Seismic Assessment of Masonry Towers by Means of Nonlinear Static Procedures

The paper presents some FE analyses conducted through advanced techniques for the seismic assessment of existing masonry towers. Traditionally, masonry towers were conceived to withstand vertical loads only, but in recent years national and international standards have imposed the evaluation of their structural performance even in presence of horizontal forces. Eight towers are chosen deliberately very different in geometry and a number of linear and non-linear structural analyses are performed. Their behavior under horizontal loads (mimicking earthquake actions) is investigated by means of traditional static nonlinear procedures. Modal participations in pushover analyses are considered in order to have an insight into the role played by the higher modes in the local and global behavior of the structure. A non-conventional pushover approach, hereafter called EPA-Extended Pushover Analysis-based on modal combinations is utilized. Some comparative analyses between standard and non-conventional pushover are reported. It is found that EPA is reasonable when the contribution of higher modes is significant. EPA turns out to have a reasonable resemblance in terms of capacity and deformation pattern with non-linear dynamic results, highlighting the significant role of the higher modes in such structures, where for instance the presence of the bell cell can play a certain role. Further vulnerability considerations for the towers deduced by the performed analyses are also reported.