The Impulse Excitation Technique (IET) is a useful tool for characterizing the structural condition of concrete.
Processing the obtained dynamic parameters (damping ratio, response frequency) as a function of response amplitude,
clear and systematic differences appear between intact and cracked specimens, while factors like age and sustained load
are also influential. Simultaneously, Acoustic Emission (AE) and Ultrasonic Pulse Velocity (UPV) techniques are used
during the three point bending test of the beams in order to supply additional information on the level of damage
accumulation which resulted in the specific dynamic behavior revealed by the IET test.
Fatigue assessment includes estimation of the expected damage accumulation and the remaining life-time of the
structure. This work is based on output-only vibration measurements at a limited number of locations provided by a
sensor network installed on the structure. For the fatigue damage assessment, the stress time responses are obtained by
using the vibration sensor data and a modal expansion approach enabling predictions of stresses at positions where
sensor installation is not possible. A methodology for the prediction of stresses based on the combination of a finite
element numerical model and the accelerations recorded at measurement locations is presented in this paper.