Study on Dynamic Damaging Properties of Ground Motions to RC Structures by Shaking Table Tests

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Dynamic damaging properties of ground motions to structures must be evaluated by both peak value and cyclic effect during earthquakes. In this study, damaging properties of ground motions to RC structures are assessed by analytical study and shaking table tests of RC frame specimens under simulated input waves with different characteristics.In analytical study of observed ground motions, damaging characteristics are estimated based on concept of inergy response, such as total input energy or energy input process of ground motions. It is found that near field ground motions tend to bring very large input energy by initial 1 or 2 cycles, then such input energy causes large response of structures. And oceanic plate ground motions tend to bring input energy with relatively long duration time and causes cumulative damages.In shaking table tests, response behaviors of RC frame specimens during earthquakes with different damaging properties are investigated. Test specimens, that consist of 4 columns, rigid beams and top weight, are 1 story 1 span RC frame with moment yielding mechanism. In this experiment, input waves compensated with braced specimens that is already loaded, are used to avoid power reduction cased by interaction effects. By this method, input waves almost corresponding to expected ground motions are observed on the shaking table. And it is found that maximum response inertial force is about 10 percent larger than static restoring force, and that hysteresis loop by near field ground motions is relatively smaller than that of oceanic plate ground motions.