Multilaser spot tracking technology for bridge structure displacement measuring

Abstract

During the structural health monitoring of bridge structures, simultaneous noncontact determination of relative displacements in different points is preferred. The existing measurement displacement methods and systems used for bridge structures deprived of this ability or have the low accuracy and thus automation level that makes their usage for long-term monitoring of bridge structure elements becomes impossible. To avoid the imperfections of existing methods and determining displacements simultaneously in different construction points, we proposed to use the laser spot tracking technology, in which the laser modules are mounted in certain points, and their rays are directed to the translucent screen of a recording device. After screen images recording and processing, one determines displacements of different spots formed by the laser modules on the translucent screen by specialized software. Potential opportunities for this technique are demonstrated during research of a concrete beam deflection in laboratory conditions. The errors of the proposed measurement algorithm were analyzed using computer simulation and laboratory study. The influence of laser modules and screen different spatial positions on the beam deflection measurement was also estimated. Practical application of the proposed system for underground crossing overlap vibration measurements has been showed. Based on the obtained data, several evaluations of its technical state and the residual bearing capacity of a reinforced concrete are made.