A theoretical study is made of the vibration of bridges subjected to moving loads. The coefficient of impact is defined as the quotient of the deflections caused at one point by a moving load, by that of the same static load. An investigation is conducted into material fatigue (concrete, steel and prestressed concrete) resulting from vibration, and empirical formulae are proposed which establish a relation between the strength of the material after a number of cycles, the amplitude of the dynamic force and the resistance to static stress. Some of the conclusions reached were as follows: the modulus of elasticity of the concrete diminishes with an increase in the number of load cycles; the stress/strain chart is variable but tends to reach a final stability; generally speaking, the difference in the quality of steel is negligible as regards the definition of its fatigue behaviour; when cycle loading applied to a prestressed beam does not result in cracking, the strength does not seem to be markedly reduced; but cracking supposes an appreciable drop in strength. /TRRL/

  • Corporate Authors:

    Ultimas Noticias de Hormigon Pretensado

    Instituto Eduardo Torroja
    Madrid 16,   Spain 
  • Authors:
    • Paez, A
  • Publication Date: 1972-1-3


  • Spanish

Media Info

  • Features: References;
  • Pagination: p. 23-45
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00125191
  • Record Type: Publication
  • Source Agency: Transportation & Soil Mechanics Laboratory, Spain
  • Files: ITRD, TRIS
  • Created Date: Nov 18 1975 12:00AM