大型桥梁模态参数识别的一种方法

提出一种综合运用经验模态分解(EMD)与随机减量技术(RDT)来识别大型桥梁模态参数的方法。首先利用EMD将桥梁在环境激励下的非平稳响应分解成一系列准平稳的本征模函数(IMF)分量,然后用RDT从中提取自由衰减响应,最后将该自由响应表达为一般解析形式,综合运用参数识别理论、最优估计理论识别出桥梁结构的多阶模态参数。利用南京长江大桥实测动力响应识别该桥的模态参数,并将识别结果与有限元分析结果及有关实测值进行比较,表明该方法具有很好的识别精度,适用于大型桥梁的模态参数识别。

A METHOD OF MODAL PARAMETER IDENTIFICATION FOR LARGE BRIDGES

A method to identify modal parameters for large bridges is presented using empirical mode decomposition (EMD) and random decrement technique (RDT) simultaneously. Firstly, the non-stationary response of the bridge under ambient excitation is decomposed into a series of quasi-stationary intrinsic mode functions (IMFs) by carrying out EMD. Secondly, RDT is applied to certain IMFs to obtain the free responses. Finally, the free vibration signals are expressed in analytic forms in which modal parameters of the bridge are included. Parameter identification theories and optimum estimate theories are used in obtaining multiple modal parameters of the bridge. The modal parameters of the Nanjing Yangtze River Bridge identified from the measured response by the method presented in the paper are compared with those provided by finite element analysis and related measured values. The results demonstrate that the method is effective,robust,and promising to modal parameter identification for large bridges.