Abstract
Performance of base-isolated bridges is evaluated using the observed records of the main shock as well as after shocks during 1995 Kobe earthquake. In the first half of the paper, the motion of the superstructure supported by lead-rubber bearings, is shown to be approximated by the single-degree-of-freedom system where the superstructure is assumed to be rigid body. In the second half of the paper, the stiffness and damping coefficients of superstructure identified from observed records are compared with those calculated through the equivalent-linearization using the cyclic loading tests performed prior to installation. The comparison reveals good agreement between the design values and observed dynamic characteristics and the performance of base-isolation bearing is confirmed.
