Fatigue of plain concrete in uniaxial tension and in alternating tension-compression experiment and results

Abstract

This research program deals with fatigue of plain concrete subjected tocyclic uniaxial tensile loadings or alternating uniaxial compression-tension.In the main program more than 250 constant amplitude tests at a frequency of 6Hz have been performed. One concrete composition was investigated (averagecompressive strength: 50 N/mm² and average tensile strength: 2.6 N/mm²). The dynamic stress alternated between two stress-strength levels, namely, 40% to 90% of the static tensile strength for the maximum level, and 40%to 0 (tension) or 0 to 30% (compression) for the minimum level. The numbersof cylces to failure have been related to these maximum and minimum levelsand presented in Wöhler-diagrams (S-N). Drying as well as sealed specimenswere tested. By means of statistical methods the effect of the variabilityof the static strength on the scatter of the dynamic results was determined.Cyclic deformations were also recorded and given as a function of the cycleratio (n/N). The secondary creep velocity was compared with the numbers ofcycles to failure. The aim of this report is to describe the testing equipment and to presentthe results. The theoretical approach will be published later.