G. Camata, L. Cifelli, E. Spacone, J. Conte, Maurizio Loi and P. Torrese
"This paper presents the results of seismic vulnerability assessment of an ancient tower erected in the XIV century and located in Guardiagrele, Chieti province (Italy). An extensive in situ experimental campaign was conducted to identify the material properties and the geometry of the tower as well as the stratigraphy of the supporting soil. The tower natural frequencies and mode shapes are extracted from ambient vibration data using state-of-the-art system identification techniques. The onsite investigation results are used to calibrate the elastic properties of the 3D finite element model (FEM) of the tower developed using the commercial programs ABAQUS v. 6.5.1 (ABAQUS inc. 2005) and MIDAS Gen, v. 7.21 (MIDAS, 2006). The foundation soil is modeled explicitly in order to study the soil-foundation structure interaction effects. A damage-coupled plasticity model is used the tower masonry. Results to date indicate that the response of the tower is greatly influenced by the frequency content of the input ground motion used in the Nonlinear Time History Analyses (NLTHA). The results are also very sensitive to the material properties used, and in particular to the selected damage evolution parameters."