Rapid three-dimension optical deformation measurement for transmission tower with different loads

A transmission tower is a form of highly indeterminate space structures used extensively. A non-contact optical deformation measurement method is proposed for monitoring the deformation of transmission tower during loading test, which could not be achieved by traditional displacement sensors and resistance strain gauges. This method is based on the close range photogrammetry technology. Paste the artificial markers on the deformation area before loading, and calculate the 3D coordinates of these markers through analyzing the group photos captured in each step. By tracking and comparing the 3D coordinates of the markers among different steps, the load–deformation diagram in 3D form for the whole transmission tower is obtained. It is helpful for further mechanical behavior analysis. Acceptance experiment results indicate the accuracy of this method could reach about 0.1 mm/m. Real-sized model experiment shows that the proposed method can fulfill the efficiency and accuracy requirement of deformation measurement in transmission tower loading test.