Time：May15 14:25 -14:50
Title: On the technique for extracting bridge dynamic property from a moving test vehicle/基于测量车提取桥梁动力特征参数的技术研究
Abstract：The technique for extracting the bridge frequencies from a test vehicle moving over the bridge was first proposed by Yang and co-workers in 2004 in Taiwan, which has been referred as the indirect approach of measurement for bridge frequencies. At the time, the test vehicle was modeled as a single-degree-of-freedom sprung mass unit and the bridge was modeled as a simply supported beam. Mathematically, it was demonstrated that the bridge frequencies can be clearly identified from the Fourier spectrum of the vertical response of the moving vehicle. In the following year, this technique was proved to be feasible in a field test conducted in a highway bridge located in the northwestern coast of Taiwan. In application of the technique, road surface roughness has been a source of pollution, which can reduce the identifiability of the bridge frequencies. To this end, various techniques have been proposed by the author and coworkers to alleviate the effect of road surface roughness, including the empirical mode decomposition, subtraction of two connected vehicles’ spectra for reducing road roughness, and singular spectrum analysis with band-pass filter for suppressing the vehicle frequency. Moreover, the Hilbert transformation has been adopted process the vehicle response for the purpose of constructing the mode shapes of the bridge. In this presentation, focus will be placed on the issues of improvement for both the hardware and software parts of the indirect technique.
标题：以移动试验车量测桥梁动态特性之技术
内容：以移动车辆量测所通过桥梁之频率，係由杨和研究群于2004年在台湾所首创，此法又称为桥梁频率之间接量测法。 在当时，试验车係模拟为一单自由度的弹簧质量单元，而桥梁则模拟为一简支梁。从数学推导中，可证明从车辆垂直响应的傅立叶频谱中，确可识别出桥梁的频率。 翌年，在台湾西北海岸的一座桥梁的现地实验中， 进一步证实此法是可行的。采用此法时，路面的粗糙度是一个主要的污染源，它会降低桥频的识别度。为此，作者和研究群曾提出各种技术来降低路面粗糙度的影响，所采用的手段包括：经验模态分解法、两个联结车辆响应频谱消减法、以及以含带通滤波的奇异频谱分析消除车频的方法等。此外， 也曾以希尔伯特转换处理车辆响应，建立桥梁的模态。在本报告中，重点係摆在间接量测法的硬件和软件的改良要点。
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