基于稳态简谐激励的人行桥模态参数识别

发布时间：2019-05-29 14:26

【摘要】：为了探究稳态激振现场试验方法在人行桥模态参数识别中的可行性,通过数值仿真分析和现场试验,研究了基于稳态激振的人行桥模态参数识别。该方法首先通过单点简谐激励获得结构稳态响应的频响函数(FRF),然后对实测频响函数按单模态或多模态叠加形式进行最小二乘曲线拟合得到结构的固有频率、阻尼比、模态振型和模态质量。以一频率密集分布的多点弹性支撑梁为数值算例,分析了激振器激振质量、频率间隔、激振次数、多模态参与和噪声对识别结果的影响。采用该方法识别了一座双层分离桥面曲线人行桥第1阶侧弯模态的频率、模态质量及阻尼比,为该桥的人致振动分析及减振设计提供了有效手段。结果表明:激振质量会改变结构固有模态参数,因此在满足激振条件下激振质量应尽可能小;选择合适的激振带宽和较小的激振频率间隔能获得更可靠的结果;人行桥现场稳态激振试验识别的频率和阻尼比与自由振动识别结果基本相符,识别的模态质量与有限元计算结果相符,说明该方法可行。
[Abstract]:In order to study the feasibility of the steady-state excitation field test method in the identification of the modal parameters of the pedestrian bridge, the modal parameter identification of the pedestrian bridge based on the steady-state excitation is studied by numerical simulation and on-site test. The method comprises the following steps of: firstly, obtaining a frequency response function (FRF) of a structure steady-state response through a single-point simple harmonic excitation, and then performing least-square curve fitting on the measured frequency response function in a single mode or a multi-mode superposition form to obtain the natural frequency, the damping ratio, the mode vibration mode and the modal quality of the structure. The influence of excitation quality, frequency interval, number of excitation, multi-mode participation and noise on the recognition result of vibration exciter is analyzed by using a multi-point elastic support beam with a frequency-intensive distribution as a numerical example. The frequency, modal mass and damping ratio of the first-order lateral bending mode of a double-deck separated bridge deck curve pedestrian bridge are identified by the method, and an effective means is provided for the human-induced vibration analysis and the vibration-damping design of the bridge. The results show that the excitation mass can change the intrinsic mode parameters of the structure, so that the excitation mass should be as small as possible under the excitation condition; the appropriate excitation bandwidth and the smaller excitation frequency interval can be selected to obtain more reliable results; The frequency and damping ratio of the on-site steady-state excitation test of the pedestrian bridge are basically in accordance with the results of the free vibration identification, and the identified modal quality is in accordance with the finite element calculation results, and the method is proved to be feasible.
【作者单位】：湖南大学风工程与桥梁工程湖南省重点实验室;
【基金】：国家自然科学基金项目(51278189);国家自然科学基金重大研究计划项目(91215302) 国家优秀青年基金项目(51422806)
【分类号】：U441.3

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