Wireless Sensor Networks for Monitoring Cracks in StructuresPublic Deposited
Autonomous Crack Monitoring (ACM) and Autonomous Crack Propagation Sensing (ACPS) are two types of structural health monitoring in which characteristics of cracks are recorded over long periods of time. ACM seeks to correlate changes in widths of cosmetic cracks in structures to nearby blasting or construction vibration activity for the purposes of litigation or regulation. ACPS seeks to track growth of cracks in steel bridges, supplementing regular inspections and alerting stakeholders if a crack has grown. Both ACM and ACPS may be implemented using wired data loggers and sensors, however, the cost of installation and intrusion upon the use of a structure makes the use of these systems impractical if not completely impossible. This thesis presents the implementation of these systems using wireless sensor networks (WSNs) and evaluates the effectiveness of each. Three wireless ACM test deployments are presented: the first a proof of concept, the second to show long-term functionality, and the third to show the effectiveness of a newly invented device for low-power event detection. Each of these case studies was performed in a residential structure. Four laboratory experiments of ACPS systems and sensors are presented: the first three show the functionality of commercially available crack propagation sensors and a WSN system adapted from the agricultural industry. The final experiment shows the functionality of a newly invented form of crack propagation gage that allows for a more flexible installation of the sensor.
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