Mechanistic design of flexible pavement is usually carried out by using Linear Elastic Theory (LET); it must use appropriate values of the equivalent asphalt concrete elastic modulus to evaluate stresses and strains in a linear elastic multi-layer. This paper aims to identify some relations to estimate the value of loading frequency, representative of the real strain pulse frequency spectrum, to be used in calculating the stiffness modulus of the asphalt concrete layers; by this way, an equivalent linear elastic structural analysis can be carried out. In order to achieve these aims, many transient load simulations were performed by means of the ViscoRoute software based on the visco-elastic model. Once variables that affect the representative frequency value were detected, over 215 variable combinations, representative of real conditions, were randomly generated. For each of them, the visco-elastic analysis was performed, and thus the stiffness modulus and the corresponding loading frequency were back-calculated by minimizing the residuals between linear elastic and visco-elastic peak strains. The representative frequency values, calculated for these configurations, were related to the significant variables by means of a multivariate regression. The model was developed separately for each of the three directions, according to the anisotropic behavior of pavement under moving loads. Finally, the procedure was validated by applying it to a series of climatic and load configurations of an existing pavement. The study provides a useful and simple tool to be used in conjunction with LET for pavement design, and that allows to take into account all significant parameters.
EVALUATION OF THE REPRESENTATIVE LOADING FREQUENCY FOR LINEAR ELASTIC ANALYSIS OF ASPHALT PAVEMENTS
LOSA, MASSIMO;
2012-01-01
Abstract
Mechanistic design of flexible pavement is usually carried out by using Linear Elastic Theory (LET); it must use appropriate values of the equivalent asphalt concrete elastic modulus to evaluate stresses and strains in a linear elastic multi-layer. This paper aims to identify some relations to estimate the value of loading frequency, representative of the real strain pulse frequency spectrum, to be used in calculating the stiffness modulus of the asphalt concrete layers; by this way, an equivalent linear elastic structural analysis can be carried out. In order to achieve these aims, many transient load simulations were performed by means of the ViscoRoute software based on the visco-elastic model. Once variables that affect the representative frequency value were detected, over 215 variable combinations, representative of real conditions, were randomly generated. For each of them, the visco-elastic analysis was performed, and thus the stiffness modulus and the corresponding loading frequency were back-calculated by minimizing the residuals between linear elastic and visco-elastic peak strains. The representative frequency values, calculated for these configurations, were related to the significant variables by means of a multivariate regression. The model was developed separately for each of the three directions, according to the anisotropic behavior of pavement under moving loads. Finally, the procedure was validated by applying it to a series of climatic and load configurations of an existing pavement. The study provides a useful and simple tool to be used in conjunction with LET for pavement design, and that allows to take into account all significant parameters.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
