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 ere rapidly increasing, and these needs stimulated developments of new 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 and temperature changes and
cracks. Such a sensor is therefore able to record one-dimensional strain field and can be installed over the
whole length of the structural members to be monitored (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. These sensors
are therefore not only able to measure strain (answering the “how much” question) but to localize damage
areas (answering the “where” questions). This makes them ideal to monitor structure where the location of
possible damage is a-priori unknown. As an example the sensor can detect and localize a fatigue crack appearing
on a bridge girder or a leakage in a pipeline. Distributed sensing techniques and components based on
Brillouin and Raman scattering are briefly introduced and their potential for integrity monitoring is discussed.
Finally, several large-scale application examples are presented, including crack detection on steel girders, leakage
detection on pipelines and crack localization in a tunnel.