基于数字滤波技术拟合规范反应谱的地震动研究

Adjusting ground motion record time histories for fitting standard response spectrum based on digital filtering technology

在重要结构的抗震设计与分析中,常需要输入拟合设计反应谱的地震动时程。该研究提出一种基于数字滤波技术调整天然地震动记录拟合规范反应谱的方法,以设计谱频率控制点为中心确定频带数目与范围,针对各个频带利用无限冲激响应数字滤波器对强震动记录时程开展带通滤波,并以滤波所得频带分量为基函数重构地震动时程;以重构时程为种子时程,引入影响矩阵方法开展迭代计算逐步调整频带分量的幅值向量,直至时程反应谱与目标谱的拟合精度满足要求为止。选取3个不同类型设计谱为目标谱分别开展拟合计算,结果表明:该方法分解并重构的地震动时程与天然强震动记录在时域和频域的重合度均较高;可与不同设计谱实现高精度拟合,时程反应谱迭代收敛性好,且能较好地保留时程非平稳性,可为工程结构抗震设计与分析提供合适的地震输入。

In seismic design and analysis of important structures,it is often necessary to input ground motion record time histories to fit design response spectrum.Here,a method based on digital filtering technology to adjust natural ground motion records to fit standard response spectrum was proposed.The design spectrum frequency control point was taken as center to determine number and range of frequency bands.For each frequency band,an infinite impulse response digital filter was used to do band-pass filtering of strong seismic record time histories,and frequency band components obtained after filtering were taken as basis functions to reconstruct ground motion time histories.Taking the reconstructed time histories as the seed time histories,the influence matrix method was introduced to do iterative calculation,and gradually adjust the amplitude value vector of frequency band components until the fitting accuracy of time history response spectrum and target spectrum meets the needed requirements.Taking 3 different types design spectra as target spectra for fitting calculation.The results showed that coincidence degrees between the decomposed and reconstructed ground motion time histories and natural strong seismic motion records in time domain and frequency domain,respectively all are higher;the proposed method can realize high-precision fitting between its results and different design spectra;the time history response spectrum iteration convergence is good,and the time histories non-stationarity can be better kept,so the proposed method can provide appropriate seismic input for seismic design and analysis of engineering structures.