\r熊春宝，张雪芳，牛彦波，朱劲松\r
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AuthorsHTML:\r熊春宝，张雪芳，牛彦波，朱劲松\r
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AuthorsListE:\rXiong Chunbao，Zhang Xuefang，Niu Yanbo，Zhu Jinsong\r
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AuthorsHTMLE:\rXiong Chunbao，Zhang Xuefang，Niu Yanbo，Zhu Jinsong\r
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Unit:\r天津大学建筑工程学院，天津 300072\r
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Unit_EngLish:\rSchool of Civil Engineering，Tianjin University，Tianjin 300072，China\r
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Abstract_Chinese:\r为了研究一座大跨径自锚式悬索桥的动态特性，本文采用实时动态差分-全球卫星导航定位系统(RTKGNSS)和加速度计对环境激励下天津富民桥进行监测试验．考虑到RTK-GNSS 系统定位精度的缺陷，提出了一种基于集合经验模态分解(EEMD)法与小波分解(WD)技术的联合降噪方法(EEMDWD)，利用该方法对监测信号进行降噪处理以提高仪器的测量精度．随后，采用快速傅里叶变换(FFT)与随机减量技术(RDT)对降噪信号做进一步分析，从中获取结构的固有频率与相应的阻尼比．同时，为了与实测结果进行对比，建立了结构的有限元模型．分析结果表明：①采用EEMDWD 联合降噪方法可以有效抑制背景噪声的影响，并且明显优于采用单独的EEMD 或者WD 分析的结果；②通过 FFT 分析，成功拾取到了结构的 1 阶固有频率，即 f = 0.587 3Hz ，且 RTK-GNSS 与加速度计两类传感器的模态频率识别结果相一致，进一步验证了RTK-GNSS 系统用于监测环境激励下大跨径桥梁动态响应的可行性；③通过 RDT 分析，成功拾取到了结构的阻尼比，即ξ = 2.12%；④阻尼比实测值与有限元模型分析结果基本吻合，两者相差2.86%．\r
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Abstract_English:\rTo investigate the dynamic characteristics of a self-anchored suspension bridge(i.e. the Tianjin Fumin Bridge)，a real-time kinematic-global navigation satellite system(RTK-GNSS) and an accelerometer are employed to monitor the dynamic responses of the structure under ambient excitation. Considering the defect in positioning accuracy of RTK-GNSS，a combined method(EEMDWD) based on ensemble empirical mode decomposition (EEMD) and wavelet decomposition(WD) is put forward to improve the measurement accuracy of instruments. Subsequently，the natural frequency and the corresponding damping ratio of the structure are extracted based on the fast Fourier transform(FFT) and random decrement technique(RDT). Meanwhile，the finite element model(FEM) of the structure is established for comparison with the field measurement results. Finally，the results show the following. ①The EEMDWD effectively restrains the background noise of RTK-GNSS sensors，and it outperforms the single EEMD and WD methods. ②The first natural frequency of the structure is successfully derived via FFT analysis，i.e f = 0.587 3Hz . Consistent results are obtained from the modal frequency identification using the RTK-GNSS and accelerometer，further verifying that the RTK-GNSS technique is feasible for monitoring the dynamic responses of long-span bridges under ambient excitation. ③The damping ratio is obtained via RDT analysis，i.e ξ = 2.12% . ④The first natural frequency obtained experimentally via FFT analysis coincides with the predicted value based on FEM，with the difference of approximately 2.86% from each other.\r
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Keyword_Chinese:大跨径桥梁；RTK-GNSS；集合经验模态分解；小波降噪；快速傅里叶变换；随机减量技术\r

Keywords_English:long-span bridge；RTK-GNSS；ensemble empirical mode decomposition(EEMD)；wavelet decomposition；fast Fourier transform；random decrement technique\r


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