NATURAL FREQUENCIES OF STRUCTURES FOR DESIGNERS

By separating a vibration problem into two distinct parts, one concerned only with the spring forces in the structure and the other only with the inertial forces imposed by the mass carried, easy calculations can be used to solve fairly complex structures. Naturally, since this method does not concern itself with damping forces it will not tackle problems concerned with the amplitude of vibration caused by a particular excitation. It will, however, deal with one of the major questions in design, 'what are the natural frequencies of the particular structure, do any of them correspond with a known dynamic load and, if so, how can the structure be altered to change that natural frequency sufficiently?' the method is based on the simple formula for the frequency of vibration of a mass hanging on a spring and shows that it is possible to reduce the difficulty of structural problems until mere hand calculations will give sufficiently accurate values for use in design. The method will find the lowest natural frequency, or the frequency of any other mode shape chosen by an engineer, including the cases of partial or sway vibrations. /Author/TRRL/

  • Availability:
  • Corporate Authors:

    Institution of Structural Engineers

    11 Upper Belgrave Street
    London,   United Kingdom  SW1X 8BH
  • Authors:
    • BOLTON, A
  • Publication Date: 1978-9

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 245-253
  • Serial:
    • Structural Engineer
    • Volume: 56A
    • Issue Number: 9
    • Publisher: Institution of Structural Engineers
    • ISSN: 1466-5123

Subject/Index Terms

Filing Info

  • Accession Number: 00188292
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Mar 28 1979 12:00AM