环境激励下钢筋混凝土拱桥模态参数识别

为正确选择模态参数识别方法,对某钢筋混凝土拱桥进行了环境振动试验,采用频域、时域和时频分析方法——峰值拾取法(PP)、随机子空间识别(SSI)以及基于经验模态分解(EMD)和随机减量技术(RDT)的方法——识别其模态参数;比较了3种模态参数识别方法的特点和识别结果,并与有限元法计算结果进行了比较.研究结果表明:峰值拾取法的识别速度快,识别的频率较可靠,但识别过程需要较多人工干预;随机子空间识别的理论体系完备,适合程序实现,识别过程能较好地抵消测试过程中噪声等的影响;由于模态混叠的影响,EMD-RDT识别结果具有一定随机性.

Modal Parameter Identification of Reinforced Concrete Arch Bridge under Ambient Excitation

An ambient vibration test was conducted on a reinforced concrete arch bridge to correctly choose a modal parameter identification method.Modal parameters were identified using frequency domain,time domain and time-frequency analysis methods.They are the peak-picking,the stochastic subspace identification and the EMD-RDT method based on empirical mode decomposition(EMD) and random decrement technique(RDT),respectively.The comparisons between the results get from the above different methods and the finite element method(FEM) were carried out.The research result shows that the peak-picking has a very high identification speed and can identify natural frequencies reliably,but it needs a lot manual intervention.The stochastic subspace identification has a complete theoretic system and suits for programming realization,and its identification process can neutralize the influence of noises in dynamic tests.Because of mode mixing,the identification results of the EMD-RDT method have some random properties.