A Comparative Study of U.S.-Japan Seismic Design of Highway Bridges: II. Shake-Table Model Tests

As part of a comparative study on the United States' and Japan's seismic design of highway bridges, three scale models of a reinforced-concrete bridge column are tested on a shake table for their seismic performance. Three specimens, one based on the ductility design method (U.S.) and the others on the working stress design method (Japan), are subjected to a set of successive earthquake ground motions with varying intensities. All three specimens showed good performance; however, the specimen of ductility design experienced less damage than those of working stress design. Analysis of test results showed that structural degradation in each column closely correlates with decrease in the transverse stiffness, increase in the hysteretic energy dissipation, and increase in the vibration period, of the column. Two damage indices, based respectively on effective flexibility and weighted cumulative hysteretic energy, are used to indicate the progression of structural degradation in a reinforced-concrete bridge column subjected to successive earthquake ground motions.