Direct Damage Detection Using Advanced Sensing Technologies

Abstract

Civil structures and infrastructure in use are aging, deteriorating and eventually approaching the end of their lifespan. It is necessary to determine and monitor their structural health in order to mitigate risks, prevent disasters, and plan maintenance activities in an optimized manner. Thus reliable, low-cost, and easy-to-adopt structural health monitoring (SHM) is in an immediate and urgent need in order to accurately assess the state and improve the safety of the structures, and set priorities for allocating funds for maintenance and repair.

However, SHM is not applied in a widespread or generic manner. The main reason for this is the lack of reliable and affordable monitoring solutions. Today’s technologies give infrastructure managers access to sparsely spaced sensors. These, unfortunately, do not allow reliable early detection of anomalies such as strain concentrations or cracks at locations of even modest distance from the sensors. Such forms of indirect damage detection thus require complex algorithms whose reliability is challenged by practical noise sources, such as temperature variations, precipitation, and normal variability in loading conditions.

In order to address above challenges, the thesis proposes direct damage detection principles based on two advanced technologies, which are Distributed Fiber Optic Sensors (DFOS) and Large Area Electronics (LAE). DFOS can be represented by a single cable that is sensitive at every point along its length, which is applicable in one-dimensional (1D) damage detection. LAE is an emerging technology that allows a broad range of sensors and electronics to be integrated on low-cost plastic sheets, which can be considered as a two-dimensional (2D) quasi-distributed sensor. The objectives of this research are two-fold: to investigate direct sensing-system principles that provide affordable monitoring through a dense and expansive array of sensors enabled by DFOS and LAE technologies; and to experimentally study how the high-resolution sensing offered by such systems can overcome the robustness and reliability limitations affecting current SHM technologies. The main concepts are presented in the thesis along with both reduced and large-scale test results, which demonstrate that the proposed technologies and direct sensing approach are feasible and beneficial for reliable damage detection and localization over large areas of structures.