Pushover analysis for seismic assessment of masonry towers

Seismic assessment of age-old masonry towers or similar slender towers such as minarets is a priority in structural engineering, as such structures represent a large part of the cultural heritage of the Mediterranean basin. This paper examines the suitability of applying non-linear static methods based on pushover analysis for predicting the dynamic response of such structures. To this aim, the accuracy of both force- and displacement-controlled pushover analyses is evaluated by comparing their predictions of the values of some local and global parameters related to damage with those obtained through dynamic analyses. The study is conducted using a numerical model recently developed by the authors and implemented in the computational code MADY, which enables easily performing non-linear analyses of slender structures while taking into account the mechanical and geometrical non-linearities of masonry’s behaviour. The results of a structural case study suggests that the force-controlled procedure does not always provide satisfactory results. Although this pushover procedure offers good predictive capacity in terms of displacements, total base shear and localized damage at the tower base, it fails to accurately predict global damage, especially for high-level seismic hazards. Conversely, when the analysis is conducted through a displacement-controlled procedure, the damage estimates over the full height of the tower are much more accurate than those provided by force-controlled analysis.