Effect of loading frequency on tensile fatigue behavior of ultra-high-strength engineered cementitious composites

The ultra-high-strength engineering cementitious composites demonstrates pseudo strain hardening behavior when subjected to uniaxial tension, making it a promising material for enduring repeated or fatigue loads. Extensive research has been conducted on the quasi-static, dynamic, and fatigue behavior of this composites. However, due to the challenges of conducting direct tensile testing on concrete, investigations into the tensile fatigue behavior of ECC, particularly for ultra-high-strength ECC, remain limited. The fatigue behavior of concrete can be influenced by various factors. This study focuses on the impact of loading frequency. Several series of tensile fatigue tests were conducted under different loading frequencies and stress levels. The test results revealed that fatigue life increases with higher applied loading frequencies and decreases with increasing stress levels. The analysis of the test results includes the examination of failure modes, fatigue life, deformation, and secondary strain rates. A probabilistic model of fatigue failure, considering the discreteness of the initial static strength, was proposed based on the fatigue life. This model aligned well with the experimental results, providing valuable insights into the behavior of ultra-high-strength ECC under tensile fatigue conditions.