Fatigue Strength of Concrete Under Varying Flexural Stresses.

Previous fatigue studies of concrete were in many cases not representative of the load conditions of actual structures since in these tests the applied loads fluctuated between constant minimum and maximum values. In the present investigation plain concrete specimens were subjected to repeated flexural stresses according to various load histories; the maximum load within a test was varied between two limits, or rest periods were introduced. The results were interpreted according to various physical models and compared to the Miner rule. This hypothesis may give conservative or unsafe predictions of the fatigue strength depending on the load program. An Improved design method Is suggested. [ABSTRACT FROM AUTHOR]