The monitored seismic response data provides useful insight into the dynamic characteristics of cable-stayed bridges during an earthquake shaking. However, the unavailable earthquake input data, as is the case for most cable-stayed bridges, would prevent the system identification using the during-shaking structural response. This study proposes to employ the post-shaking structural response only for system identification of cable-stayed bridges. A 1/20 scaled cable-stayed bridge model under longitudinal shake table accelerations is utilized as a case study for validation. It reveals that the post-shaking seismic response of the scaled cable-stayed bridge is considerably significant. Using the during-shaking data (including the earthquake input) or the post-shaking data (without earthquake input) would yield similar system identification results regardless of the seismic system of the bridge or the characteristics of the input ground motions. The sliding bearings, with pronounced nonlinearity, lead to the variable system identification results of the first sliding mode of the girder but exert a limited influence on the dynamic characteristics of the higher modes. When the ground motions are unknown, the shaking end can be identified within the transition from the nonstationary to stationary response based on the time–frequency analysis of monitored structural responses.

中文翻译：

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利用震后监测数据对地震激励下的斜拉桥进行系统识别


监测到的地震响应数据为了解地震震动期间斜拉桥的动态特性提供了有用的见解。然而，与大多数斜拉桥一样，不可用的地震输入数据将阻止使用震动期间的结构响应进行系统识别。本研究建议仅将震后结构响应用于斜拉桥的系统识别。采用纵向振动台加速度下的 1/20 比例斜拉桥模型作为验证实例。它揭示了缩放斜拉桥的震后地震响应相当显着。无论桥梁的地震系统或输入地震的特征如何，使用震动期间数据（包括地震输入）或震后数据（无地震输入）都会产生类似的系统识别结果。具有明显非线性的滑动支座导致梁的第一滑模系统识别结果可变，但对更高模态的动力学特性的影响有限。当地震动未知时，可以根据监测结构响应的时频分析，在从非平稳响应到平稳响应的过渡中识别振荡端。