Fiber optic strain sensors have significantly evolved and have reached their market maturity during the last decade. Their widely recog- nized advantages are high precision, long-term stability, and durability. In addition to these benefits, fiber optic (FO) techniques allow for affordable instrumentation of large areas of civil structures and infrastructure ena- bling global large-scale monitoring based on long-gauge sensors, and integrity monitoring based on distributed sensors. The FO techniques that enable these two approaches are based on fiber Bragg-gratings and Brillouin optical time-domain analysis. The aim of this paper is to present both FO techniques and both structural assessment approaches, and to validate them through large-scale applications. Although many other currently applied methods fail to detect the damage in real, on-site conditions, the presented approaches were proven to be suitable for dam- age detection and characterization, i.e., damage localization and, to cer- tain extent, quantification. This is illustrated by two applications presented in detail in this paper: the first on a post-tensioned concrete bridge and the second on segmented concrete pipeline. © 2013 Society of Photo-Optical