Structural health monitoring (SHM) is a process aimed at providing accurate and real-time information concerning structural condition and performance. Needs for structural health monitoring in the last decades were rapidly increasing, and these needs stimulated developments of various sensing technologies. Distributed optical fiber sensing technology has opened new possibility in structural monitoring. Distributed deformation sensor (sensing cable) is sensitive at each point of its length to strain changes and cracks. Such a sensor practically monitors one-dimensional strain field andcan be installed over all the length of the monitored structural members (suspension cables, bridge girders, tunnel vaults, dam basis, etc.), and therefore provides for integrity monitoring, i.e. for direct detection, characterization (including recognition, localization, and quantification or rating), and report of local strain changes generated by damage. Integritymonitoring principle for long bridges and tunnels is developed and presented in this paper. Various distributed sensing techniques are summarized and their potential for the use in integrity monitoring is compared. Finally, the first large scale real on-site application is briefly presented.
Abstract