Træthed og reststyrke i beton: og andre viskoelastiske materialer med ældning

The DVM-theory (Damaged Viscoelastic Material) previously developed by the author to predict lifetime of non-aging viscoelastic materials (like wood) is generalized in this paper such that aging viscoelastic materials such as concrete subjected to variable load can also be considered. Lifetime (real time or number of cycles) is predicted as a function of load amplitude, load average, fractional time under maximum load, and load frequency. The analysis includes prediction of residual strength during the process of load cycling. It is concluded that number of cycles to failure is a poor design criterion. A simple time criterion is much better. The theory is successfully compared with methods previously presented in the field of concrete fatigue. Algorithms and design graphs are developed which can be used in fatigue design of concrete products.