Development of a wireless displacement measurement system using acceleration responses

Displacement measurements are useful information for various engineering applications such as structural health monitoring (SHM), earthquake engineering and system identification. Most existing displacement measurement methods are costly, labor-intensive, and have difficulties particularly when applying to full-scale civil structures because the methods require stationary reference points. Indirect estimation methods converting acceleration to displacement can be a good alternative as acceleration transducers are generally cost-effective, easy to install, and have low noise. However, the application of acceleration-based methods to full-scale civil structures such as long span bridges is challenging due to the need to install cables to connect the sensors to a base station. This article proposes a low-cost wireless displacement measurement system using acceleration. Developed with smart sensors that are low-cost, wireless, and capable of on-board computation, the wireless displacement measurement system has significant potential to impact many applications that need displacement information at multiple locations of a structure. The system implements an FIR-filter type displacement estimation algorithm that can remove low frequency drifts typically caused by numerical integration of discrete acceleration signals. To verify the accuracy and feasibility of the proposed system, laboratory tests are carried out using a shaking table and on a three storey shear building model, experimentally confirming the effectiveness of the proposed system.open3

Bridges Structural Health Monitoring and Deterioration Detection Synthesis of Knowledge and Technology

INE/AUTC 10.0

Smart FRP Composite Sandwich Bridge Decks in Cold Regions

INE/AUTC 12.0

Wireless Sensors for Health Monitoring of Marine Structures and Machinery

Remote structural and machinery health monitoring (SMHM) of marine structures such as ships, oil and gas rigs, freight container terminals, and marine energy platforms can ensure their reliability. However, the wired sensors currently used in these applications are difficult and expensive to install and maintain. Wireless Sensor Networks (WSN) can potentially replace them but there are significant capability gaps that currently prevent their long-term deployment in the harsh marine environment and the structurally-complex, compartmentalised, all-metal scenarios with high volume occupancy of piping, ducting and operational machinery represented by marine structures. These gaps are in sensing, processing and communication hardware and firmware capabilities, reduction of power consumption, hardware assembly and packaging for reliability in the marine environment, reliability of wireless connectivity in the complex metal structures, and software for WSN deployment planning in the marine environment. Taken together, these gaps highlight the need for a systems integration methodology for marine SMHM and this is the focus of the research presented in this thesis. The research takes an applied approach by first designing the hardware and firmware for two wireless sensing modules specifically for marine SMHM, one a novel eddy-current-based 3D module for measuring multi-axis metal structural displacement, the second a fully integrated module for monitoring of structure and machinery reliability. The research then addresses module assembly and packaging methods to ensure reliability in the marine environment, the development of an efficient methodology for characterising the reliability of wireless connectivity in complex metal structures, and development of user interface software for planning WSN deployment and for managing the collection of WSN data. These are then individually and collectively characterised and tested for performance and reliability in laboratory, land-based and marine deployments. In addition to the research outcomes in each of these individual aspects, the overall research outcome represents a systems integration methodology that now allows deployment, with a high expectation of reliability of marine SMHM WSNs

LOCAL POSITIONING SYSTEMS VERSUS STRUCTURAL MONITORING: A REVIEW

SUMMARY Structural monitoring and structural health monitoring could take advantage from different devices to record the static or dynamic response of a structure. A positioning system provides displacement information on the location of moving objects, which is assumed to be the basic support to calibrate any structural mechanics model. The global positioning system could provide satisfactory accuracy in absolute displacement measurements. But the requirements of an open area position for the antennas and a roofed room for its data storage and power supply limit its flexibility and its applications. Several efforts are done to extend its field of application. The alternative is local positioning system. Non-contact sensors can be easily installed on existing infrastructure in different locations without changing their properties: several technological approaches have been exploited: laser-based, radar-based, vision-based, etc. In this paper, a number of existing options, together with their performances, are reviewed. Copyright © 2014 John Wiley & Sons, Ltd

Wireless wake-up sensor network for structural health monitoring of large-scale highway bridges

To realize in-situ structural health monitoring of critical infrastructure such as bridges, we present a powerful, but also low power and flexible, wireless sensor node utilizing a wake-up transceiver. The sensor node is equipped with several kinds of sensors, such as temperature, pressure and acceleration for in-situ monitoring of critical infrastructure. In addition to these commonly used sensors in wireless sensor networks, some nodes are equipped with global navigation satellite system receivers (GNSS) and others with tilt and acceleration sensors of very high accuracy that were developed by Nothrop Grumman LITEF GmbH. We present a low power wakeup multi-hop routing protocol that is able to transmit data with little overhead by supporting the use of wake-up receivers in combination with long-range communication radios. The wireless sensor nodes and the routing protocol are tested at a large-scale highway bridge in south-west Germany, where a prototype network was installed in June 2015 following a first test installation earlier in June at the same bridge. A gateway node equipped with a Global System for Mobile Communications (GSM) modem transfers the network data to a remote server located at the University of Freiburg

D5.1 SHM digital twin requirements for residential, industrial buildings and bridges

This deliverable presents a report of the needs for structural control on buildings (initial imperfections, deflections at service, stability, rheology) and on bridges (vibrations, modal shapes, deflections, stresses) based on state-of-the-art image-based and sensor-based techniques. To this end, the deliverable identifies and describes strategies that encompass state-of-the-art instrumentation and control for infrastructures (SHM technologies).Objectius de Desenvolupament Sostenible::8 - Treball Decent i Creixement EconòmicObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraPreprin

Open-source digital technologies for low-cost monitoring of historical constructions

This paper shows new possibilities of using novel, open-source, low-cost platforms for the structural health monitoring of heritage structures. The objective of the study is to present an assessment of increasingly available open-source digital modeling and fabrication technologies in order to identify the suitable counterparts of the typical components of a continuous static monitoring system for a historical construction. The results of the research include a simple case-study, which is presented with low-cost, open-source, calibrated components, as well as an assessment of different alternatives for deploying basic structural health monitoring arrangements. The results of the research show the great potential of these existing technologies that may help to promote a widespread and cost-efficient monitoring of the built cultural heritage. Such scenario may contribute to the onset of commonplace digital records of historical constructions in an open-source, versatile and reliable fashion.Peer ReviewedPostprint (author's final draft

Localization and detection of wireless embeddable structural sensors using an unmanned aerial vehicle in the absence of visual markers

The objective of this thesis is to develop a fully integrated UAV based platform for autonomous collection of data from embedded sensors. Passive (battery-less) embedded sensors provide means for periodic long-term monitoring of civil structures like bridges. However, collection of data from these sensors requires extensive manual effort of locating them. UAVs can automate this process, although localization of these embedded tags in absence of visual markers pose a challenge. A RF (13.56MHz) reader is used to capture data from RF tags wirelessly. Different tag coil sizes are tested to observe effects on read range as well as to characterize the interaction volume between reader and tag. The UAV platform is integrated with the RF reader to autonomously capture data from tags using GPS based localization. Different sensor configurations are tested and characterized to meet the requirements of X,Y,Z localization set by the reader and tag interaction volume. Flight characteristics are also observed for various UAV navigation parameters. Results suggest that by using low-cost RTK GPS unit, the UAV is capable of detecting and localizing RF tags without any visual markers or aides.Electrical and Computer Engineerin

Application of advanced non-destructive testing methods on bridge health assessment and analysis

Bridge structures have an important role in economic, social and environmental aspects of society life. Bridges are also subject to a natural process of deterioration of construction materials, as well as natural and environmental events such as flooding, freezing, thawing etc. Health monitoring and assessment of the structural integrity of bridges have been the focus of engineers and researchers for decades. Currently, the various aspects of bridge health are monitored separately. However, measuring these aspects independently does not give the overall health of the bridge and crucial indicators of structural damage can be neglected. Generally, bridge health assessments take the form of individual NDT (non-destructive techniques) detecting individual defects. However value can be added to these results by combining and comparing the findings of several different NDT surveys. By completing this, a more accurate assessment of bridge health is obtained. This increases confidence in the decision as to whether remedial action is necessary. In this thesis an integrated bridge health monitoring approach is proposed which applies several NDT specifically chosen for bridge health assessments, thus achieving this added value. This method can be used as a part of a comprehensive bridge monitoring strategy as an assessment tool to evaluate the bridges structural health. This approach enables the user of this approach to obtain a detailed structural report on the bridge with all the necessary information pertaining to its’ health, allowing for a fully educated decision to be made regarding whether remedial action is necessary. This research presents the results of the applications of such methods on case studies utilising Ground Penetrating Radar (GPR), IBIS-S technology / system (deflection and vibration detection sensor system with interferometric capability) and Accelerometer sensors. It also evaluates the effectiveness of the adopted methods and technologies by comparing and validating the yielded results with conventional methods (modelling and visual inspection). The research presents and discusses processed data obtained by the above mentioned methods in detail and reports on challenges encountered in setting up and materialising the assessment process. This work also reports on Finite Element Modelling (FEM) of the main case study (Pentagon Road Bridge) using specialist software (SAP2000 and ANSYS) in order to simulate the perceived movement of the bridge under dynamic and static conditions. The analytical results output were compared with results obtained by the applications of the above non-destructive methods. Thus by using these techniques the main aim of this thesis is to develop an integrated model/approach for the assessment and monitoring of the structural integrity and overall functionality of bridges. All the above methods were validated using preliminary case studies (GPR), additional equipment (accelerometers for IBIS-S validation) and additional techniques and information (SAP 2000 and ANSYS were compared to one another and IBIS-S results). All of these techniques were applied on the Pentagon Road Bridge. This bridge was chosen as no information was available regarding its structural composition. Visual inspection showed the external defects of the structure: cracking, moisture ingress and concrete delamination was present in one of the spans of the bridge. The GPR surveys gave the position of the rebars and also signs of moisture ingress at depths of 20cm (confirmed using velocity analysis). IBIS-S gave results for the deflection of the structure. FEM was used to model the behaviour of the bridge assuming no defects. To achieve additional model accuracy the results of the rebar position were input in to the model and it was calibrated using IBIS-S data. The deflection results from the model were then compared to the actual deflection data to identify areas of deterioration. It was found that excessive deflection occurred on one of the spans. It was thus found that all NDT indicated that a particular span was an area of significant deterioration and remedial action should be completed on this section in the near future. Future prediction was also completed by running simulations in ANSYS for increasing crack lengths and dynamic loading. It was found that if there is no remedial action excessive beam bending moments will occur and eventual collapse. The results of this research demonstrated that GPR provided information on the extent of the internal structural defects of the bridge under study (moisture ingress and delamination) whilst IBIS-S technology and Accelerometer sensors permitted measurement of the magnitude of the vibration of the bridge under dynamic and static loading conditions. The results depicted similarities between the FEM results and the adopted non-destructive methods results in location and pattern. This work can potentially contribute towards a better understanding of the mechanical and physical behaviours of bridge structures and ultimately assess their life expectancy and functionality