A method of dynamic analysis for vertical, torsional and lateral free vibrations of suspension bridges is developed that is based on linearized theory and a finite-element approach. It involves 2 steps: (1) specification of potential and kinetic energies of vibrating structure, leading to derivation of equations of motion by Hamilton's Principle, (2) use of a finite-element technique to: (a) discretize the bridge, (b) select displacement models, (c) derive stiffness and inertia properties, and (d) form matrix equations of motion. Stiffness and inertia properties are evaluated by expressing potential and kinetic energies of an element in terms of nodal displacements. Numerical examples are presented to illustrate the applicability of the analysis and to investigate dynamic characteristics of suspension bridges. The method eliminates the need to solve transcendental frequency equations, simplifies determination of energy stored in the bridge, and represents an accurate tool for calculating natural frequencies and modes by means of a digital computer. The method is illustrated by calculating modes and frequencies of a bridge and comparing them with measured frequencies.

  • Corporate Authors:

    California Institute of Technology

    Earthquake Engineering Research Laboratory
    Pasadena, CA  United States  91125

    National Science Foundation

    1800 G Street, NW
    Washington, DC  United States  20550
  • Authors:
    • Abdel-Ghaffar, A M
  • Publication Date: 1976-5

Media Info

  • Pagination: 372 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00146767
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: EERL-76-01 Final Rpt.
  • Contract Numbers: NSF-ATA74-19135
  • Files: TRIS
  • Created Date: Feb 16 1977 12:00AM