Damping Identification of Bridges Under Nonstationary Ambient Vibration

本研究着重于使用非平稳的环境振动数据来识别桥梁的阻尼比。我们通常使用基于输入信号的静态白噪声假设的运行模态分析(OMA)来识别使用中的桥梁的阻尼比。然而,大多数桥梁在使用时通常会受到非平稳激励,而违反这种基本假设会导致阻尼识别的不确定性。为了处理非平稳性,根据测量的响应来计算幅度调制函数,以消除由非平稳输入引起的整体趋势。采用自然激励技术(NExT)-特征系统实现算法(ERA)估算平稳过程中的阻尼比。为了提高基于OMA的阻尼估计的准确性,在提取的平稳过程和非平稳数据之间进行比较分析,以评估消除非平稳性的效果。在信号平稳化后,第一竖向模态的阻尼比的平均值和标准偏差会减小。

This research focuses on identifying the damping ratio of bridges using nonstationary ambient vibration data. The damping ratios of bridges in service have generally been identified using operational modal analysis （OMA） based on a stationary white noise assumption for input signals. However, most bridges are generally subjected to nonstationary excitations while in service, and this violation of the basic assumption can lead to uncertainties in damping identification. To deal with nonstationarity, an amplitude-modulating function was calculated from measured responses to eliminate global trends caused by nonstationary input. A natural excitation technique （NExT）-eigensystem realization algorithm （ERA） was applied to estimate the damping ratio for a stationarized process. To improve the accuracy of OMA-based damping estimates, a comparative analysis was performed between an extracted stationary process and nonstationary data to assess the effect of eliminating nonstationarity. The mean value and standard deviation of the damping ratio for the first vertical mode decreased after signal stationarization.