Measuring accurate deformation distribution of large‐scale structures inexpensively and efficiently is a crucial challenge of structural health monitoring. Phase‐based imaging technique has great potential for accurate and robust multipoint displacement measurement in the field. In this study, the sampling Moiré method—one of the promising optical techniques—was applied to the displacement measurement of a concrete bridge for the high‐speed railway in Japan. Using retroreflective Moiré markers, the two‐dimensional in‐plane displacements at multiple locations could be easily measured from recorded digital images at a distance of 20 m regardless of day and night. Results of the dynamic deflection obtained from the sampling Moiré method were in good agreement with those from a conventional laser Doppler vibrometer. The time series of two‐dimensional displacement analyses when the outbound or inbound trains passed at the speed of 150 or 320 km/h through the bridge revealed that the points at the centre and the quarter of the bridge span demonstrated complex deformation behaviour showing elliptical rotation. The effects of random noise of the recorded image were quantitatively investigated, and the air fluctuation was discussed from the field experiments. We proved that measurements using the sampling Moiré method could be more stable at night than daytime.

中文翻译：

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基于重复模式相位分析的采样莫尔法测量混凝土桥梁位移。

廉价，有效地测量大型结构的精确变形分布是结构健康监测的关键挑战。基于相位的成像技术在现场进行准确，可靠的多点位移测量具有巨大的潜力。在这项研究中，采样莫尔方法（一种有前途的光学技术）被应用于日本高速铁路混凝土桥梁的位移测量。使用逆向反射莫尔标记，无论白天和黑夜，都可以从20 m距离处记录的数字图像轻松测量多个位置的二维面内位移。从采样莫尔方法获得的动态偏转结果与常规激光多普勒测振仪的结果吻合良好。当出站或进站的火车以150或320 km / h的速度通过桥梁时的二维位移分析时间序列显示，桥梁跨度的中心和四分之一处的点表现出复杂的变形行为，显示出椭圆旋转。定量研究了记录图像的随机噪声的影响，并通过野外实验讨论了空气波动。我们证明，使用采样莫尔条纹法进行的测量在夜间比白天更稳定。定量研究了记录图像的随机噪声的影响，并通过野外实验讨论了空气波动。我们证明，使用采样莫尔条纹法进行的测量在夜间比白天更稳定。定量研究了记录图像的随机噪声的影响，并通过野外实验讨论了空气波动。我们证明，使用采样莫尔条纹法进行的测量在夜间比白天更稳定。