调整已有地震动拟和规范反应谱人造地震动方法比较

Comparison of Methods of Generation of Spectrum-compatible Artificial Earthquake through the Modification of Available Records

利用已有的地震记录调整得到拟和规范反应谱的人造地震动的方法越来越得到广泛的认可和应用。常用的方法包括比较粗略的比例调整法、比较精确的调整傅里叶幅值谱法、基于小波变换的调整方法和时域内叠加小波函数的方法等。本文详细介绍了各种谱拟和方法的原理以及实现过程中的难点;通过算例分析,对各种方法的优缺点进行了探讨。结果表明:当已有地震动反应谱与规范反应谱相差较大时,可先采用比例调整法粗调,然后再采用其他三种比较精确的方法继续进行调整;后三种方法都能快速地由实际地震动时程纪录得到拟和规范反应谱的人造地震动时程,并一定程度上保留原始时程的非平稳特征;相比之下,时域内叠加小波函数的方法精度最高,调整完后不用进行基线调整,是一种值得推荐的方法。

Spectrum compatible artificial earthquake through the modification of available records is widely accepted nowadays.There are four methods for the modification,including scaling method,modifying the Fourier amplitude,modification based on wavelet transform,modification through the adding of wavelet functions.In this paper,the theory and the difficulty in fulfillment are discussed in detail. Through the examples,the advantages and disadvantages of the four methods are discussed.When the discrepancy between the code response spectrum and response spectrum of the available record is large,the scaling method is adopted firstly,then one of the other three methods is utilized for the modification.The last three methods can all retain the temporal variations of the original accelerogram to a certain extent.But the method of adding wavelet is the best in precision.Moreover,the corresponding velocity and displacement time history can be obtained without baseline correction.The method of adding wavelet is recommended in practical use.