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

INE/AUTC 10.0

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

Wireless Monitoring Systems for Long-Term Reliability Assessment of Bridge Structures based on Compressed Sensing and Data-Driven Interrogation Methods.

The state of the nation’s highway bridges has garnered significant public attention due to large inventories of aging assets and insufficient funds for repair. Current management methods are based on visual inspections that have many known limitations including reliance on surface evidence of deterioration and subjectivity introduced by trained inspectors. To address the limitations of current inspection practice, structural health monitoring (SHM) systems can be used to provide quantitative measures of structural behavior and an objective basis for condition assessment. SHM systems are intended to be a cost effective monitoring technology that also automates the processing of data to characterize damage and provide decision information to asset managers. Unfortunately, this realization of SHM systems does not currently exist. In order for SHM to be realized as a decision support tool for bridge owners engaged in performance- and risk-based asset management, technological hurdles must still be overcome. This thesis focuses on advancing wireless SHM systems. An innovative wireless monitoring system was designed for permanent deployment on bridges in cold northern climates which pose an added challenge as the potential for solar harvesting is reduced and battery charging is slowed. First, efforts advancing energy efficient usage strategies for WSNs were made. With WSN energy consumption proportional to the amount of data transmitted, data reduction strategies are prioritized. A novel data compression paradigm termed compressed sensing is advanced for embedment in a wireless sensor microcontroller. In addition, fatigue monitoring algorithms are embedded for local data processing leading to dramatic data reductions. In the second part of the thesis, a radical top-down design strategy (in contrast to global vibration strategies) for a monitoring system is explored to target specific damage concerns of bridge owners. Data-driven algorithmic approaches are created for statistical performance characterization of long-term bridge response. Statistical process control and reliability index monitoring are advanced as a scalable and autonomous means of transforming data into information relevant to bridge risk management. Validation of the wireless monitoring system architecture is made using the Telegraph Road Bridge (Monroe, Michigan), a multi-girder short-span highway bridge that represents a major fraction of the U.S. national inventory.PhDCivil EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/116749/1/ocosean_1.pd

Development of Local and Global Corrosion Sensing Technique to Monitor Structural Behavior of Prestressed Concrete Structures

Corrosion of steel rebar in reinforced concrete structures is a concern for highway bridge owners. According to 2002 study by the Federal Highway Administration, ~15% of the highway bridges in the US are structurally deficient due to corrosion and have an estimated annual direct cost of $8.3 billion. Generally, in post-tensioned bridges, ducts filled with poor or incomplete grouting can allow the tendons to come into contact with water, leading to corrosion and fracture. Although new and improved procedures of grouting have been developed to reduce the instances of poor grouting, the problem of how to reliably inspect tendons on existing structures remains. This research aimed to evaluate the feasibility of using currently available local and global corrosion sensing techniques to monitor the performance of concrete structures. This dissertation explores the use of three local corrosion sensors (resistivity sensors, relative humidity sensors, and resistor-inductor- capacity [RLC] sensors). In this research, local sensors (i.e. RH sensors and four-point resistivity sensors) placed at an interval of every three foot were able to detect corrosion conducive environment in PT ducts by measuring the electrical properties and moisture contents of the grout. However, the measured RH was consistently lower in the low point of the specimens compared to the high points for all the specimens. The four-point resistivity sensors were able to detect a clear difference between the grouted ducts with good grout compared to ducts with chloride-rich grout with voids and layered-chloride rich grout without voids. To evaluate destructive testing and monitor the global response, two full-scale prestressed concrete inverted-tee (IT) beams were constructed and instrumented with vibrating wire strain gauges (VWSGs) located in multiple planes along the length. The VWSGs were able to clearly detect the initiation of corrosion in the first prestressing strand in each beam. The local corrosion damage in the first strand resulted in a change in the behavior of the beam, which was detected by the VWSGs (through a change in slope of curvature versus time)

Roadmap on measurement technologies for next generation structural health monitoring systems

Structural health monitoring (SHM) is the automation of the condition assessment process of an engineered system. When applied to geometrically large components or structures, such as those found in civil and aerospace infrastructure and systems, a critical challenge is in designing the sensing solution that could yield actionable information. This is a difficult task to conduct cost-effectively, because of the large surfaces under consideration and the localized nature of typical defects and damages. There have been significant research efforts in empowering conventional measurement technologies for applications to SHM in order to improve performance of the condition assessment process. Yet, the field implementation of these SHM solutions is still in its infancy, attributable to various economic and technical challenges. The objective of this Roadmap publication is to discuss modern measurement technologies that were developed for SHM purposes, along with their associated challenges and opportunities, and to provide a path to research and development efforts that could yield impactful field applications. The Roadmap is organized into four sections: distributed embedded sensing systems, distributed surface sensing systems, multifunctional materials, and remote sensing. Recognizing that many measurement technologies may overlap between sections, we define distributed sensing solutions as those that involve or imply the utilization of numbers of sensors geometrically organized within (embedded) or over (surface) the monitored component or system. Multi-functional materials are sensing solutions that combine multiple capabilities, for example those also serving structural functions. Remote sensing are solutions that are contactless, for example cell phones, drones, and satellites. It also includes the notion of remotely controlled robots

Bridge Structrural Health Monitoring Using a Cyber-Physical System Framework

Highway bridges are critical infrastructure elements supporting commercial and personal traffic. However, bridge deterioration coupled with insufficient funding for bridge maintenance remain a chronic problem faced by the United States. With the emergence of wireless sensor networks (WSN), structural health monitoring (SHM) has gained increasing attention over the last decade as a viable means of assessing bridge structural conditions. While intensive research has been conducted on bridge SHM, few studies have clearly demonstrated the value of SHM to bridge owners, especially using real-world implementation in operational bridges. This thesis first aims to enhance existing bridge SHM implementations by developing a cyber-physical system (CPS) framework that integrates multiple SHM systems with traffic cameras and weigh-in-motion (WIM) stations located along the same corridor. To demonstrate the efficacy of the proposed CPS, a 20-mile segment of the northbound I-275 highway in Michigan is instrumented with four traffic cameras, two bridge SHM systems and a WIM station. Real-time truck detection algorithms are deployed to intelligently trigger the SHM systems for data collection during large truck events. Such a triggering approach can improve data acquisition efficiency by up to 70% (as compared to schedule-based data collection). Leveraging computer vision-based truck re-identification techniques applied to videos from the traffic cameras along the corridor, a two-stage pipeline is proposed to fuse bridge input data (i.e. truck loads as measured by the WIM station) and output data (i.e. bridge responses to a given truck load). From August 2017 to April 2019, over 20,000 truck events have been captured by the CPS. To the author’s best knowledge, the CPS implementation is the first of its kind in the nation and offers large volume of heterogeneous input-output data thereby opening new opportunities for novel data-driven bridge condition assessment methods. Built upon the developed CPS framework, the second half of the thesis focuses on use of the data in real-world bridge asset management applications. Long-term bridge strain response data is used to investigate and model composite action behavior exhibited in slab-on-girder highway bridges. Partial composite action is observed and quantified over negative bending regions of the bridge through the monitoring of slip strain at the girder-deck interface. It is revealed that undesired composite action over negative bending regions might be a cause of deck deterioration. The analysis performed on modeling composite action is a first in studying composite behavior in operational bridges with in-situ SHM measurements. Second, a data-driven analytical method is proposed to derive site-specific parameters such as dynamic load allowance and unit influence lines for bridge load rating using the input-output data. The resulting rating factors more rationally account for the bridge's systematic behavior leading to more accurate rating of a bridge's load-carrying capacity. Third, the proposed CPS framework is shown capable of measuring highway traffic loads. The paired WIM and bridge response data is used for training a learning-based bridge WIM system where truck weight characteristics such as axle weights are derived directly using corresponding bridge response measurements. Such an approach is successfully utilized to extend the functionality of an existing bridge SHM system for truck weighing purposes achieving precision requirements of a Type-II WIM station (e.g. vehicle gross weight error of less than 15%).PHDCivil EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/163210/1/rayhou_1.pd

Development of an autonomous system for assessment and prediction of structural integrity

Kako bi se osiguralo racionalnije, plansko održavanje prometne infrastrukture uz smanjenje troškova te u konačnici minimalizirao rizik od katastrofalnih posljedica, nužan je razvoj inovativnih rješenja u području održavanja građevina prometne infrastrukture. Kroz projekt ASAP razvija se sustav za autonomni pregled građevina, koji se zasniva na naprednim mjernim metodama integriranim na robota penjača i bespilotnu letjelicu. Cilj ovog rada je dati osvrt i upozoriti na nedostatke konvencionalnog načina ispitivanja materijala i konstrukcija za potrebu ocjene stanja, koji su bili osnovna motivacija okupljanja multidisciplinarnog tima kroz projekt ASAP. U radu su također prikazane mogućnosti i izazovi razvoja autonomnog sustava za pregled građevina, a sve u svrhu povećanja pouzdanosti i efikasnosti sustavnog pregleda građevina.Development of innovative solutions for the maintenance of transport infrastructure facilities is needed in order to ensure a more rational, planned and lower-cost maintenance of transport infrastructure, and to ultimately minimise the risk of catastrophic consequences. A system for an autonomous inspection of structures, based on advanced measuring methods integrated on a wall-climbing robot and an unmanned aerial vehicle, is currently developed in the scope of the ASAP project. The objective of this paper is to provide an overview and draw attention to disadvantages of conventional methods for testing materials and structures in order to assess their condition. This objective was the main motivation for forming a multidisciplinary team through the ASAP project. Possibilities and challenges in the development of an autonomous structural-assessment system are also presented in the paper, with the purpose of increasing the reliability and efficiency of systemic assessment of structures

Autonomous Corrosion Assessment of Reinforced Concrete Structures Feasibility Study

In this work, technological feasibility of autonomous corrosion assessment of reinforced concrete structures is studied. Corrosion of reinforcement bars (rebar), induced by carbonation or chloride penetration, is one of the leading causes for deterioration of concrete structures throughout the globe. Continuous nondestructive in-service monitoring of carbonation through pH and chloride ion (Cl−) concentration in concrete is indispensable for early detection of corrosion and making appropriate decisions, which ultimately make the lifecycle management of RC structures optimal from resources and safety perspectives. Critical state-of-the-art review of pH and Cl− sensors revealed that the majority of the sensors have high sensitivity, reliability, and stability in concrete environment, though the experiments were carried out for relatively short periods. Among the reviewed works, only three attempted to monitor Cl− wirelessly, albeit over a very short range. As part of the feasibility study, this work recommends the use of internet of things (IoT) and machine learning for autonomous corrosion condition assessment of RC structures. </p

Design and Modeling of a Soil-Based Energy Harvester for Underground Wireless Sensor Nodes

Wireless Sensor Networks (WSN) have emerged as a reliable and viable solution for monitoring complex large-scale strategic assets that are placed in harsh and hostile environments. Some of the major application areas include environmental monitoring, disaster management, infrastructure monitoring, and security. A large number of such infrastructures are buried underground and have a limited service life. It is important to assess their condition throughout their life cycle to avoid possible catastrophic failures due to their deterioration. Monitoring such infrastructures creates a complex wireless sensor network with thousands of sensor nodes that are required to be functional with zero maintenance for 10∼20 years once deployed. Powering such Wireless Sensors (WS) for decades is a key challenge in the design and operation of WSN. Sacrificial Anode Cathodic Protection (SACP) technique is a well-known technique for corrosion protection. In this technique, steel structures are protected from natural corrosion by enabling an externally connected anode material to deplete over time. To model the depletion rate of the anode for replacement purposes, human readers visit each Sacrificial Anode (SA) site to take voltage and current measurements once a month. This approach is expensive and prone to human errors. Moreover, there is a large number of such sites in a city. The main challenge in using WSN in such scenarios is providing a reliable source of energy to power the sensor nodes. As the majority part of the structure is buried underground, traditional renewable energy sources, such as solar, wind, and thermal do not offer any lucrative solution due to their requirements for additional setup, space, and periodic maintenance. Thus, an underground soil-based energy harvester using the existing setup has been carefully researched, designed, developed, and implemented as part of this research. The technique exploits the electric current flowing from the cathode to the anode to energize the sensor nodes. The prototype developed in the lab uses the harvested energy from soil to power sensor nodes to communicate the data to the cloud. To develop and implement the prototype two test benches were set up, one indoor and the other outdoor. The outdoor setup facilitated the experiments under varying weather conditions and with the indoor one, experiments were conducted under a controlled environment. The prototype developed in the lab will be buried underground for security purposes, as a result, data needs to be transmitted through the soil between nodes. Radio Frequency (RF) transmission through the soil is one of the main challenges for this project. Various parameters affect RF signal attenuation in soil (i.e. transmission frequency, burial depth, soil dielectric properties, etc.). In this research, we have investigated, tested and implemented several wireless technology modules such as Global System for Mobile Communications (GSM), Wireless Fidelity (Wi-Fi), Zigbee, Narrow Band-Internet of Things (NB-IoT) to meet the desired requirements. The research also outlines the complete operation of the developed module. In addition to that, to estimate the energy harvesting rate, energy harvesting efficiency and to analyze the charging behavior several experiments were conducted to obtain the Current-Voltage (I-V) and the Power-Voltage (P-V) characteristics of the energy source. This study is later used to develop a model for the energy source. The model is validated with measurement data from the field trials. This developed model is helpful to easily realize a system and can be useful to solve numerical problems, find information about operating point or to analyze a circuit