Hybrid Earthquake Loading Tests of Various Types of Base Isolation Bearings
Under a joint research program between Kyoto University and the Hanshin Expressway Public Corporation, five isolation bearings of different damping mechanisms were tested under identical test conditions in order to evaluate their suitability and applicability to different types of bridges. The isolation bearings, including the lead-rubber bearing, two types of high-damping rubber bearings, sliding rubber bearing, and a conventional rubber bearing were tested under cyclic loading and hybrid earthquake (pseudo-dynamic) test methods. In addition to the fundamental cyclic load-deformation behavior, earthquake and resonant response behavior of the five isolation bearings were obtained. From the test results, equivalent damping ratios are evaluated based on the usual cyclic loading tests as well as from earthquake response of equivalent linear elastic models. In addition, the effectiveness of isolation is evaluated based on acceleration and displacement amplifications using earthquake response results obtained from the hybrid earthquake loading tests. In order to evaluate the effect of initial first-cycle stiffness of rubber bearings on the earthquake response, a second identical specimen of each type of isolation bearings was tested for its virgin earthquake response behavior.
KeywordsSeismic Isolation Base Isolation Rubber Bearing Earthquake Response Isolation Device
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