There is an increasing demand from researchers to simulate the fatigue behaviors of RC bridge slabs. Previous researches recorded that the fatigue life of RC slabs under moving load is lower than that under fixed pulsating load. Most of previous studies focused on the modeling of fatigue behaviors of RC slabs reinforced with deformed bars. But, many existing RC slabs are reinforced with plain bars, and suffer from fatigue damages. According to previous studies, the analytical method for the fatigue life prediction of these slabs has not been conducted.
An experimentally verified numerical method is presented in this study to simulate the fatigue behaviors of RC slabs reinforced with plain bars under moving load. This numerical method is based on the bridging stress degradation concept. The bond-slip effect between a reinforcing bar and surrounding concrete is taken into consideration with its degradation under repetitive load.
Fatigue analysis of RC slabs under moving load is conducted using this numerical method for obtaining the numerical results. Repetition of moving load leads to the cracked elements propagation. By applying bridging stress degradation concept on cracked elements, overall RC slab stiffness decreases with increasing number of cycles to fatigue failure. This procedure leads to an increasing of center displacement evolution with increasing number of cycles. The slab at a higher fatigue load ratio shows a shorter fatigue life than that at a lower fatigue load ratio. The comparison of center displacement evolution between experimental and analytical results at different moving load levels is conducted and it shows a good agreement between them. The numerical results of fatigue life provide a good agreement with the experimental results.
According to this study, the applicability of bridging stress degradation concept can be extended to predict the fatigue life of RC slab reinforced with plain bars.