System Identification of a Two-Story Infilled RC Building in Different Damage States

This study focuses on vibration-based system identification of an actual structure located in El Centro, California. The structure had already been subjected to four earthquakes with epicenters in close proximity and was to be demolished due to the extended damage. Four damage levels were introduced to the structure by gradually removing four perimeter infill walls. A series of dynamic tests were conducted in each damage state using an eccentric mass shaker. The ambient vibration of the structure was also recorded through an array of 60 accelerometers mounted on the structure. The system identification discussed in this paper was conducted using the ambient vibration recordings. Moreover, a preliminary finite element model of the building was created to estimate numerically the dynamic characteristics of the structure. These were compared to the properties obtained from the system identification. The results indicate that the frequencies estimated by the model overestimate those obtained from the system identification results, while the experimentally and numerically obtained mode shapes are in good agreement.