The aim of the article is the study of a 1/4 scale model of a twin span composite bridge. The aim is to study the effects of shrinkage, the effects of settlement of the supports, the effects of overloading, the ultimate loads and to verify the hypothesis of the classical calculation method as they affect different phenomena. In the absence of support settlement following concreting of the slab or of the initial prestressing, the concrete cracks in the zone of negative moment where the stress in the slab reaches a value of the same order of magnitude as the tensile strength obtained in tests on specimens. Following cracking, a fraction of the strength remains in the slab, but the consideration of this fraction in the calculation does not influence, in the case of the model, the values of the indeterminate reactions. The model tests provide confirmation that the behaviour conforms to the hypothesis. The effects of long term settlement of supports in the model satisfactorily confirm the method of coefficients of equivalence. As regards Sattler's theory this gives results which conform with experience. The coefficient of equivalence found experimentally in the course of this study is the same as that obtained during the study of shrinkage. The study of overloading demonstrates the participation of the uncracked slab both under positive and under negative moments. As regards the participation of the cracked slab in the zone of negative moment, it diminishes when the overload increases. The classical calculation which neglects this portion of the tensile strength in the cracked slab, permits one to determine the values of the indeterminate reactions with a sufficiently high degree of accuracy. The collapse tests under symmetrical overloading display the classical collapse mode: formation of plastic hinges under the loading and at the central supports. The collapse load corresponds sufficiently well to the results of the calculations. /TRRL/

  • Corporate Authors:

    Laboratoire Central des Ponts et Chausees (LCPC)

    Boulevard Lefebvre 58
    Paris Cedex 15,   France  F-75732
  • Authors:
    • Tothstre
  • Publication Date: 1975-1-2


  • French

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00168160
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Analytic
  • Files: ITRD, TRIS
  • Created Date: Jun 14 1978 12:00AM