Multilaser spot tracking technology for bridge structure displacement measuring

Abstract

Summary 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.

Shape Sensing of a Complex Aeronautical Structure with Inverse Finite Element Method

“…In the case an element is free from any strain input (both measured and pre-extrapolated), like the transverse shear, is conventionally posed equal to one to avoid singularity and a small weighting coefficient (⋅) will be adopted to maintain the connectivity between elements. Finally, after the substitution of Equations (2) and 3into Equation 1, the least-square functional of the i-th inverse element can be written as:…”

“…Among the different monitoring approaches available in the literature, displacement monitoring, also known as shape sensing, is receiving more attention especially for usage monitoring [2], although some extensions to damage isolation are present in the literature [3]. Many sensor technologies can be exploited to measure the displacement field, leveraging both on direct and inverse procedures.…”

“…In this case, shape sensing can be performed with inverse algorithms, computing the displacement field from strain measurements acquired on the structure itself. Several approaches are available in the literature which can be classified into four main categories according to their working principle [9]: (1) Numerical integration of experimental strains [10,11]; (2) adoption of continuum functions to approximate the displacement field [12][13][14]; (3) Artificial Neural Networks (ANN) [15,16]; (4) method based on finite-elements discrete variation principles [17][18][19]. Among the latter, the inverse Finite Element Method (iFEM) offers several advantages, including the independence from material properties and loading conditions, the lack of training procedures, and the limited computational demand, which makes it suitable for real-time applications.…”

Multi-point measurement using DIC based on UAV platform

“…At the same time, with the use of the bridge, they need to be replaced and maintained regularly to ensure the normal operation of the equipment. Common non-contact detection methods mainly include Global Navigation Satellite System (GNSS) 2 and laser displacement measurement 3 . GNSS can realize all-weather and automatic bridge monitoring, but the technology is not yet mature, and there are some shortcomings such as expensive equipment and low measurement accuracy (10-20 mm).…”

LSTM approach for condition assessment of suspension bridges based on time-series deflection and temperature data

“…Over 22 major bridges collapsed globally since 2017, and most of the collapses occurred during normal traffic operations (Morgese et al, 2020). Structural health monitoring programs, especially for large bridges provide effective tools for real time evaluation of condition (Maksymenko et al, 2021; Nazarian et al, 2016; Oskoui et al, 2019). Deflection is one of the important parameters for assessment of serviceability and evaluation of structural characteristics of bridges (Cao et al, 2019; Xin et al, 2022).…”