反应谱兼容的时频非平稳地震动合成及其对结构非线性响应的影响

来源期刊:中南大学学报(自然科学版)2021年第3期

论文作者:王宁波 程顺 黄天立 李守文

文章页码:701 - 713

关键词:地震动模拟;时频非平稳;反应谱兼容;正交HHT方法;框架结构;非线性时程分析

Key words:simulation of earthquake ground motion; time-frequency non-stationarity; response spectra-compatible; orthogonal Hilbert-Huang transform; frame structure; nonlinear time history analysis

摘    要:基于演化谱和正交HHT方法合成地震动,通过迭代调整时变功率谱,使合成的地震动时程反应谱拟合目标反应谱,提出一种与目标反应谱兼容的时频非平稳地震动合成方法。以El Centro地震加速度时程南北分量作为种子地震动时程,设计与目标反应谱兼容的4组加速度时程,分别对7层和15层的2栋钢筋混凝土框架结构进行非线性时程分析,研究地震动时频非平稳特性对框架结构非线性响应的影响规律。研究结果表明:基于正交HHT方法合成的人工地震动不仅能更好地表征天然地震动的时频特性,而且其作用下的结构响应与天然地震动作用下的结构响应最接近;基于强度包络函数生成的人工地震动仅反映强度非平稳特性,而未反映频率非平稳特性,产生低估结构响应的问题,因此,采用合成人工地震动时程作为结构地震激励时,应考虑地震动的时频非平稳特性,以确保结构安全。

Abstract: Based on the simulation of the earthquake ground motions using the evolutionary spectra and the orthogonal HHT method, a simulation method was proposed for the target response spectra-compatible time-frequency non-stationary earthquake ground motions by iteratively adjusting the time-varying power spectrum to make the response spectrum of the simulated ground motions compatible with the target response spectrum. Taking the recorded El Centro earthquake accelerogram as the seed ground motion, four sets of earthquake ground motions for the same target response spectrum were obtained. Taking these four ground motions as the input, the non-linear time history analysis of two reinforced concrete frame structures with 7 and 15 floors were presented to investigate the influence of time-frequency non-stationary characteristics of ground motions on the nonlinear responses of frame structures. The results show that the synthesized artificial ground motion using the orthogonal HHT method can characterize the time-frequency characteristics of the real ground motion, and the structural nonlinear responses under its action are the closest to the ones in the real ground motion. The structural nonlinear responses in the artificial ground motions generated using the intensity envelope function may be underestimated due to that the strength non-stationary characteristics of the artificial ground motions are represented and the frequency non-stationary characteristics of the artificial ground motions are not represented. Therefore, the frequency non-stationary characteristics should be integrated into the simulation of the artificial ground motions. In this way, the structural nonlinear responses can be estimated reasonably and the safety of the structures can be ensured.

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