EFFECTS OF IRREGULARITIES ON THE DYNAMIC RESPONSE OF PAVEMENTS IN NON-DESTRUCTIVE TESTING. INTERIM REPORT
A computer program using finite elements was developed to simulate the response of defective pavements (i.e., pavements with horizontal delaminations, voids of different sizes, and vertical cracks) to dynamic loads applied at the surface. The solution of the finite element model is carried out in the time domain to obtain transient responses and steady-state amplitudes. These are easily obtained by applying the Fast Fourier Transform to the transient responses. The results obtained with this procedure were compared with those computed directly in the frequency domain with a boundary element formulation. The effect of horizontal delaminations, voids, and vertical cracks on the motions that would be recorded at the surface when an impulse is applied (also at the surface) was investigated. It was found that voids and delaminations can be easily recognized, if they are not too deep or at the interface of two layers with very different elastic properties. The impulse excites frequencies in one of two ranges: the first range corresponds to flexural waves traveling along the surface; the second to more traditional P waves traveling up and down. Each range offers some advantages and disadvantages. The flexural range provides a larger contrast and, therefore, easier identification when applicable. Vertical cracks have also a clear signature when they are surface piercing; they are, however, difficult to detect with the methods explored here when they are at depth and do not reach the surface.
- Research study title: Automated Equipment for Characterizing the Properties and Thicknesses of Pavements.
University of Texas, AustinCenter for Transportation Research, 3208 Red River Street
Austin, TX United States 78705
Austin, TX United States 78763-5051
Washington, DC United States 20590
- Chiang, C C
- Roesset, J M
- Stokoe II, K H
- Publication Date: 1994-12
- Features: Figures; References;
- Pagination: 232 p.
- TRT Terms: Computer programs; Delamination; Dynamic loads; Fast Fourier transforms; Finite element method; Nondestructive tests; Pavements; Void ratios
- Uncontrolled Terms: Dynamic response; Voids
- Old TRIS Terms: Vertical cracks
- Subject Areas: Design; Highways; Pavements; I22: Design of Pavements, Railways and Guideways; I23: Properties of Road Surfaces;
- Accession Number: 00720268
- Record Type: Publication
- Report/Paper Numbers: FHWA/TX-1995/1243-2, Res Rept 1243-2, CTR 0-1243-2
- Contract Numbers: Study 0-1243
- Files: TRIS, USDOT, STATEDOT
- Created Date: Apr 24 1996 12:00AM