Results from fuzzy model and BAKFAA are reasonably comparable.
#Fwd backcalculation software
Surface moduli from this fuzzy model are compared to those from BAKFAA, a backcalculation software developed by Federal Aviation Administration (FAA).
Recursive Least Square (RLS) error is used to improve the accuracy of the model by updating the MLFE parameters. These loads, deflections, and modulus of elasticity are then trained by MLFE rule to develop a fuzzy model. Backcalculation Tool (BcT, v1.0) was made available to generate backcalculation inputs (using the EVERCALC algorithm) from falling weight deflectometer (FWD) files for use in rehabilitation design.
#Fwd backcalculation trial
To generate training dataset, an axi-symmetric Finite Element Model (FEM) is developed to simulate surface deflections in response to given load and trial layer modulus. Specifically, Modified Learning From Example (MLFE) based fuzzy rule is employed to determine modulus from the magnitude of FWD test loads and maximum deflection. On the other hand, when the backcalculation is based on dynamic analysis of the FWD test, the resulting moduli are quite insensitive to the depth to bedrock if this depth. This study develops a fuzzy model to backcalculate modulus of pavement layers. Depth to bedrock can have a significant effect on the moduli of the surface layer, base, and subgrade backcalculated from Falling Weight Deflectometer (FWD) tests when the calculations are performed using a static analysis. Thus, the backcalculation procedure based on LET, 64 or static backcalculation inevitably leads to erroneous results. By using the non-destructive device the falling weight deflectometer, it is a proven method of achieving a sound mechanistic design of the new layer thickness. Pavement rehabilitation method and timing depend on the existing stiffness or modulus of pavement layer materials. Backcalculation of road layer elastic moduli is an important procedure in determining stresses and strains in road structures due for overlay design. 1096, respectively.Backcalculation of modulus values from Falling Weight Deflectometer (FWD) data is one of the most popular practices all over the world for pavement evaluation. The attenuation patterns of the surface layer modulus and the base layer modulus in the damage stage are described as E a = 421100 * N - 0.6119 and E b = 128000 * N - 0. The backcalculated base layer modulus always declines with the increasing loading repetitions. The ratio of the measured surface layer modulus based on the PSPA test to the backcalculated one based on the FWD test ranges between 2.06 and 2.71. The modulus values of the surface layer measured from PSPA tests are obviously larger than those backcalculated based on deflection basins. That is the modulus of the surface layer increases with the APT load repetitions firstly and then decreases with the rise of the repetitions. It was found that the variation pattern of surface layer modulus based on field FWD measurements was consistent with the one measured from PSPA tests. The variation patterns of layer moduli obtained by FWD and PSPA tests were calculated and compared after the temperature was corrected to 20 ℃.
#Fwd backcalculation portable
Two non-destructive testing (NDT) methods, named falling weight deflectometer (FWD) technique and portable seismic property analyzer (PSPA) test, were used to obtain the layer moduli of asphalt pavement during the APT test.
A full-scale experimental section was constructed and tested using the APT facility. This research aimed to investigate the attenuation mode of the layer modulus of asphalt pavement in accelerated pavement testing (APT).