Strain Modal Analysis

One-year operational modal analysis of a steel bridge from high-resolution macrostrain monitoring: Influence of temperature vs. retrofitting

“…Strain mode shapes are an attractive alternative for the conventional displacement mode shapes [30,31], because modal strains and strain-based features [32,33] are much more sensitive to local damage than modal displacements [34], and dense sensor grids can be achieved at relatively low cost [35], thanks also to the multiplexing capacity of some sensor types such as fiber Bragg gratings (FBG) [36]. The main challenge has been that the dynamic strains that occur in large civil structures in operational conditions are very small, typically in the sub-microstrain range.…”

Vibration-based monitoring of an FRP footbridge with embedded fiber-Bragg gratings: Influence of temperature vs. damage

“…The main disadvantage is that a dense sensor grid is required for good damage localization capabilities [22], which is generally costly when conventional sensors, such as accelerometers, are employed. Strain mode shapes are an attractive alternative for the conventional displacement mode shapes [30,31], because modal strains and strain-based features [32,33,34] are much more sensitive to local damage [35] and dense sensor grids can be achieved at relatively low cost [36], thanks to the multiplexing capacity of some sensor types such as fiber-Bragg gratings (FBG) [37]. FBGs are used for monitoring of civil infrastructure, such as wind turbines [38] and bridges [6].…”