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State of the Art of Geodetic Bridge Monitoring
Abstract
To ensure the structural health of bridges and their compliance with normative regulations, e.g. Eurocodes, it is important to know their displacements and their vibration characteristics including natural frequencies and amplitudes. Until recently, geodetic sensors were not capable to measure bridge vibrations due to the low measurement rate of the sensors. This changed within the last years. We therefore compare different state-of-the-art techniques for geodetic bridge monitoring, including total stations, radar systems, image-based approaches and GNSS sensors.
... При проведении опытной эксплуатации системы мониторинга в программном обеспечении целесообразно предусмотреть модуль визуализации измеренных данных [3][4][5][6][7] . Визуализацию данных, полученных с инклинометров, целесообразно выполнять путём построения диаграмм прогибов пролётного строения моста при движении подвижного состава . ...
... где ε i -деформация в i-м плече моста; S R -общая чувствительность системы; ε B -эффективная деформация, измеренная прибором . 5 . 5 Отчёт об опытно-конструкторской работе по теме «Создание системы мониторинга потенциально опасных объектов железнодорожного транспорта с использованием систем ГЛОНАСС/GPS/GALILEO» . ...
... 5 . 5 Отчёт об опытно-конструкторской работе по теме «Создание системы мониторинга потенциально опасных объектов железнодорожного транспорта с использованием систем ГЛОНАСС/GPS/GALILEO» . -М .: ФГУП «Защи-таИнфоТранс», 2020 . ...
Reliability of transport artificial structures and transit of trains at sanctioned speed should be provided with the necessary and sufficient load-bearing capacity, strength, rigidity, and stability of engineering structures.
The objective of this work was to substantiate the possibility of using well-known methods for controlling the stress-strain state of structures using automated systems of structural health monitoring of bridge spans.
It is extremely important regarding operation of transport artificial structures designed according to the standards of the first half of the 20th century.
Under these conditions, the experimental determination of the stress-strain state of bearing structures of bridges becomes the most important component of the task of a comprehensive assessment of physical wear and tear as well as of operational reliability of the structures. Monitoring the structural health and technical condition of bridges and planning of timely measures aimed at the repair, strengthening or reconstruction of spans will extend their service life and ensure safety during operation.
Maximum permissible deflections of spans under a movable temporary vertical load have been revealed since to ensure smooth movement of vehicles it is necessary to control horizontal longitudinal and transverse displacements of the top of the bridge piers, as well as vertical settlements.
The paper suggests methods of interpreting data measured by inclinometers and electric strain gauges, tensiometers to use them in an automated system for monitoring the structural health of railway bridges. The method of strain measurement is described in detail in the proposed options for installing resistance strain gauges on structures to measure tensile-compression stresses and longitudinal forces due to a temporary vertical load.
Monitoring the technical condition of bridge structures, using the methods for measuring deflections and deformations proposed by the authors in this article, will make it possible to assess the change in bearing capacity of the structure over the entire period of operation. The study used regulations and experience of the Russian Federation and the Republic of Kazakhstan.
... A monitoring system, as a means of control and accountability, represents a technology of informational support for the decision-making process regarding the monitoring of parameters of engineering structures and individual construction elements at all stages of their life cycle, carried out through systematic or periodic observation of their technical condition [1][2][3][4][5]. ...
... Railway transportation facilities are unique systems that function in extremely diverse natural and climatic conditions [1][2][3]. Ensuring the safe operation of this system is a complex and multifaceted task [5][6][7][8][9][10]. Maintaining the railroad track and artificial structures in a safe technical condition is the main task of the operational service [11][12]. ...
The paper presents the results of computational analysis of the stress-strain state of reinforced concrete spans of the railway (single-track railway line) overpass over the highway, under specified loads using spatial finite element models. The static load consists of a cohesion of three TEM-18 diesel locomotives and two loaded gondola cars (up to 25 tons per axle). The purpose of this study was to ensure reliable and safe operation of artificial structures on the railroads, as there is a constant increase in transit freight trains from China through the territory of Kazakhstan to near and far abroad, and often the load on the axle reaches 25 tons, and sometimes larger values – up to 27 tons per axle. The results of the study are recommended to be used for inspections and tests of typical girder bridge spans, as well as in the case of monitoring their technical condition with increasing operational loads.
... Until recently, only vertical and horizontal displacements could be determined by geodetic measurements. Today, with the development of geodetic equipment, increasing resolution, additional sensors for faster reading, and automatic prism monitoring, it is possible, when geodetic measurements are taken together with very accurate static measurements, to perform dynamic response measurements in various monitoring [1,2]. It should be noted that geodetic methods can be used in a very simple way to obtain quality data on the vibration velocity measurements with a seismograph and an associated geophone. ...
Building structures are subject to various deformations caused by external and internal factors. Deformations are determined by various methods in the form of monitoring. It is very important to monitor the dynamic vibration response on bridge structures since these measurements allow us to identify any possible damage over time and take appropriate action. Our experiment, described in this article, is based on the use of non-contact methods, among which we used a geodetic instrument RTS (Robotic Total Station) and a seismograph to measure vibrations. The purpose and novelty of our work are reflected in the use of geodetic instruments to determine the dynamic response and synchronization of the obtained results. When using RTS technology, we increased data acquisition from 9 to 26 measurements per second. Comparative analysis of the measured signals was performed using FFT (Fast Fourier Transformation) and LSP (Lomb–Scargle Periodogram), based on LSSA (Least-Squares Spectral Analysis). The results showed us that when using the RTS geodetic instrument, it is possible to achieve frequency spectra comparable to those measured with a seismograph instrument. By increasing the number of measurements, the RTS method can be used to obtain more continuous data, which are essential for dynamic analyses.
... Within the last decade the resolution and measurement rates of geodetic sensors has been improved significantly and new sensors like ground based interferometric radar have been developed. As shown by Lienhart and Ehrhart [7], modern geodetic sensors can be used for static and dynamic bridge monitoring. This article demonstrates in detail how the measurement rate of a standard total station can be increased to be capable of dynamic monitoring. ...
Robotic total stations (RTS) are frequently used for the measurement of temperature induced bridge deformations or during load testing of bridges. In experimental setups, total stations have also been used for the measurement of dynamic bridge deformations. However, with standard configurations the measurement rate is not constant and on average an update rate of 7–10Hz can be achieved. This is not sufficient for the vibration monitoring of bridges considering their natural frequencies which are also in the same range. In this paper, we present different approaches to overcome these problems. In the first two approaches we demonstrate how the measurement rate to prisms can be increased to 20Hz to determine vertical deformations of bridges. Critical aspects like the measurement resolution of the automated target tracking and the correct sequence of steering commands are discussed. In another approach we demonstrate how vertical bridge vibrations can be measured using an image assisted total station (IATS) and corresponding processing techniques. The advantage of image-based methods is that structural features of a bridge like bolts can be used as targets. Therefore, no expensive prisms have to be mounted and access to the bridge is not required. All approaches are verified by laboratory investigations and their suitability is proven in a field experiment on a 74m long footbridge. In this field experiment the natural frequencies derived from the total station measurements are compared to the results of accelerometer measurements.
Purpose: assessing the performance of the monitoring system for engineering structures and assessing the current state of the structures of the cable-stayed bridge across the Petrovsky Canal in the alignment of the Western High-Speed Diameter highway in the city of St. Petersburg due to the occurrence of emergency situations in which accelerometers on the pylons record values exceeding the limit. Methods: statistical data from the databases of the existing system of monitoring engineering structures is used to obtain the results. The tasks, set within the framework of the study, are accomplished by applying the theoretical methods of scientific knowledge: the analytical method, the mathematical statistics theory, induction. Results: the resulting structural approach to assessing the performance of the monitoring system for engineering structures on cable-stayed bridges makes it possible to reduce the number of false alarms of the system and assess the current state of the bridge structure. Within the framework of the III stage of the structural approach, it is proposed to develop a methodology for assessing the performance of the monitoring system for engineering structures with subsequent assessment of the current state of cablestayed bridge structures. Practical significance: the results of the work are important for construction as they expand the understanding of the features of the mechanism of soil freezing.
Purpose: assessing the performance of the monitoring system for engineering structures and assessing the current state of the structures of the cable-stayed bridge across the Petrovsky Canal in the alignment of the Western High-Speed Diameter highway in the city of St. Petersburg due to the occurrence of emergency situations in which accelerometers on the pylons record values exceeding the limit. Methods: statistical data from the databases of the existing system of monitoring engineering structures is used to obtain the results. The tasks, set within the framework of the study, are accomplished by applying the theoretical methods of scientific knowledge: the analytical method, the mathematical statistics theory, induction. Results: the resulting structural approach to assessing the performance of the monitoring system for engineering structures on cable-stayed bridges makes it possible to reduce the number of false alarms of the system and assess the current state of the bridge structure. Within the framework of the III stage of the structural approach, it is proposed to develop a methodology for assessing the performance of the monitoring system for engineering structures with subsequent assessment of the current state of cable-stayed bridge structures. Practical significance: the results of the work are important for construction as they expand the understanding of the features of the mechanism of soil freezing.
Dynamic loads from rolling stock are distributed along the entire length of the bridge spans. Therefore, using a limited number of load cells only in the central (most loaded) zone of the span is not enough. The purpose of this work was to determine the stress–strain state of the load-bearing elements of steel girder superstructures and polygonal trusses of railway bridges during the operation of freight rolling stock with increased axial loads. The authors substantiate the expediency of using software and hardware complexes when measuring stresses in the superstructures of bridges designed and built according to the standards of different periods, allowing to take into account the technical characteristics (weight and speed of the train) of the rolling stock passing over the bridge. The construction of correlational dependencies of these characteristics on the controlled parameters of the stress–strain state is the basis of the decision-making system on the load capacity of the structure. The paper also presents the results of measurements of fiber stresses arising in the transverse and longitudinal beams of the roadway and truss belts from the effects of various types of rolling stock. The analysis of the measured fiber stresses during the operation of superstructures made it possible to identify the most defective superstructure structures for the classification of structures by load-bearing capacity.
Assessment of load-carrying capacity of metal and reinforced concrete railway bridges of different length built in 1930 - 2007, operated under modern heavy-weight trains, is considered in the article. To understand and cause the occurrence of deformations in structural elements, it is necessary to analyze the operation of bridge spans under conditions of increasing axial loads and traffic speeds. Deformation processes cause the appearance of defects, structural failures and accidents, which leads to material and environmental damage. The funds spent on bridge serviceability reconstruction are much more than those invested in protective measures. The main task is to study the interaction of bridges and rolling stock (bridge-train system), namely, the greatest influence from dynamic deformations and movements. The purpose of this work is to study the possibility of making way for heavy-weight rolling stock over the bridge spans. The research is based on the study of their load-carrying capacity estimation by test and classification methods. The paper presents the results of the measurements of the stress-strain state of bridge structures, obtained by the authors, using strain-measuring hardware-software complex (SMHSC). Depending on the results obtained, the decisions on the possibility of making way for heavy rolling stock with the axle load of 245-275 kN on the metal and reinforced concrete bridge spans are made.
Determining the displacements and consequent deformations of structures is a demanding branch of engineering. Displacements are most often determined by geodetic methods, among which high-precision non-contact methods have recently taken the lead. Engineering geodesy is an indispensable part of construction projects. In the desire for efficient and fast measurements, the technology of terrestrial laser scanning (TLS) and the use of robotic total station (RTS) and other geodetic methods are becoming more and more useful for engineers. In the presented study, we focused on the measurement and comparison of vertical displacements with various mentioned equipment and the determination of the influence of meteorological conditions on the displacements of timber beams that we used to perform the experiment. Measurements were performed both in the laboratory and outdoors. A novelty in the work was the use of a TLS scanner to determine the evaluation of small value displacements and the analysis of the usability of geodetic measuring equipment. In the Materials and Methods section, we describe the equipment used and the characteristics of the beams. The Results section describes the experimental outcomes, which include the performance of experimental analysis of vertical displacements of timber beams under different meteorological conditions. Altogether, the results consist of geodetic measurements and the processing of measured data. The results of measurements of vertical displacements with a terrestrial laser scanner were compared with the results obtained with a robotic total station were evaluated and compared with the displacements calculated from static analysis and the results of other methods used.
This volume gathers the latest advances and innovations in the field of structural health monitoring, as presented at the 8th Civil Structural Health Monitoring Workshop (CSHM-8), held on March 31–April 2, 2021. It discusses emerging challenges in civil SHM and more broadly in the fields of smart materials and intelligent systems for civil engineering applications. The contributions cover a diverse range of topics, including applications of SHM to civil structures and infrastructures, innovative sensing solutions for SHM, data-driven damage detection techniques, nonlinear systems and analysis techniques, influence of environmental and operational conditions, aging structures and infrastructures in hazardous environments, and SHM in earthquake prone regions. Selected by means of a rigorous peer-review process, they will spur novel research directions and foster future multidisciplinary collaborations.
Global Navigation Satellite Systems (GNSS) like GPS, Galileo, GLONASS and Beidou are used for monitoring of civil structures and natural phenomena since the 1980s. However, most of the implementations were either short term or realized in a very controlled environment. In this article we report about the experiences of more than 20 years of GNSS based monitoring of a large-scale object. In 1999 the GNSS monitoring system was developed and installed at a deep-seated gravitational mass movement in Austria and it is still operating. The system gradually evolved during the years of operation to maintain a reliable operation and to take new developments of information and communication technology (ICT) into account. This included the change from radio communication to UTMS and continuous maintenance of the hardware (revision of GNSS stations, revision of solar collectors, exchange of batteries) as well as software maintenance (Firmware updates of GNSS receivers, software updates, change to new operating systems). Especially the constant changes in the used software system results in maintenance time, which is often underestimated. From these experiences we derive lessons learned which can be a guideline for other long-term GNSS based monitoring systems.
Today, many large-scale civil engineering structures are permanently monitored to provide early warnings and to initiate counter actions from structural failure. Total station measurements are commonly used to determine 3D movements of selected points with measurement intervals of several minutes or hours. However, these measurements do not provide information on the vibration behavior of the structures. For this purpose, other sensors like accelerometers have to be installed on the object. In this paper, we present a monitoring system based on a state of the art image assisted total station (IATS) suitable for the measurement of absolute 3D coordinates and the determination of the structure's natural frequencies. The 3D coordinates can be determined with an accuracy of a few millimeters using conventional total station measurements. For analyzing the structure's natural frequencies, the telescope camera of the IATS is used in combination with dedicated image processing techniques optimized for artificial and natural targets. While the determination of 3D coordinates based on total station measurements is common practice, the idea of using the total station's image data for frequency analysis is new. Consequently, investigations on the achievable performance are pending for commercially available products. We therefore evaluate the potential of this technique at a life-size footbridge by comparison with accelerometer measurements. We demonstrate that with our developed monitoring concept and state of the art hardware, accelerometer measurements can be replaced in several monitoring situations by IATS measurements and image processing techniques.
This article summarises discussions concerning the definition of "engineering geodesy" within the German Geodetic Commission. It is noted that engineering geodesy by means of its tasks, methods and characteristics is an application-oriented science whose research questions often arise from observed phenomena or from unsolved practical problems. In particular it is characterised by the professional handling of geometry-related problems in a cost-effective manner that includes comprehensive quality assessment at all phases of the problem solution - from planning through measurement to data processing and interpretation. The current methodical developments are primarily characterised by the increasing integration of the measurement and analysis into challenging construction, production and monitoring processes as well as by the transition to spatially continuous methods. A modern definition of engineering geodesy is proposed at the end of this article.
Lateral deflections of a timber pedestrian bridge in Patras, Greece, excited by pedestrians were measured using a robotic total station (RTS) in six annual surveys. Analysis of the data indicated a drop of 1.6 Hz in the natural frequencies of the bridge between 2007 and 2008 and then a gradual drop of approximately 8% between 2008 and 2012. This frequency drop was consistent with signs of decay, accelerometer data, and a drop in the natural frequencies along the vertical axis, and was most probably prompted by a strong earthquake and especially by an extraordinary (for the area) icing event. The overall changes in the response of the bridge to dynamic loads were consistent with the feelings of discomfort for pedestrians crossing this bridge. This is probably the first case of repeated measurements of deflections documenting deterioration of the structural health of a bridge at this intensity and scale of time.
One fundamental component of early warning systems for natural hazards
is displacement monitoring. Spaceborne SAR Interferometry has proven to
be a powerful remote sensing tool for this task. Lately new ground-based
SAR instruments are available. Their application field is wide and they
combine high resolution and accuracy with the classical benefits of
remote sensing techniques.
Here, the principles of the microwave interferometer IBIS are presented,
as well as its advantages and disadvantages compared to common
monitoring techniques. IBIS can be operated in two modes: IBIS-S is a
microwave interferometer capable of high frequency displacement
monitoring of buildings and structures (up to 200 Hz); IBIS-L is a
ground-based SAR for long-term displacement monitoring of buildings and
natural phenomena as landslides, glaciers, etc.
Exemplary three applications are presented: the use of IBIS-S for
dynamic monitoring of a chimney; the use of IBIS-L for displacement
monitoring in an active quarry and the long-term operation of IBIS-L as
part of a “Volcano Fast Response System” (VFRS) on an active
volcano.