Abstract
This paper describes an effect of artificial crack length on fatigue load carrying mechanism of cracked reinforced concrete (RC) beams without stirrups. To make clear the mechanism, cyclic loading experiments and finite element (FE) analyses were conducted by using the specimens which had different length of artificial cracks. The experimental results indicated that the load carrying mechanism was governed by tied arch effect due to horizontal cracks which was propagated from artificial crack tips regardless of loading conditions. In case of the beams whose static strength was enhanced due to tied arch effect, the number of cycles at failure was the same as the sound beam under the cyclic load of 40% upper limit load ratio. It was demonstrated that the reason was localization of relative damage accumulation area caused by linearization of the load path. The analytical results showed that the linearization occurred by stress concentration at the position of crack tips which existed inside of B-region. It was made clear that when the crack tips existed inside of D-region, horizontal cracks were easy to be propagated with increase in the number of loading cycles.
