Proper estimation of the natural frequency of the machine foundation soil system is very important, since piles may be necessary to increase the stiffness of the system in order to bring it to a proper natural frequency, i.e. either less than half or greater than twice the operating frequency of the machine. In the case of dynamic analysis, the method of equivalent antilever has some important limitations. The idealization is too simple and hence unrealistic. It is difficult to take the important factors like energy dissipation and boundary conditions into account. Also, variations in the length of pile, diameter, and skin friction, etc., cause changes in the resonant frequency and amplitude of vibration. It is felt that, in the equivalent cantilever system described in the paper, the dynamic stiffnesses should be calculated instead of the static ones. In the case of pile groups, the natural frequency taking the group effect into account needs to be taken, since investigations have shown that, up to a spacing of eight times the pile diameter, the natural frequency of the group increases with an increase in pile spacing.

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  • Supplemental Notes:
    • This paper is a discussion of ASCE Proceeding Paper 13158 by Jogeshwar P. Singh, Neville C. Donovan, and Adrianus C. Jobsis.
  • Corporate Authors:

    American Society of Civil Engineers

    345 East 47th Street
    New York, NY  United States  10017-2398
  • Discussers:
    • Vijayvargiya, R C
    • Ranjan, G
  • Publication Date: 1978-7

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Filing Info

  • Accession Number: 00179322
  • Record Type: Publication
  • Report/Paper Numbers: ASCE 13902 Proceeding
  • Files: TRIS
  • Created Date: Sep 14 1978 12:00AM