Numerical insight on the interaction effects of a confined masonry tower

The present paper provides a numerical insight into the structural behavior of a confined masonry tower. The study is carried out in relation to the Gabbia Tower, the tallest historical masonry tower in the city of Mantua (northern Italy), which is surrounded by multistory masonry buildings on all its sides. Three 3D FE numerical models are critically compared to investigate the sensitivity of the structural behavior of the tower with respect to the adjacent buildings, both in the linear and non-linear fields. Firstly, the tower is studied as a fictitious building isolated from the context, then two different constraints are considered for modeling the interaction between tower and buildings. In the first case, linear elastic springs are inserted along the height of the tower; while the other one focuses on the effect provided by the adjacent buildings, whose walls are modeled as monolithic elements joined to the main body of the tower. The validation of the FE models is carried out in the linear field by comparing mode shapes and frequencies resulting from the numerical modal analysis with the available experimental data provided by the ambient vibration test conducted in 2012. The effect of the different constraints on the seismic response of the tower is then investigated by performing a set of non-linear dynamic analyses and considering the accelerograms recorded during the earthquake of May 29, 2012 by the fixed station located in Mantua as seismic input. Numerical results indicate the modeling of the surroundings as an essential step for a realistic analysis of confined towers. In particular, the simulations highlight advantages and limitations of the proposed modeling approaches of the constraints, both in the linear and non-linear fields.