To validate the seismic retrofitting of buildings quantitatively, we observed microtremors in the Uji campus buildings at Kyoto University. We compared the dynamic characteristics derived from the resonant frequency of microtremors in a five-story steel-frame structure and a three-story reinforced-concrete (RC) building before and after retrofitting. We calculated the weight of the building from the retrofitting design plan and constructed a numerical model of the structure by estimating the building stiffness that fits the resonant frequency. Assuming the characteristics of the restoring force for each story of the numerical model from previous studies, we calculated the non-linear response of the building to the strong motions predicted for earthquakes occurring at the Obaku fault system that runs right in front of the Uji campus. We compared the response of the numerical models constructed before and after retrofitting to verify the effects of the seismic retrofitting. We found that the proposed method of dynamic response model construction using microtremor observations is effective when the reinforcement members are rigidly fixed to the existing structure, as is the case for RC buildings.

中文翻译：

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基于观测微震的抗震加固效果定量评价

为了定量验证建筑物的抗震改造，我们观察了京都大学宇治校区建筑物的微震。我们比较了五层钢框架结构和三层钢筋混凝土（RC）建筑改造前后微震共振频率的动态特性。我们根据改造设计计划计算了建筑物的重量，并通过估计适合共振频率的建筑刚度来构建结构的数值模型。假设以前研究的数值模型的每个楼层的恢复力的特征，我们计算了建筑物对预测的强烈运动的非线性响应，这些地震发生在宇治校区前面的 Obaku 断层系统中. 我们比较了改造前后构建的数值模型的响应，以验证地震改造的效果。我们发现，当钢筋构件刚性固定在现有结构上时，使用微震观测的动态响应模型构建方法是有效的，就像 RC 建筑物一样。