《Earthquake Engineering and Structural Dynamics》杂志刊登“利用强震记录识别结构模态响应”

作者：S. F. Ghahari,  F. Abazarsa,  M. A. Ghannad, E. Taciroglu

刊物：《Earthquake Engineering and Structural Dynamics》，2013年，42卷第8期，

     1221—1242页

关键词：盲系统识别；模态识别；仅输出技术；强地震动；土-结构作用；空间时域分布

摘要：结构的动力特性频率、阵型和阻尼比是抗震设计的关键参数。这些参数可以通过场地测量获得，并将其应用于模态确认和安全评价。许多系统识别方法需要测量荷载输入和结构响应，然而，真实的荷载输入是很难测得的。例如，当土—结构作用不容忽视时，那么自由场运动和测得基础响应都将不能被假定为输入。即使不考虑土-结构相互作用，在许多情况下，基础响应也是测不到的（即便测得，也是低信噪比响应）。更差的是，现行的仅输出方法仅限于自由场数据或低平稳环境激励。然而，大部分土建结构的动力特性是依赖于振幅的。因此，低振幅响应参数识别与那些强震激励不匹配，但强震激励却与抗震设计有关。本文提出了一种仅通过地震响应信号来获得结构动力参数的新识别方法。该方法有两个特点：首先利用结构空间时域分布响应信号对经典结构形式和模态坐标信号进行盲识别；其次在线性系统条件下，利用模态坐标之间的交叉项来识别系统的固有频率和阻尼比。本文最后利用模拟数据检验了该方法，并应用实际数据表明了该方法的实用性。

Response-only modal identification of structures using strong motion data

Authors: S. F. Ghahari, F. Abazarsa,  M. A. Ghannad, E. Taciroglu

Journal: Earthquake Engineering and Structural Dynamics, Volume 42, Issue 8, pages1221-1242, 10July2013

Key words: blind system identification; modal identification; output-only techniques; strong ground motions; soil–structure interaction; spatial time-frequency distributions

Abstract: Dynamic characteristics of structures — viz. natural frequencies, damping ratios, and mode shapes — are central to earthquake-resistant design. These values identified from field measurements are useful for model validation and health-monitoring. Most system identification methods require input excitations motions to be measured and the structural response; however, the true input motions are seldom recordable. For example, when soil–structure interaction effects are non-negligible, neither the free-field motions nor the recorded responses of the foundations may be assumed as ‘input’. Even in the absence of soil–structure interaction, in many instances, the foundation responses are not recorded (or are recorded with a low signal-to-noise ratio). Unfortunately, existing output-only methods are limited to free vibration data, or weak stationary ambient excitations. However, it is well-known that the dynamic characteristics of most civil structures are amplitude-dependent; thus, parameters identified from low-amplitude responses do not match well with those from strong excitations, which arguably are more pertinent to seismic design. In this study, we present a new identification method through which a structure's dynamic characteristics can be extracted using only seismic response (output) signals. In this method: first, the response signals’ spatial time-frequency distributions are used for blindly identifying the classical mode shapes and the modal coordinate signals. Second, cross-relations among the modal coordinates are employed to determine the system's natural frequencies and damping ratios on the premise of linear behavior for the system. We use simulated (but realistic) data to verify the method, and also apply it to a real-life data set to demonstrate its utility. 

原文链接：http://onlinelibrary.wiley.com/doi/10.1002/eqe.2268/abstract