满足数据同一性的强震动记录去噪滤波后处理输出方法

A POST PROCESSING METHOD OF STRONG MOTION RECORD FILTERING SATISFYING THE COMPATIBILITY

  • 摘要: 强震动记录的工程应用需求十分广泛,国内外关于其去噪滤波完成后的去补零后处理输出方法的相关研究开展较少,我国在这方面则鲜见文献报道。针对这一问题,该文以典型强震动记录示例阐明了直接积分去补零加速度时程导致位移时程基线漂移的物理原因;提出了一种既能解决此基线偏移现象又可以满足输出数据同一性的去补零后处理输出方法,给出了完整的处理流程;针对流程中的关键环节——位移时程基线校正,通过比较2阶~8阶多项式函数拟合基线与线性函数拟合基线之间的决定系数,建议使用6阶多项式作为位移时程基线拟合的优选函数;针对流程中的另一关键环节——时程尾端渐变趋零处理,推导给出了一种隐式处理方法,并验证了其可仅对加速度时程进行处理即可自动实现积分得到的速度和位移时程尾端渐变趋零效果;选用芦山地震中的112个强震动记录作为数据集,通过比较位移时程以及与其相关的PGD和drms值与去补零直接输出结果的一致性,验证了新流程的有效性;同时也比较了多个常用的IM参数值的一致性,验证了新流程可确保常用IM参数计算的准确性。此项工作将有助于指导和规范强震动记录经滤波处理后的合理输出和使用,为记录使用者提供有益的帮助。

     

    Abstract: Strong motion records are widely applied in engineering at present. However, there are few studies in the world focusing on the data output after the records processed by high-pass acausal filtering, and there is no literature reporting this issue in China yet. In this study, a case study of typical record is illustrated on the physics of baseline drift of displacement time series resulted from integrating pad-stripped accelerogram directly. Then a new procedure of post-processing output for the pad-stripped strong motion records is proposed, which has advantages that it could correct the baseline of displacement time series and output the compatible data. The six-order polynomial is suggested to be an optimal function used for fitting the baseline of displacement time series by comparing the decision coefficients between the baselines fitted by 2-8 orders polynomial functions and that fitted by linear function. An implicit method tapering the end of time series is developed, which has advantages that it can achieve automatically tapering the end of velocity and displacement time series when making an integration of acceleration time series. 112 strong motion records collected in Lushan earthquake in 2013 are used to constitute a comparison of their displacement time series, PGD and drms values between the derived data from the output data of proposed procedure and the pad-stripped data. Moreover, some other acceleration-related commonly-used IM parameters are also involved in the comparison. The results show that the procedure proposed in this study is effective and accurate in post-processing output data. It could help to guide and normalize the data users to have an appropriate way for outputting strong motion records after filtering processing.

     

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