Parameter estimation method for damage detection in torsionally coupled base-isolated structures

An extended Kalman filter methodology has been developed and tested to make the real time identification of the elemental stiffness of a base isolation system and to detect the damage starting from acceleration measurements. Base isolation is widely adopted to mitigate earthquake effects on structures. Information concerning the status of the isolation devices is fundamental, for example, after an emergency event and, consequently, damage detection procedures have received significant attention in the recent years. Simulations have been carried out by means of a three degree of freedom model and results are illustrated. Moreover, experimental evaluations of the damage detection method have been conducted by means of a prototype structure that has been excited adopting a sequence of seismic events. The results highlight a stiffness degradation and fully agree with the measurements, allowing a validation of the technique. Furthermore, the analytically simulated accelerations, obtained by means of the instantaneously identified values of the stiffness, fully agree with the measured accelerations, highlighting the accuracy of the identification procedure.