The health state of a structural beam as a flexural member can be evaluated by the curvature or flexural strain. Measured strain data provide more accurate flexural characteristics than the curvature approximation by the central difference method from the displacement mode shape and DFRFs (displacement frequency response functions). The strain sensor may be sensitive to local damage when analyzing the flexural response. This work presents a method to detect damage utilizing only the measured strain data collected from a damage-expected beam structure without intact baseline data. The static method from the measurement strain data and the dynamic method from measured SFRFs (strain frequency response functions) are introduced. It can be observed that damage exists in the region, which represents an abrupt change in the strain response. The validity of the method is illustrated by numerical and experimental applications
