive and ending positions of the axles loading are given in Table 3. Figure 3.6: Tensile stresses at the top surface of mid-slab along the longitudinal edge with 14-feet joint spacing and asphalt shoulders for the standard truck.
The Effects of Truck Axle Loads and Tire Pressure on the Responses of Flexible Pavement
ERJ. Engineering Research Journal
In recent years, overinflated tire pressure and the consequence of increased heavy vehicles` axle loads on flexible pavements responses have become a major source of worry, because of the higher stress levels induced within the flexible pavement which leads to extra damage. As a result, this research aims to assess the performance of the flexible pavement under varied axle loads and tire pressures of different trucks in Egypt. The 3D-Move V2.1 analysis program is a tool used to calculate the stresses and strains within pavement layers. The main conclusions that can be drawn from the analysis of the results is that there is a direct relation between pavement responses in terms of vertical strain z-z (Ɛz-z), normal strain x-x (Ɛx-x), and vertical displacement (V d) with each of tire pressure and axle load. Furthermore, the pavement responses are affected more by load than tire pressure. The Ɛ z-z is influenced not only by vertical stresses, but also by normal and radial stresses and the elastic modulus of the layer. Also, vertical strain developed at the bottom of the asphalt layer and the subgrade is not affected significantly by tire pressure. In addition, the effects of tire pressure on the horizontal strain at the bottom of the asphalt layer is much more than on the compressive strain above the subgrade. The important conclusion is increasing of wheel loads have a greater impact on rutting deterioration than fatigue. However, increasing tire pressure has a greater impact on fatigue deterioration than rutting.
Effect of Axle Load Spectrum Characteristics on Flexible Pavement Performance
Transportation Research Record: Journal of the Transportation Research Board, 2009
The Mechanistic-Empirical Pavement Design Guide (MEPDG) uses performance models to predict cracking and rutting in flexible pavements. A unique mechanism controls the initiation and accumulation of each distress, but each mechanism can have several causes. Axle repetitions and loads are the main causes of all load-related distress types. MEPDG incorporates axle load spectra to characterize axle loading for a site and uses them to calculate pavement response and damage accumulation. These load distributions have a bimodal shape, and a mixture of two continuous distributions can be used to model them. In this paper, closed-form solutions are developed to estimate the characteristics of a mixture of bimodal axle load distributions. The observed axle load spectra from 14 sites in different states were used to relate load distribution characteristics to predicted flexible pavement performance. The overall mean and other characteristics of a bimodal axle load distribution explained the variations in expected flexible pavement performance. Cracking, surface rutting, and ride quality are related to the fourth root of the fourth moment of axle load distributions. Rutting in the hot-mix asphalt layer is strongly associated with the overall mean, but in base and subbase layers it is related to the 95th percentile load of axle load spectra. These findings imply that cracking, rutting, and roughness growth in flexible pavements are caused mainly by axle load distributions having heavier tails with infrequent extreme loads. Heavier loads appear to cause more cracking; a higher number of load repetitions is more critical in developing additional surface rutting in flexible pavements. Axle load spectra were used to develop the Mechanistic-Empirical Pavement Design Guide (MEPDG). Use of these load distributions provides a direct and rational approach for the analysis and design of pavement structures to estimate the effects of actual traffic on seasonal pavement response and distress. In the AASHTO Guide for Design of Pavement Structures, a mixed traffic stream of different axle loads and configurations is converted into a design traffic number by transforming each expected axle load into an equivalent number of 18-kip single-axle loads, known as equivalent single-axle loads (ESALs) (1). Load equivalency factors are used to determine the number of ESALs for each axle load and configuration. These factors are based on the present serviceability index (PSI) concept and depend
StressStrain characteristics of flexible pavement using Finite Element Analysis
2010
Design of flexible pavement is largely based on empirical methods using layered elastic and twodimensional finite element (FE) analysis. Currently a shift underway towards more mechanistic design techniques to minimize the limitations in determining stress, strain and displacement in pavement analysis. This research documents the use of 3D finite element application for predicting mechanical behavior and pavement performance subjected to various traffic factors. Different axle configuration, tire imprint areas and inflation pressure are investigated here to analyze the considerable impact on pavement damage initiation from fatigue and permanent deformation point of view. In this study, flexible pavement modeling is done using ABAQUS software in which model dimensions, element types and meshing strategies are taken by successive trial and error to achieve desired accuracy and convergence of the study. Thus proper tire imprint area is determined to apply in economical design of pavement for various axle configurations.
Transportation Research Record, 2003
A direct and simple method (YONAPAVE) for evaluating the structural needs of flexible pavements is presented. It is based on the interpretation of measured FWD deflection basins using mechanistic and practical approaches. YONAPAVE estimates the effective Structural Number (SN) and the equivalent subgrade modulus independently of the pavement or layer thicknesses. Thus, there is no need to perform boreholes which are expensive, time consuming and disruptive to traffic. Knowledge of the effective SN and the subgrade modulus, together with an estimate of the traffic demand, allows for the determination of the overlay required to accommodate future needs. YONAPAVE simple equations can be solved using a pocket calculator, making it suitable for rapid estimates in the field. The simplicity of the method, and its independency of major computer programs, makes YONAPAVE suitable for estimating the structural needs of a road network using FWD data collected on a routine or periodic basis along the network roads. With increasing experience and confidence, YONAPAVE can be used as the basis for NDT structural evaluation and overlay design at the project level.
Stress-Strain Characteristics of Flexible Pavement by Finite Element Method
International Journal For Computational Civil and Structural Engineering, 2011
Design of flexible pavement is largely based on empirical methods using layered elastic and twodimensional finite element (FE) analysis. Currently a shift underway towards more mechanistic design techniques to minimize the limitations in determining stress, strain and displacement in pavement analysis. This research documents the use of 3D finite element application for predicting mechanical behavior and pavement performance subjected to various traffic factors. Different axle configuration, tire imprint areas and inflation pressure are investigated here to analyze the considerable impact on pavement damage initiation from fatigue and permanent deformation point of view. In this study, flexible pavement modeling is done using ABAQUS software in which model dimensions, element types and meshing strategies are taken by successive trial and error to achieve desired accuracy and convergence of the study. Thus proper tire imprint area is determined to apply in economical design of pavement for various axle configurations.
The Response of Pavement to The Multi-Axle Vehicle Dynamic Load
—In order to study the response of pavement to the multi-axle vehicle dynamic load, three-dimensional finite element analysis model of asphalt pavement under a multi-axle vehicle dynamic load was established. The structure of asphalt pavement simplified to four layers. The material of asphalt surface layer has the property of viscoelastic and the materials of the other layers are assumed to be linear elastic. The results can provide a reference for the design and analysis of pavement performance and pavement structure.