Abstract

The role of signal-based nonlinear system identification methods for the rapid post-earthquake damage assessment of reinforced concrete (RC) bridge piers is explored. Experimental data from the shaking table tests of six RC columns with and without corrosion damage are used as benchmark data. The specimens are excited under three different ground motions with different time-series characteristics, structural detailing, and corrosion levels. The proposed system identification methods make use of accelerations alone (but not displacements as these are costly in-situ) to estimate the instantaneous frequency. The Wigner-Ville distribution and Hilbert transform are utilised due to their high resolution in both time and frequency domains. A combination of modal filtering and thresholding, using instantaneous amplitudes, is employed to attenuate the unreliable spikes in the Hilbert transform’s instantaneous frequency estimates. Their performance is benchmarked against a moving linear regression and standard white-noise tests. The comparison of the experimental results and time-frequency analysis indicates that the Wigner-Ville distribution and the Hilbert transform can produce reliable rapid damage detection when the response amplitude is large. The Wigner-Ville distribution has better robustness and higher resolution. The robustness of the more computationally efficient Hilbert transform can be significantly improved by the introduction of modal filtering and thresholding.

摘要

探讨了基于信号的非线性系统识别方法在钢筋混凝土 (RC) 桥墩的快速震后损坏评估中的作用。六根钢筋混凝土柱有无腐蚀损伤的振动台试验实验数据用作基准数据。试样在具有不同时间序列特征、结构细节和腐蚀水平的三种不同地面运动下被激发。所提出的系统识别方法仅使用加速度（但不使用位移，因为这些在原地成本高昂）来估计瞬时频率。Wigner-Ville 分布和 Hilbert 变换因其在时域和频域中的高分辨率而被使用。模态滤波和阈值的组合，使用瞬时幅度，用于衰减希尔伯特变换的瞬时频率估计中的不可靠尖峰。它们的性能以移动线性回归和标准白噪声测试为基准。实验结果与时频分析对比表明，Wigner-Ville分布和Hilbert变换在响应幅度较大时可以产生可靠的快速损伤检测。Wigner-Ville 分布具有更好的鲁棒性和更高的分辨率。通过引入模态滤波和阈值，可以显着提高计算效率更高的希尔伯特变换的鲁棒性。实验结果与时频分析对比表明，Wigner-Ville分布和Hilbert变换在响应幅度较大时可以产生可靠的快速损伤检测。Wigner-Ville 分布具有更好的鲁棒性和更高的分辨率。通过引入模态滤波和阈值，可以显着提高计算效率更高的希尔伯特变换的鲁棒性。实验结果与时频分析对比表明，Wigner-Ville分布和Hilbert变换在响应幅度较大时可以产生可靠的快速损伤检测。Wigner-Ville 分布具有更好的鲁棒性和更高的分辨率。通过引入模态滤波和阈值，可以显着提高计算效率更高的希尔伯特变换的鲁棒性。