Development and verification of a computer vision technique to measure the response of civil structures

Finding an effective dynamic based measurement system is important to study events such as the collapse of the Tacoma-Narrows Bridge, the devastation of the Kobe earthquake, or human induced vibration on a stadium. Most proposed dynamic based methods for civil structures use acceleration records because acceleration is a global measurement. Acceleration records do not require the use of a reference point, which is a great advantage over other sensing mechanisms. Recording displacements and velocities could provide additional information for the dynamic and static analysis of civil structures. Measurements of velocity and displacements of in-service full-size civil structures are difficult to perform and are predominantly left to laboratory applications because of the specimen's size. The methodology that is proposed in this research is a new way to measure displacements and rotations at specific locations of a structure, using a combination of computer vision techniques and lasers. This enables the displacement to be acquired from in service, full scaled civil structures, not just being limited to laboratory analysis. The methodology reduces the size of the structure such that the displacements at locations of interest can be measured with relatively high accuracy. Further advantages of the methodology include (i) many points can be tracked simultaneously, (ii) wires are not needed between points of interest and the structure, and (iii) measuring additional points is relatively inexpensive. A drawback is a clear line of sight is needed for the application of the proposed methodology. The description of the methodology and results from experimental examples are discussed to show the advantages of the proposed methodology.