环境激励下泄流结构的模态参数辨识研究

Studies on Modal Parameter Identification of Discharge Structure under Ambient Excitation

水工结构在泄流激励作用下易产生剧烈振动甚至会因振动而引起结构自身破坏,为研究坝体在泄流工作状态下的振动特性,需准确地辨识出结构的模态参数指标。为此,以三峡枢纽工程#5溢流坝段为例,在坝体泄流作用下对其进行原型振动响应信号采集,根据测出的响应时程,分别采用ERA法和HHT法对结构进行模态参数辨识,并将辨识出的频率与有限元模态计算的结果进行比较。结果表明,ERA法和HHT法均具有识别结构密频的能力,两种方法提取出的频率值与有限元仿真结果吻合很好,但HHT法在识别阶数和精度方面均优于ERA法,更能全面、准确地反映结构的动力特性。

Under the effect of flood discharge excitation,hydraulic structure can produce violent vibration easily and even be damaged.In order to study the dam vibration characteristics under discharge working condition,structural modal parameters should be identified accurately.Thus,5th overflow section of the Three Gorges project was selected to get the prototype vibration response signal acquisition under the effect of flood discharge excitation.According to the measured response signal,ERA method and HHT method were used to identify structural modal parameters.And then the frequency by identification was compared with the result of finite element modal calculation.The results show that both ERA method and HHT method have the ability to recognize the dense frequency of structure.Two extracted frequency values are both in good agreement with the FEM simulation results.But HHT method is better than ERA in precision and order identification,and it can reflect the structural dynamic characteristics more comprehensively and accurately.