CONTRIBUTION TO THE STUDY OF THE CREEP OF PRESTRESSING STEEL? DETERMINATION OF CREEP AND RELAXATION THRESHOULDS

CONTRIBUTION A L[ETUDE DU FLAUAGE DES ACIERS DE PRECONTRAINTE? DETERMINATION DES SEUILS DE FLUAGE ET DE RELAXATION

During the tensioning process of high-strength steel cables used as reinforcement in prestressed concrete, it often happens that the measured extension is greater than the calculated extension. One explanation of this phenomenon is the possibility of creep in the steel when the stresses applied are large and exceed a certain threshold of plastic flow. Numerous creep and relaxation tests carried out on prestressing steel varying in quality show that there exists a creep threshold and a relaxation threshold, which are practically identical and are comprised between 0.55R and 0.75R (R being the tensile strength). Below these thresholds, phenomena exist but are negligible. Results of tensile tests shol that these thresholds correspond fairly well to the limit of proportionality. The conventional elastic limit at 0.1%, which is normally used, could be assimilated to a steel plastifying threshold. If prestressing wires are maintained at stress levels comprised between 0.8R and 0,85 during ten minutes, creep occurs, which results in extension exceeding between 1% and 15% of the calculated value. ;TRRL;

  • Corporate Authors:

    Central and Regional Labs of Bridges & Highways,Fr

    58 Boulevard Lefebvre
    75732 Paris Cedex 15,   France 
  • Authors:
    • Olivie, F
  • Publication Date: 1973-6-29

Language

  • French

Media Info

  • Features: Figures; Photos; References; Tables;

Subject/Index Terms

Filing Info

  • Accession Number: 00125674
  • Record Type: Publication
  • Report/Paper Numbers: Thesis
  • Files: ITRD, TRIS
  • Created Date: May 14 1976 12:00AM