Development of Structural Health Monitoring System by using Distributed Optical Fiber Sensing

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Structural hearth monitoring (SHM) has become one of the most particular concerns of infrastructure engineering community worldwide. Implementation of successful SHM programs requires selection and placement of sensors suitable for measurement of key parameters that influence the performance and health of the structural system. Fiber optic sensors provide flexibility and practicality in many situations, where the conventional sensors are either not capable of feasible to make the appropriate measurements. Furthermore, fiber optic sensors are capable for making distributed measurements and can be serially multiplexed and this in turn reduces the number of leads running through structures. Many fiber optic sensor types and configurations have become available over the past two decades, including localized, long gauge and distributed sensors. The establishment of SHM systems based on distributed and serially multiplexed fiber optic sensing technologies for large size of structures and div … More ersity of construction materials is an intense subject with great anticipation. This study is devoted in developing some key sensing, damage characterization and diagnostic methods for SHM of infrastructure such as concrete structures based on distributed and serially multiplexed fiber optic sensing technologies. It can be summarized as follows :1)The measurement principles and characteristics of strain & cracking distributions for brilliouin scattering based distributed sensing (BOTDR etc.) are investigated and examined clearly. Moreover, some effective installation approaches to improve the spatial resolution and accuracy and to filter the measurement noise are proposed in this study. On the other hand, a distributed sensing approach based on serially multiplexed FBG sensor is also proposed in which the FBG sensors are designed as a long-gauge manner with a variable gauge length.2)Distributed and remote monitoring both for static and dynamic responses of different types of structures including FRP-strengthened PC girder and beam-column assembly based above proposed distributed fiber optic sensing methods are investigated and discussed.3)Some kinds of distributed damage characterization methods based on neural networks and nonlinear FEM for frame, bridge and concrete tunnel linings with complex nonlinearity or crack distribution are proposed. Moreover, some attempts of developing the corresponding sensing-computational-diagnostic systems are made also in the study. Less