Damage Estimation of Buckle Plate Slab Under Fatigue Test by Elastic Wave Method

Abstract

Tokyo Metropolitan Government has drawn up a long-term bridge strategy for long time use of existing bridges. Especially, Kiyosu bridge in Tokyo has been designated as a nationally important cultural property, maintenance of this bridge is in great demand. Buckle plate (BP) slab has been adopted for this bridge. BP slab consists of steel plate and concrete, its characteristic is that steel plate and concrete are not connected structurally. The adopting of BP slab is rare in highway bridges in Japan. Since there is little information about fatigue durability on BP slab, fracture mechanisms and fatigue durability on BP slab have not been clarified yet. In addition, it is important to draw up a maintenance strategy of BP slab. In this study, wheel load running test was conducted to real-size BP slab specimen to investigate fatigue durability and fracture mechanisms. In the experiment, Acoustic Emission (AE) monitoring and elastic wave method were applied to estimate concrete damage in BP slab. As a result, deterioration process in BP slab of fatigue test is discussed based on deflection, AE source location and elastic wave velocity of the specimen. In the AE monitoring, AE sources were localized at bottom of the specimen in early cycles of fatigue test because delamination occurred at between concrete and steel plate, and then AE signals due to punching shear cracks were detected with increasing of loading cycle. As for results of the elastic wave method, elastic wave velocity in concrete decreased with increasing of loading cycle, damage degree could be estimated by elastic wave method. Therefore, AE method and elastic wave method are demonstrated as one of the suitable tools for maintenance of the BP slab.