The accurate estimation of natural frequencies and damping ratios is critical for civil structures. In this article, a method based on short-time narrow-banded mode decomposition is proposed to analyze the modal parameters of civil structures. In this approach, short-time narrow-banded mode decomposition is applied to identify time-varying structures with free vibration responses. On the contrary, by analysis of the weighting factors α and β, short-time narrow-banded mode decomposition is improved to estimate the parameter of time-invariant systems. In the case of enhanced short-time narrow-banded mode decomposition, the original short-time narrow-banded mode decomposition approach is modified in two ways. First, the instantaneous frequency term of the objective function is removed, and one weighting factor remains, that is, α in the objective function. Second, a technique is provided to automatically detect the optimum value of α. Two numerical examples, that is, a three-degree-of-freedom time-variant system and a simple model of the Lysefjord bridge are provided. In addition, an experiment with a real-life pedestrian bridge located at Tufts University, United States, is used to demonstrate the applicability of the proposed method. The analysis results indicate that the proposed method can easily identify high-quality natural frequencies and damping ratios.

中文翻译：

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基于短时窄带模态分解的结构模态参数识别

自然频率和阻尼比的准确估计对于土木结构至关重要。本文提出了一种基于短时窄带模态分解的土木结构模态参数分析方法。在这种方法中，应用短时窄带模式分解来识别具有自由振动响应的时变结构。相反，通过对权重因子α和β的分析，改进了短时窄带模式分解来估计时不变系统的参数。在增强短时窄带模式分解的情况下，对原有的短时窄带模式分解方法进行了两种修改。首先，去除目标函数的瞬时频率项，保留一个权重因子，即 目标函数中的α。其次，提供了一种技术来自动检测 α 的最佳值。提供了两个数值例子，即一个三自由度时变系统和一个 Lysefjord 桥的简单模型。此外，通过位于美国塔夫茨大学的真实人行天桥的实验来证明所提出方法的适用性。分析结果表明，所提出的方法可以轻松识别高质量的固有频率和阻尼比。美国，用于证明所提出方法的适用性。分析结果表明，所提出的方法可以轻松识别高质量的固有频率和阻尼比。美国，用于证明所提出方法的适用性。分析结果表明，所提出的方法可以轻松识别高质量的固有频率和阻尼比。