On the correlation between the stable rate of deformation growth and the fatigue life in concrete

For the reliable and economical design of concrete structures under fatigue loading, a comprehensive understanding and accurate prediction of concrete fatigue life, especially under complex loading scenarios with variable amplitudes, is critical.Recent experimental studies on concrete compressive fatigue behavior demonstrate that fatigue life is closely linked to the strain rate in the second phase of strain development.Based on extensive testing of cylindrical specimens, a linear relationship between the strain rate in this phase and the number of cycles to failure has been observed in double-logarithmic space.This correlation provides a more consistent evaluation of fatigue life with significantly less scatter compared to traditional S-N curves.Moreover, the predictive capability of the strain-rate criterion can be used to estimate the fatigue life of runouts, which also enables the possibiliy of highly accelerated fatigue tests.This contribution extends the analysis of the linear correlation across a broader range of fatigue stress configurations and varied parameters.In addition to compressive fatigue behavior observed through cylindrical tests, experimental data on tensile fatigue, using notched three-point bending tests (3PBT), and shear fatigue, using punch-through shear tests (PTST), are evaluated.Furthermore, this study re-evaluates the effect of loading sequence-a key factor in fatigue design-by applying the strain rate criterion across different stress states.