Seismic damage identification by fitting the nonlinear and hysteretic dynamic response of monitored buildings

The identification of hysteretic degrading systems exposed to nonstationary loading is a paramount research topic, especially in the case of structures subjected to ground motion excitations. In this paper, the data recorded by a masonry building are used to detect the presence of seismic damage. To this aim, a parametric nonlinear identification is performed by adopting a Bouc–Wen-type multiple oscillator model. Starting from the results of the identification process, a damage index based on the degrading stiffness matrix is defined. The damage index provides preliminary information to be used in post-event management. Finally, the identification procedure is applied to a monitored masonry structure, the Town Hall of Pizzoli (L’Aquila), which is part of the Italian Seismic Observatory of Structures (OSS). The records measured by accelerometers permanently installed on the building are used for the detection of damage occurred during a seismic event.