Sensing dynamic displacements in masonry rail bridges using 2D digital image correlation
Sensing dynamic displacements in masonry rail bridges using 2D digital image correlation
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DOI：
10.1002/stc.2187
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发表时间：
2018-08-01
影响因子：
5.4
通讯作者：
Soga, Kenichi
中科院分区：
文献类型：
--
作者：
Acikgoz, Sinan;DeJong, Matthew J.;Soga, Kenichi
动态位移测量为砖石铁路桥梁的评估提供了有用的信息，砖石铁路桥梁构成了英国和欧洲桥梁存量的重要组成部分。商业2D数字图像相关（DIC）技术非常适合这一目的。这些系统提供精确的非接触式位移测量同时在桥梁的许多位置与一个容易配置的相机设置。然而，各种各样的误差来源会影响DIC现场测量的分辨率、可重复性和准确性。通常，这些错误是特定于应用程序的，不会被商业软件自动纠正。为了解决这一限制，本文介绍了相关DIC误差的调查，并讨论了在设备设置和数据处理过程中尽量减少这些误差影响的方法。然后描述了DIC在利兹砌体高架桥多点位移测量中的应用案例，通过适当的设置，将光线变化、图像纹理和摄像机运动引起的潜在误差降至最低。像素度量缩放误差保持在最小与使用校准方法，它利用图像中的消失点。然而，将DIC相对位移测量值与桥梁的互补应变测量值进行比较表明，其他误差可能会对DIC测量精度产生重大影响。因此，利用针孔相机和分割畸变模型，从理论上量化了透镜径向畸变和面外运动对测量误差的影响。然后提出了一种校正潜在的面外运动误差的方法。
Dynamic displacement measurements provide useful information for the assessment of masonry rail bridges, which constitute a significant part of the bridge stock in the United Kingdom and Europe. Commercial 2D digital image correlation (DIC) techniques are well suited for this purpose. These systems provide precise noncontact displacement measurements simultaneously at many locations of the bridge with an easily configured camera set-up. However, various sources of errors can affect the resolution, repeatability, and accuracy of DIC field measurements. Typically, these errors are application specific and are not automatically corrected by commercial software. To address this limitation, this paper presents a survey of relevant DIC errors and discusses methods to minimise the influence of these errors during equipment set-up and data processing. A case study application of DIC for multipoint displacement measurement of a masonry viaduct in Leeds is then described, where potential errors due to lighting changes, image texture, and camera movements are minimised with an appropriate set-up. Pixel-metric scaling errors are kept to a minimum with the use of a calibration method, which utilises vanishing points in the image. However, comparisons of DIC relative displacement measurements to complementary strain measurements from the bridge demonstrate that other errors may have significant influence on the DIC measurement accuracy. Therefore, the influence of measurement errors due to lens radial distortion and out-of-plane movements is quantified theoretically with pinhole camera and division distortion models. A method to correct for errors due to potential out-of-plane movements is then proposed.