Abstract
To mitigate earthquake damage to highway bridges, many laminated rubber bearings were installed in Japan following the 1995 Great Hanshin-Awaji Earthquake. Recently, deterioration of these rubber bearings, which affects the seismic performance of the bridges, has been reported. However, an accurate assessment of damage to rubber bearings (for early warning) is difficult because of a rubber covering that interferes with checking inside.
This study evaluates the acoustic emission (AE) method, a non-destructive test (NDT), for evaluating damage to these rubber bearings. Verification of the method was conducted by laboratory tests as well as field measurements. The AE activities and the parameters of the deteriorated bearings were compared with new ones. Many AE hits and a large amount of AE energy were observed from the deteriorated rubber bearings through the laboratory tests and the field measurements. On the other hand, few AE activities were observed from new bearings. Internal damage to deteriorated bearings was verified with microscopic observation of the cut plane after the loading tests. The results showed that internal damage to these rubber bearings can be accurately estimated using AE.
