Image‐based back analysis for tension estimation of suspension bridge hanger cables

Abstract

Summary In suspension bridges, hanger cables are the main load‐supporting members. The tension of the hanger cables of a suspension bridge is a very important parameter for assessing the integrity and safety of the bridge. In general, indirect methods are used to measure the tension of the hanger cables of a suspension bridge in use. A representative indirect method is the vibration method, which extracts modal frequencies from the cables' responses and then measures the cable tension using the cables' geometric conditions and the modal frequencies. In this study, ambient vibration tests were conducted on a suspension bridge in use to verify the validity of the image‐based back analysis method, which can estimate the tension of remote hanger cables using the modal frequencies as a parameter. The tension estimated through back analysis, which was conducted to minimize the difference between the modal frequencies calculated using finite element analysis of the hanger cables and the measured modal frequencies, was compared with that measured using the vibration method. It was confirmed that reliable tension estimation is possible even with low‐order modal frequencies when the image‐based back analysis method is used.

Static and dynamic response analysis of stay cables using terrestrial laser scanning and vibration measurements

“…The dynamic identification method based on determining the unknown cable tension from the geometric stiffness that can be evaluated for measured frequencies (known the cable mass) is the most used, because it is a nondestructive method which guarantees high efficiency [3], [4], [5]. Similarly to other model based methods, this approach requires refined mechanical formulations describing the dependence of the spectral properties on the structural parameters [6], [7].…”

Modal analysis and tension estimation of stay cables using noncontact vision‐based motion magnification method

“…Furthermore, vibration measurement by video camera is less expensive, easier to operate, and deployable for frequent measurement compared with the abovementioned noncontact measurement systems. Full‐field structural dynamic response of structures can be obtained accurately from video camera measurements with advanced image‐processing algorithms 16–19 . Moreover, difficulty in capturing microvibration of civil structures in ambient condition can now be overcome by recent advancements of computer vision such as using the phase‐based video motion magnification (PVMM) technique 20 .…”

“…Full-field structural dynamic response of structures can be obtained accurately from video camera measurements with advanced image-processing algorithms. [16][17][18][19] Moreover, difficulty in capturing microvibration of civil structures in ambient condition can now be overcome by recent advancements of computer vision such as using the phase-based video motion magnification (PVMM) technique. 20 By this method, microvibration of an object is amplified within the frequency of interest, and the spatial displacement response can be extracted using available advanced image-processing techniques such as centroid detection, 21,22 edge detection, 23 subpixel orientation code matching, 24 principal component analysis, and blind source separation.…”

Estimation of Live Load Distribution Factor for a PSC I Girder Bridge in an Ambient Vibration Test

“…The procedure for updating the finite element model mostly involves finding the most suitable structural parameter that can minimize the error between the measurement and analysis results by solving the optimization problem. Various types of responses, such as displacement, natural frequency, and mode shape, can be considered as references in matching the actual structure and the finite element model [21][22][23][24][25]. Dynamic characteristics for the natural frequency and mode shape can be measured using the ambient vibration test.…”