Displacement measurement of an existing long span steel box-girder using terrestrial laser scanning

To make use of a new technology in the field of structural health monitoring, various displacement measuring techniques such as a global positioning system (GPS) and vision-based techniques have been studied and proposed. It was previously introduced a new displacement measuring technique using terrestrial laser scanning (TLS) that remotely samples the surface of an object using laser pulses and generates the three-dimensional (3D) coordinates of numerous points on the surface. In this paper, for an assessment of the capabilities of the measuring technique about existing structures, the field tests for vertical displacement measurement of an existing long span steel box-girder are experimentally carried out. The performance of the technique is evaluated by comparing the displacements obtained from TLS system and displacements directly measured from linear variable displacement transducer (LVDT).