A Novel Dense Full-Field Displacement Monitoring Method Based on Image Sequences and Optical Flow Algorithm

Abstract

This paper aims to achieve a large bridge structural health monitoring (SHM) efficiently, economically, credibly, and holographically through noncontact remote sensing (NRS). For these purposes, the author proposes a NRS method for collecting the holographic geometric deformation of test bridge, using static image sequences. Specifically, a uniaxial automatic cruise acquisition device was designed to collect static images on bridge elevation under different damage conditions. Considering the strong spatiotemporal correlations of the sequence data, the relationships between six fixed fields of view were identified through the SIFT algorithm. On this basis, the deformation of the bridge structure was obtained by tracking a virtual target using the optical flow algorithm. Finally, the global holographic deformation of the test bridge was derived. The research results show that: The output data of our NRS method are basically consistent with the finite-element prediction (maximum error: 11.11%) and dial gauge measurement (maximum error: 12.12%); the NRS method is highly sensitive to the actual deformation of the bridge structure under different damage conditions, and can capture the deformation in a continuous and accurate manner. The research findings lay a solid basis for structure state interpretation and intelligent damage identification.

A review of computer vision–based structural health monitoring at local and global levels

“…Structural behavior analysis Tian and Pan 128 : deflection profile of railway bridge Guo and Zhu 183 : sound barriers of a viaduct Deng et al 184 : deflection profile of suspension bridge model Ji et al 185 : flexural, shear, and sliding deformation behaviors of RC wall Load distribution estimation Dong 125 : distribution factor of a pre-stressed concreted girder bridge Load carrying capacity analysis Lee et al 187 : load capacity analysis of a steel girder bridge Dong 125 : load rating of a pre-stressed concreted girder bridge Dynamic analysis Xu et al 16 : cable-stayed footbridge Zhao et al 188 : tower of a scaled model of a cable-stayed bridge under earthquake loads Dong et al 149 : grandstand, stadium Ngeljaratan and Moustafa 189 : ABC bridge Modal identification Ji and Chang: stayed cable Chen et al 156,181 : cantilever beam Yang et al 194,195 : aluminum frame structure Fioriti et al 196 : ancient constructions such as buildings and bridges Tian et al 167 : beam Dong et al 149 : grandstand Hoskere et al 163 : suspension bridge (foot bridge) Harmanci et al 200 : steel frame Model updating Dong et al 201 : a pre-stressed concreted girder bridge Feng and Feng 192 : aluminum frame structure Damage detection…”

“…Guo and Zhu 183 investigated the behavior of the sound barriers of a viaduct when a train was crossing by using the Lucas–Kanade template tracking-based displacement measurement method. Deng et al 184 applied an uniaxial automatic cruise camera system to capture the images of different sections of a suspension bridge model in laboratory and based on the overlaps between the consecutive sections, they extracted the static contour of the bridge by using SIFT matching. By tracking the contour change of the bridge under different loads and damage cases, they extracted the bridge profile change behaviors.…”

Novel Approach to Extract Dense Full-Field Dynamic Parameters of Large-Scale Bridges Using Spatial Sequence Video

“…Based on the previous study of our research team (Wang et al, 2016;Shao et al, 2020;Deng et al, 2020), a 1:30 model of the Taohuayu Yellow River Bridge is constructed. A total of 52 C30 concrete deck slabs (1.16×0.45×0.2 m) are prepared and laid on a steel box girder to simulate vehicles on the bridge and serve as counterweights.…”

“…However, many tests only obtain the motion response of the critical structural parts (Feng et al, 2017;Dong et al, 2019). In this study, a high-speed camera system, proposed in previous work (Deng et al, 2020), was adopted as a noncontact remote bridge intelligent sensing holographic monitoring system to obtain the structural dynamic response. The main components include holographic vision sensor, PTZ, and control system, it is set up 5 m from the test bridge facade.…”

“…The fixed angle rotation of the camera is controlled by a computer to realize the acquisition of the fixed-section image of the test bridge at a fixed position, as shown in Figures 7 and 8. In this experiment, according to the previous research results (Deng et al, 2020), the entire bridge is divided into six visual fields to collect image information. The environmental action, vehicle load, and structural state are known and controllable variables in the test.…”