Design and Validation of a Real-Time Structural Health Monitoring System Interfacing Through a Local Area Network

Civil Infrastructure Systems (CIS) are a major societal investment, yet CIS rarely employs advanced evaluation and diagnostic technologies. As a result, many forms of structural damage are not intercepted in their early stages or are obscured altogether. This reality has driven the development of automated, unattended diagnostic capabilities broadly categorized as Structural Health Monitoring (SHM). In addition to the improved assessment capabilities, the full-scale data collected via SHM has been used as a means to verify in-situ performance of complex structures to validate the models and assumptions used in their design. Long-term evaluations can also underscore the effects of aging and the performance of the structure under significant events. One of the primary deterrents to SHM deployments is the cost associated with installation, specifically the running of lengthy cables to connect the sensors to the data acquisition system in the traditional 'hub and spoke' architecture. As a result, extensive research into wireless sensor networks has evolved, though multi-hop relays, packet loss and power constraints have limited their practical utility. This project offers an alternative form of data acquisition for buildings using existing local area networks to offer much of the flexibility of the wireless system without the packet loss, synchronization and power issues. The proposed SHM concept emulates a traditional centralized data acquisition system but replaces lengthy cable runs with the existing Ethernet systems within the building to form a 'virtual' network of instrumentation cables. The resulting network-enabled SHM system is less expensive and easier to install than traditional wired systems, making it easily scalable. Furthermore, the system is more reliable and sustainable than wireless systems, drawing both its power and communications paths from the existing infrastructure of the building. Given the speed and reliability of modern Internet connections, with appropriate security measures, this SHM system delivers a cost-effective means to quickly procure data and share it with end users in real-time without a direct connection between the data acquisition system and the sensing element. This thesis focuses on the prototyping and validation of the hardware necessary to achieve this network-enabled 'virtual' wireless system, including the various digital response-sensing elements that will interface with the network. Specific objectives are: (1) the validation of digital sensing elements, (2) prototyping of a 'virtual' wireless SHM system that includes a digital and analog accelerometer, GPS and meteorological station, (3) development and evaluation of a companion system that permits direct interface of digital sensors to the local area network and (4) full-scale installation and evaluation of the GPS components for network-enabled real-time monitoring. This research ultimately confirms the viability of 'virtual' wireless structural health monitoring using local area networks, offering a cost effective, scalable and reliable alternative to wired sensing.