Status and remaining challenges of vibration-based Structural Health Monitoring
Prof. Guido De Roeck
KU Leuven Monday
February, 3rd
h. 10:00-13:00
Room 0.7 (viale Risorgimento 2, Bologna)
Abstract: Vibration-based Structural Identification has become an increasingly popular experimental technique, e.g. for model calibration, control of structural behavior during construction, assessment of the efficiency of structural repair, …
Main breakthrough was the development of operational modal analysis (OMA), avoiding the use of artificial vibration sources. Vibration-based Structural Health Monitoring is based on the principle that modal parameters of a structure are stiffness dependent. Changes in natural frequencies, damping ratios, mode shapes or combinations can therefore be used as features to detect and to identify damage.
A particular challenge is the discovery of small local damage. In this regard, directly measuring (modal) strains has a high potential. Very promising results on laboratory beams as well real bridges are obtained by an optical FBG strain sensor network that can cope with the very low strain intensities during operational conditions.
Non model-based methods try to identify damage from a comparison of pure measurements (or features directly derived from them) before and after a damaging event without relying on a (numerical) model. In most cases only the first (alarm) level of damage can be reached.
The advantage of model-based methods is that they can go further in the damage identification process. They intend to localize and to quantify the damage. Disadvantage is the need to construct a reliable model. Damage identification is accomplished through a FE-model updating process, minimizing differences between measured and calculated modal parameters. It is shown that the addition of modal strains to the objective function of the minimization problem improves the damage identification process.