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

地震动对结构的动力损伤特性必须同时考虑地震时的峰值效应和周期效应。本文通过钢筋混凝土框架试件在不同特征的模拟输入波作用下的分析研究和振动台试验，评估了地震动对钢筋混凝土结构的损伤特性。在对观测到的地震动的分析研究中，基于无能响应的概念来估计损伤特征，如总输入能量或地震动能量输入过程。研究发现，近场地震动在最初的1~2个周期内往往会带来很大的输入能量，然后这种输入能量会引起结构的大响应。在振动台试验中，研究了钢筋混凝土框架试件在不同损伤性质地震作用下的反应特性。试件为1层1跨带弯矩屈服机制的钢筋混凝土框架，由4根柱、刚性梁和顶重组成。在本实验中，输入的波用已加载的支撑试件补偿，以避免因相互作用而导致的功率降低。通过这种方法，在振动台上观察到了与预期地面运动几乎对应的输入波。结果表明，最大响应惯性力比静力恢复力大10%左右，近场地震动滞回环比大洋板块地震动的滞回曲线小得多。

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.