SEISMIC ASSESSMENT OF A MEDIEVAL MASONRY TOWER IN THENORTHERN ITALY: FULL NON-LINEAR STATIC AND DYNAMIC ANALYSES

In the present paper, a comparative numerical study on a medieval masonry tower located in the northern Italy is described. To assess the safety of the tower under seismic loads, several pushover, limit and non-linear dynamic analyses are performed. In the first two cases, a full 3D detailed FE model is adopted, changing the seismic load direction and assuming different hypotheses for the interconnection between the core and the external walls. When dealing with the FEM incremental analysis, a commercial code is utilized assuming for masonry a smeared crack isotropic model. In the latter case, a simplified 2D RBSM (Rigid Body and Spring Model) schematization is utilized, accounting for the asymmetries along the thickness and the irregularities changes of thickness of both the external and internal walls in an approximate but realistic way. Four different accelerograms are utilized –passing representative of low and high seismicity zones- to assess the safety of the tower under dynamic loads. From numerical results, the role played by the actual geometry of the tower is envisaged, as well as a detailed comparison of failure mechanisms provided by the incremental FEM and limit analysis is provided. In all cases, the numerical analysis has given a valuable picture of possible damage mechanisms providing useful hints for the introduction of structural monitoring.