Preprint Article Version 2 This version is not peer-reviewed

Monitoring of Structures by a Laser Pointer. Dynamic Measurement of Rotations and Displacements of the Elastic Line of a Bridge: Methodology and First Test

Version 1 : Received: 17 October 2017 / Approved: 17 October 2017 / Online: 17 October 2017 (13:14:18 CEST)
Version 2 : Received: 9 December 2017 / Approved: 11 December 2017 / Online: 11 December 2017 (15:16:12 CET)

How to cite: Artese, S.; Achilli, V.; Zinno, R. Monitoring of Structures by a Laser Pointer. Dynamic Measurement of Rotations and Displacements of the Elastic Line of a Bridge: Methodology and First Test. Preprints 2017, 2017100119 (doi: 10.20944/preprints201710.0119.v2). Artese, S.; Achilli, V.; Zinno, R. Monitoring of Structures by a Laser Pointer. Dynamic Measurement of Rotations and Displacements of the Elastic Line of a Bridge: Methodology and First Test. Preprints 2017, 2017100119 (doi: 10.20944/preprints201710.0119.v2).

Abstract

Deck inclination and vertical displacements are among the most important technical parameters to evaluate the health status of a bridge and to verify its bearing capacity. Several methods, both conventional and innovative, are used for structural rotations and displacement monitoring; no one of these does allow, at the same time, precision, automation, static and dynamic monitoring without using high cost instrumentation. The proposed system uses a common laser pointer and image processing. The elastic line inclination is measured by analyzing the single frames of a HD video of the laser beam imprint projected on a flat target. For the image processing, a code was developed in Matlab® that provides instantaneous rotation and displacement of a bridge, charged by a mobile load. An important feature is the synchronization of the load positioning, obtained by a GNSS receiver or by a video. After the calibration procedures, a test was carried out during the movements of a heavy truck maneuvering on a bridge. Data acquisition synchronization allowed to relate the position of the truck on the deck to inclination and displacements. The inclination of elastic line was obtained with a precision of 0.01 mrad. The results demonstrate the suitability of the method for dynamic load tests, control and monitoring of bridges.

Subject Areas

laser pointer; displacement monitoring; laser fingerprint; video; data synchronization

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