Constant-amplitude tests on plain concrete in uniaxial tension and tension-compression

This research report is the continuation of Stevin Laboratory Report No. 5-81-7 "Fatigue of plain concrete in uniaxial tension and in alternating tension-compression" [1], in which test set-up, loading equipment and preliminary results have been described. The present report deals with the total set of constant-amplitude tests on concrete loaded in direct tension and in tension-compression. This set includes mainly fatigue tests at 6 Hz on specimens having one concrete composition (quality B 45). Tests were performed on "drying" as well as on "sealed specimens". Besides these tests in an additional program, the effect of concrete quality and test frequency was also studied. The results are presented in S-N relations and a Goodman diagram. It can be concluded from this diagram that stress-reversals cause extra damage, which significantly reduces fatigue life. Based on cyclic deformation, which was recorded continuously during the fatigue tests, relations were established between fatigue life on the one hand and secondary creep velocity and ultimate cyclic strain on the other hand. Particularly the secondary creep velocity proved to be a good predictor for life of concrete subjected to fatigue loading.Design & ConstructionCivil Engineering and Geoscience