This article describes the results of flexural fatigue tests carried out on plain and fibrous concretes using a cyclic flexural loading machine. This machine is capable of fatigue testing large beams in 4 point bending with load cycling above zero for up to 10 million cycles at rates of up to 20 Hz. Some 50 fatigue tests were completed supported by a further 500 strength and control tests. The changes in strain profile, deflection, electro-dynamic modulus and ultrasonic pulse velocity were observed. Deflection measurements were made on the top surface of the test specimens at midspan using two linear variable transformers (LVDT) each situated about 10 mm from each side of the beams. Strain measurements were taken at various depths at midspan using LVDT's similar to those used for deflection measurement. A novel adaptation of the standard electrodynamic modulus procedure enabled concrete deterioration to be continuously monitored when subjected to either slow rate ramp loading or fatigue tests. These methods provided a complete series of strain, deflection and crack development histories. The results showed that the real stress ratio below which there will be no failure was about 30% for plain concrete (applicable to all rates of loading). Corresponding values for fibrous concrete were approximately 50% for steel fibre content of 1 or 2% by volume, rising to 60% for a concrete containing 3% fibre. There were few prior indications of failure of either plain or fibrous concrete in fatigue. When assessing a task in which concrete fatigue loading is a consideration, a knowledge of the range of loading rates may be as crucial as a knowledge of the stress being applied. (TRRL) (Author/TRRL)

  • Availability:
  • Corporate Authors:

    British Society for Strain Measurements

    Suite 7, Exchange Building, Quayside
    Newcastle-Upon-Tyne,   England 
  • Authors:
    • Butler, J E
  • Publication Date: 1990-11


  • English

Media Info

  • Features: References;
  • Pagination: p. 135-9
  • Serial:
    • Strain
    • Volume: 26
    • Issue Number: 4
    • Publisher: British Society for Strain Measurements
    • ISSN: 0039-2103

Subject/Index Terms

Filing Info

  • Accession Number: 00623768
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Jul 31 1992 12:00AM