Stereovision monitoring for entire collapse of a three-story frame model under earthquake excitation

Abstract

Summary During the stage of structural collapse, conventional contact sensors are usually taken away from structure to protect sensors, and the entire displacement curves of structural collapse cannot be acquired. To deal with this problem, a stereovision‐based displacement measurement method is used to monitor the entire structural collapse. To improve measurement accuracy, a three‐step calibration algorithm based on solid circle target is proposed to calibrate stereovision system in this paper. The Digital Image Correlation method is employed to perform sequential image matching of circular target on structural surface. A set threshold of correlation criterion is introduced to eliminate image mismatch, and the reference image is correspondingly updated to conduct later matching under large deformations of structures. A shaking table test of a 3‐story frame model under El Centro earthquake is performed in lab. Experimental results indicate that the displacement curves acquired by the proposed stereovision method and linear variable differential transformers agree well, and this testifies the reliability and effectiveness of the presented stereovision method. Compared with our previous stereovision method, the proposed stereovision method has a higher precision and faster running speed. This demonstrates that the proposed stereovision method is more suitable for the actual use and can monitor the entire process of structural collapse.

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

“…In CV-SHM-GL applications, especially when there is a need for 3D displacement monitoring, two cameras need to be implemented and the pose estimations of the two cameras have to be performed respectively in order to build the connection between two cameras. Shan et al 14 implemented the projective transform to calibrate two cameras and estimate the camera pose to monitor the 3D displacements of a three-story structure under seismic loading and a concrete beam in a destructive test. Chang and Ji 15 implemented projective geometry to monitor the 3D vibration of a bridge deck in wind tunnel test and a frame structure in a shaking table test.…”

Wireless Binocular Stereovision Measurement System Based on Improved Coarse-to-Fine Matching Algorithm

“…However, all the above visual methods require specifc targets on the structure as the features or tracking points. Te targets are artifcial markers with designed patterns [24] (circle and square) or natural keypoints [25] selected from the structure surface. However, the methods that adopt the artifcial targets are more accurate than the methods based on natural features [26].…”

Infrared Thermography Measurement for Vibration-Based Structural Health Monitoring in Low-Visibility Harsh Environments

“…Compared with measurement using traditional sensors, image-based measurement is a noncontact measurement technology that does not interfere with the test object. Image-based measurement can be divided according to the usage of marked [ 9 , 18 , 19 , 20 ] or unmarked points [ 21 , 22 , 23 ]. Measurement with marked points involves attaching a specific pattern to a structure for obtaining a strong contrast between the structure and background for acquiring a clear image.…”