高拱坝泄流激励下基于频域法的工作模态参数识别

OPERATIONAL MODAL PARAMETER IDENTIFICATION OF HIGH ARCH DAM UNDER FLOOD DISCHARGE EXCITATION BASED ON FREQUENCY DOMAIN DECOMPOSITION METHOD

水工结构的模态参数是评估在役水工结构运行状态的指标之一,水工结构运行状态健康诊断的核心技术之一就是如何通过各种技术手段获取结构的模态参数指标。研究高拱坝在泄流激励荷载作用下,仅利用结构输出响应识别结构工作模态参数。首先,对高拱坝泄洪诱发振动的激振荷载特性进行了研究;其次,分别建立了以典型水流脉动荷载和白噪声荷载作为输入激励的悬臂梁动力响应数值模型,仅利用输出响应识别了悬臂梁的模态参数,并对识别结果进行了对比分析,论证了以水流脉动荷载作为未知输入仅利用流激振动响应进行结构工作模态参数识别的可行性。最后以二滩拱坝泄洪振动原型观测数据为基础,对二滩拱坝的泄洪工作模态参数进行了识别并评估了该拱坝的泄洪动力性态。

The characteristic of exciting load which induces the vibration of high arch dam under flood discharge is studied. Then, a numerical dynamic response cantilever beam model which is excited by either flood fluctuating load or white noise load is set up, and the modal parameters of the cantilever beam model are identified with output response data alone. The effectiveness of the method is demonstrated according to the comparison between the results of the two numerical models. Based on the observed vibration data on the prototype of Ertan arch dam under the condition of flood discharge, the operational modal parameters of Ertan arch dam are identified and its dynamic characteristics are evaluated.