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Shear Fatigue Simulation of RC Beams Subjected to Fixed Pulsating and Moving Loads

E. Gebreyouhannes, N. Chijiiwa, C. Fujiyama and K. Maekawa

Journal of Advanced Concrete Technology, 6(1) 215-226, 2008

The fatigue behavior of RC beams subjected to moving loads is experimentally investigated. Analytical scrutiny is made on the shear fatigue behavior of RC beams subjected to moving loads based on strain path and time dependent fatigue constitutive models rooted in the multi-scale fixed four-way crack modeling of concrete. Moving load is found to cause dramatic reduction in fatigue life of RC beams as compared to that of the fixed pulsating load both in the experiment and analysis. The mechanism for the reduced fatigue life under moving loads in RC beams is discussed in contrast to that of RC slabs. A simplified relation for the prediction of fatigue life under moving load is proposed for practical use on the basis of standard shear fatigue design equation of JSCE code, used for fixed fatigue loading. The effect of randomness in the position of loading is examined and its implication for the reliability of current fatigue life assessment method of RC members is put forward. The applicability of the multi-scale computational platform is verified for the fatigue investigation of RC beams subjected to moving loads.

This paper has a significant engineering merit indicating the fatigue life of reinforced concrete beams under moving load is remarkably reduced by 2 to 3 orders from that of fixed point load. The research finding is supported by experimental as well as analytical study. The research is thorough and convincing. (Prof. S. Otani, Japan)