Application of digital photogrammetry techniques in identifying the mode shape ratios of stay cables with multiple camcorders

A simple digital photogrammetry technique using artificial targets is developed to conduct the synchronized ambient vibration measurements at different locations of a stay cable with multiple camcorders for the identification of mode shape ratios. To compensate the restrictions imposed by the adoption of budget equipment, elaborate adjustments in scale, synchronization, and baselines are performed. Based on the on-site measurements for three stay cables, it is verified that the proposed methodology can effectively measure the ambient vibration responses of stay cables and attain the same order of accuracy in the identification of mode shape ratios as that of high-resolution velocimeters. (C) 2015 Elsevier Ltd. All rights reserved.