Image Analysis for Deformation Behaviors of RC Beams with Simulated Deteriorations under Moving Wheel Load

Abstract

In Japan, RC bridges slabs constructed during the high economic growth period are suffering from severe deteriorate due to fatigue. In cold and snowy regions, in addition to fatigue, the deterioration is accelerated and aggravated simultaneously by freeze-thaw cycles and water penetration simultaneously. Hence, in this study, aiming at investigating the deterioration due to this combined action, three RC beams were artificially damaged on the top surface by introducing expansion agents to simulate the freeze-thaw cycle damages beforehand, and then subjected to moving wheel load under either dry or wet condition. In the experiment, a scaling-off and a disintegration were observed on the top surface due to the existence of water. Besides, to facilitate the elucidation of the mechanisms, image analysis was employed to obtain the displacement distributions and strain distributions on the side surfaces of the specimens during the test. The results of image analysis clearly manifested that the water-induced deteriorations lead to a localized compressive strain on the upper part of the beams as well as detrimentally affected the propagation of the shear and bending cracks under the moving wheel load. In summary, the mechanical reasons of the remarkably shortened fatigue life of artificially damaged RC bridge slabs due to combined fatigue loads and water penetration were uncovered in this study taking advantage of the strengths of image analysis, which also provides reference and inspiration for further related studies.