基于Hilbert-Huang变换的框架结构非线性地震响应分析

THE NONLINEAR ANALYSES OF FRAME SEISMIC RESPONSE BASED ON HILBERT-HUANG TRANSFORM

利用HHT方法分析多自由度框架结构地震作用下的动力响应.分析结果显示:由于多自由度结构地震响应所含频率成分复杂,用HHT方法难以直接得到多自由度结构地震作用下的非线性时变特征.考虑到多自由度结构大多以低阶振型为主,本文以结构一阶振型为例,引入等效单自由度来分析多自由度结构的动力特征.结果表明,利用等效单自由度结构的瞬时卓越频率可以得到多自由度结构刚度的时变动力特征.

The seismic response of MDOF frame was analyzed by Hilbert-Huang Transform. The results showed that the nonlinear time variant characteristics of MDOF frame under seismic load was hard to obtain by HHT, because of the complicated frequencies in the seismic response of MDOF frame. Because the vibration of MDOF frame is based on the low order mode shape, in this paper, considering the first order mode shape, the dynamic characteristic of MDOF system was analyzed by introducing the equivalent single-degree-of-freedom system. The results showed that the time variant dynamic characteristic of MDOF frame could be obtained by the instant excel-lence frequency of equivalent single-degree-of-freedom.