Dynamic simulation of falling weight deflectometer tests on flexible pavements using the spectral element method: forward calculations

2009 ◽  
Vol 36 (6) ◽  
pp. 944-956 ◽  
Author(s):  
Simon Grenier ◽  
Jean-Marie Konrad ◽  
Denis LeBœuf
Keyword(s):  
Dynamic Analysis ◽  
Spectral Element Method ◽  
Flexible Pavements ◽  
Computer Code ◽  
Spectral Element ◽  
Falling Weight Deflectometer ◽  
Viscous Effects ◽  
Damping Material ◽  
Falling Weight ◽  
Element Method

A dynamic analysis based on the spectral element method is described for the interpretation of falling weight deflectometer (FWD) tests on flexible pavements. This dynamic approach was implemented in the computer code Dynamic Analysis of Pavement - Université Laval (DYNAPAV-UL) that includes both frequency-independent hysteretic damping and frequency-dependent viscous damping material models. A parametric study was conducted on a four-layer flexible pavement to evaluate the influence of different layer moduli on deflection basins and deflection histories. The viscous behaviour of the asphalt concrete layer was also investigated. While the deflection basin currently used in static methods gives some details of the pavement response under transient loading, the simulations of FWD tests using the dynamic model suggest that the time histories should be included as well for the interpretation of FWD deflection measurements. In fact, important dynamic phenomena due to inertial effects and viscous effects are only revealed by deflection histories.

Dynamic interpretation of falling weight deflectometer tests on flexible pavements using the spectral element method: backcalculation

2009 ◽  
Vol 36 (6) ◽  
pp. 957-968 ◽  
Author(s):  
Simon Grenier ◽  
Jean-Marie Konrad
Keyword(s):  
Spectral Element Method ◽  
Flexible Pavements ◽  
Spectral Element ◽  
Falling Weight Deflectometer ◽  
Dynamic Approach ◽  
Dynamic Interpretation ◽  
Minimization Technique ◽  
The Time Domain ◽  
Falling Weight ◽  
Element Method

A robust backcalculation methodology that uses the Levenberg–Marquardt iterative minimization technique is presented to identify the value of unknown layer parameters from falling weight deflectometer (FWD) tests using a dynamic approach based on the spectral element method. Backcalculation is performed in the time-domain with 20 observations on each deflection history. The efficiency of the proposed methodology is demonstrated by interpreting FWD tests on three flexible pavements that cover a variety of structures, soil, and bedrock conditions. Results indicate that the dynamic approach is capable of simulating quite well the measured deflection histories using effective backcalculated moduli. In addition, comparison of critical strains between static and dynamic interpretation of FWD tests indicates that both approaches predict similar traction strains at the bottom of the asphalt concrete layer. However, the prediction of the compression strain in the subgrade with the static approach is erratic compared with the dynamic method.

Nonlinear spectral dynamic analysis of guyed towers. Part I: Theory

2004 ◽  
Vol 31 (6) ◽  
pp. 1051-1060 ◽  
Author(s):  
A M Horr
Keyword(s):  
Dynamic Analysis ◽  
Nonlinear Dynamic ◽  
Spectral Element Method ◽  
Spectral Element ◽  
Space Structures ◽  
Large Space ◽  
Analysis And Design ◽  
Large Space Structures ◽  
Guyed Towers ◽  
Element Method

One of the important parameters in the analysis and design of large space structures is to account for the dynamic forces induced by wind and the subsequent progressive collapse. During the past two decades, problems of extreme loading conditions have been considered by some authors, and special attention has been devoted to the collapse modes. Nonlinear time history dynamic analysis, involving the post-buckling characteristics of the space structures, may be analyzed using the conventional finite element method. However, to guarantee stability and accuracy of the solution, the number of elements used to model the structure may be very large. In this respect, the nonlinear spectral element method (SEM) is developed for analyzing dynamic problems in large space structures. Through use of a computer program, the proposed method has been used to obtain the nonlinear dynamic response of guyed power transmission towers under severe wind loading condition. Key words: nonlinear dynamic analysis, space structures, guyed towers, spectral element method.

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