溪洛渡拱坝模态参数识别

随着一系列高拱坝在西南地区兴建，坝体的健康状况及其真实的抗震性能成为近年来研究的热点。模态参数反映坝体结构的动态特性，可用于评估坝体的健康状况及更新坝体抗震分析有限元模型。本文基于永善县两次地震记录和环境激励数据，分别采用带外源输入的自回归（ARX）模型、随机子空间法（SSI）和频域分解法（FDD），识别溪洛渡拱坝的模态参数。结果显示，在相同工况下，不同算法识别结果的差异较小；当水位一致时，基于环境激励数据识别结果与基于地震记录识别结果基本一致，当库水水位从566 m变化到598 m时，坝体第一阶自振频率从1.63 Hz减小到1.51 Hz；地震前后识别结果基本一致，表明溪洛渡拱坝在经历两次地震作用后，坝体振动特性不变，坝体处于正常运行状态。

Modal parameter identification for Xiluodu arch dam

With a train of high arch dams built in Southwest China, the health of dam structures and their anti-seismic properties have become a hot issue in recent years. Modal parameters reflect the dynamic characteristics of dam structures and are applicable to evaluating dam health status and updating the finite element models for arch dam anti-seismic analysis. This paper presents a study on the identification of modal parameters for Xiluodu arch dam using the ARX, SSI and FDD procedures separately, based on two earthquake recorders located in Yongshan County and ambient vibration test data. The results show the modal parameters identified using ambient vibration tests agree with those identified using the recorded data. When the reservoir stage varies from 566 m to 598 m, the fundamental vibration frequency of this dam is lowered from 1.63 Hz to 1.51 Hz. And similar frequencies identified before and after the earthquakes indicate that the dam is in the normal operation condition.