FWD-DYN: A Computer Program for Forward Analysis and Inversion of Falling Weight Deflection Data

Details

• Creators:
  Foinquinos, Rafael ; Roesset, Jose M. ; Stokoe, Kenneth H. II
• Corporate Creators:
  University of Texas at Austin. Center for Transportation Research
• Corporate Contributors:
  Texas Department of Transportation. Research and Technology Implementation Office
• Subject/TRT Terms:
  Computer Programs Data Analysis Deflection Tests Falling Weight Deflectometers Manuals Pavement Maintenance
• Publication/ Report Number:
  TX-94-1970-1 F
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; Texas
• Edition:
  Final Report
• Corporate Publisher:
  University of Texas at Austin. Center for Transportation Research
• Abstract:
  A computer program FWD-DYN has been developed to perform forward analyses simulating the Falling Weight Deflectometer test, and to perform inversion of actual field data to estimate the Young's moduli of the surface layer, the base and the subgrade of a pavement system. In the first case the dynamic displacements at various points along the surface are computed under the effect of a transient impact load distributed over a small circular area. The analysis assumes that the layers are horizontal, that they extend to infinity in the horizontal directions and that their properties are constant over the extent and thickness of each layer. It is further assumed that all materials are linearly elastic with a very small amount of frequency independent, hysteretic type damping. The analyses are performed first in the frequency domain then converted to the time domain using the Fast Fourier Transform (FFT). Details of the formulation are presented. For the inverse analysis three options are available: to use only the peak displacements (as is done normally at present); to use a complete dynamic analysis in each cycle of iteration with the experimental data, or to use an intermediate procedure in which the dynamic motions recorded at each station are used to estimate first what would be the static displacements, and a static inversion is then performed. These three options are discussed and documented. Using the computer program, a number of parametric studies were conducted (with the forward analysis option) to assess the sensitivity of the results to variations in the layer moduli, the thickness of the layers and the depth to bedrock. These studies complement those which had been carried out in previous projects and are intended to illustrate the capabilities and potential of the FWD, serving also as a basis for the inversion procedure adopted in the computer program. A user's manual of the program is included.
• Format:
  PDF
• Funding:
  7-1970
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:955fc81bd56afe955d517b71433765adc1c717e8da6a01ca7246d1bad4376dc4c4fb3e82545a9aeee4ef4e7919a671994fd7bd9a8fa1cf8def2ff108b0e4d72e
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/86183/dot_86183_DS1.pdf
• File Type:
  [PDF - 1.21 MB ]