Evaluation of Fatigue Damage in RC Slabs Considering Water Infiltration by Means of 3D AE and Elastic Wave Tomography

摘要

To maintain civil engineering infrastructures reasonably, proper maintenance programs shall be implemented before remarkable damage/deterioration. As for RC slabs of road bridges, an evolutional process of fatigue damage shall be studied to establish the proper maintenance program. The authors have enthusiastically studied the mechanism of fatigue failure of the RC slabs; however, there is still space to clarify internal fatigue damage progress in consideration of water infiltration. In the study, to know the fatigue failure mechanism of RC decks in consideration of water infiltration, a wheel loading test of the RC slab filled with water on the surface is conducted systematically. Numerous numbers of repetition of the wheel load are conducted by several loads' step and after each designated cycle e.g., 100, 200 and 250 k cycles, the specimen is subject to static load with monitoring AE activity. With using AE activity namely AE sources located, 3D AE tomography is implemented to identify the damage with elastic wave velocity distributions (tomogram). Based on the tomograms obtained each loads' step, failure mechanisms in consideration of water infiltration is discussed in comparison with the cases without infiltration. Through the study, very unique failure progress, being different from dry condition, which expands from first-introduced cracks comes to light.