DESIGN OF MACHINE FOUNDATIONS ON PILES--DISCUSSION

The use in the paper of one arbitrary value of damping to represent all pile foundations is not justifiable. This approach was used for rigid footings but it is now well known that damping varies with other paramters such as footing mass, vibration mode, etc. Footings with large mass have lower damping than those with small mass and the theoretical estimate of damping should reflect this. Exactly the same is true for pile foundations. The use of six uncoupled single-degree-of-freedom modes for the vibration of pile footings is incorrect. The response of footings to horizontal excitation and to moments in a vertical plane is always coupled. To realistically predict response to horizontal excitation, coupled response must be included in the theoretical analysis. The practical example presented by the authors is unfortunate in that only subresonant response amplitudes are predicted and the experimental response curve is not known. The prediction of other than resonant amplitudes is relatively insensitive to both dynamic stiffness and to dampling.

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  • Accession Number: 00178884
  • Record Type: Publication
  • Report/Paper Numbers: ASCE 13838 Proceeding
  • Files: TRIS
  • Created Date: Sep 27 1978 12:00AM