Global and Local Structural Health Monitoring Methods Based on Wireless Telemetry and Boundary-based Thermography

Our nation’s economy is dependent upon its transportation system for the movement of people, goods and services. Infrastructure plays a vital role in supporting transportation services. Given their importance, structures must be maintained to offer safe and reliable operations over extended life-cycles. Structural health monitoring (SHM) has emerged to offer owners a quantitative approach to monitoring structures, assessing system performance and estimating structural conditions. While SHM systems have been successfully deployed to structures, their full potential has not been reaped due to the gap that exists between SHM data and the decision-making needs of owners. This thesis contributes to the field by bridging this gap through two approaches. First, the thesis explores the advancement of wireless monitoring systems whose instrumentation strategy is defined by the needs of the decision-making process of the owner. This is illustrated in the thesis by exploring wireless monitoring systems and associated data-to-decision (D2D) frameworks in the United States Coast Guard (USCG) high-speed aluminum Response Boat-Medium (RB-M) and in the Harahan Bridge. In the former, the wireless hull monitoring system is tailored to derive RB-M hull response data over a short-period to create relationships between the environmental and operational conditions (EOC) of the vessel and the accumulation of fatigue in a critical hull component. In doing so, the vessel owner can make life-cycle decisions centered on managing fatigue accumulation by considering the future operational profile of the vessel. In the latter application, a wireless monitoring system is installed on the Harahan Bridge (which is a steel truss railroad bridge) to monitor bridge responses to triggered load events including trains, collisions, and earthquakes. Again, a fatigue critical eyebar element is considered with an alerting framework created to alert the bridge owner of overloading conditions that can accelerate fatigue accumulation. While the two case studies showcase clear benefits to designing wireless monitoring systems around the decision-making of the asset owner, they also highlight the value of local structural measurements for component health assessment. To extend the benefits offered by local sensing further, the thesis explores the creation of a cost-effective approach to damage detection through thermal conduction. Using point heaters and temperature sensors, a thermal-based computed tomography (CT) image reconstruction method is developed for two-dimensional (2D) mapping of structural conditions. This powerful local damage imaging method is implemented using a wireless impedance analyzer developed for use in structural wireless monitoring systems. In summary, a new approach to designing SHM systems is developed that looks first at the desired outcome, or decision that the data should inform. This is showcased in two unique wireless monitoring system and D2D framework studies. Next, a novel thermal imaging technique is proposed and validated. Lastly, a first-of-its-kind multi-functional wireless impedance analyzer is developed that is capable of enabling the wireless and permanent installation of multiple spatial sensing techniques.PhDCivil EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/138654/1/nephi_1.pd