Earthquake damage detection in the Imperial County Services Building III: Analysis of wave travel times via impulse response functions
Earthquake damage detection in the Imperial County Services Building III: Analysis of wave travel times via impulse response functions
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DOI：
10.1016/j.soildyn.2007.07.001
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发表时间：
2008-05
影响因子：
4
通讯作者：
M. Todorovska;M. Trifunac
中科院分区：
文献类型：
--
作者：
M. Todorovska;M. Trifunac
大多数结构健康监测方法都是基于检测结构的整体特征--模态特性的变化，对局部损伤不敏感。另一方面，结构选定部分之间的波传播时间是局部特征，可能对局部损伤更敏感。本文探讨了一种基于波传播时间变化的结构健康监测方法，该方法利用1979年帝国谷地震的强震数据，记录在被地震严重破坏的原帝国郡服务(ICS)大楼内。根据记录的水平地震响应在三个时间窗口内计算的脉冲响应函数来测量波传播时间-根据对记录响应的新颖性的分析，确定最大幅度响应之前、期间和之后。结果表明，初始刚度的空间分布符合设计特征，主要损伤后的刚度减小与观测到的损伤的空间分布一致。行程时间也被用来估计结构F1的基本固定基频(假设建筑物变形为剪切梁)，以及它在这次地震中的变化。这些估计与以前对地震期间土壤-结构系统频率fsys的估计(f1和lt；fsys预期来自土壤-结构相互作用研究)以及其他频率估计(f1来自ETABS模型，fsys来自环境振动试验，以及“瞬时”f1来自高频脉冲传播)是一致的。
The majority of structural health monitoring methods are based on detecting changes in the modal properties, which are global characteristics of the structure, and are not sensitive to local damage. Wave travel times between selected sections of a structure, on the other hand, are local characteristics, and are potentially more sensitive to local damage. In this paper, a structural health monitoring method based on changes in wave travel times is explored using strong motion data from the Imperial Valley Earthquake of 1979 recorded in the former Imperial County Services (ICS) Building, severely damaged by this earthquake. Wave travel times are measured from impulse response functions computed from the recorded horizontal seismic response in three time windows—before, during, and after the largest amplitude response, as determined from previous studies of this building, based on analysis of novelties in the recorded response. The results suggest initial spatial distribution of stiffness consistent with the design characteristics, and reduction of stiffness following the major damage consistent with the spatial distribution of the observed damage. The travel times were also used to estimate the fundamental fixed-base frequency of the structure f1(assuming the building deformed as a shear beam), and its changes during this earthquake. These estimates are consistent with previous estimates of the soil–structure system frequency, fsys, during the earthquakes (f1<fsysas expected from soil–structure interaction studies), and with other estimates of frequency (f1from ETABS models, and fsysfrom ambient vibration tests, and “instantaneous”f1from high-frequency pulse propagation).