Civil Engineering Association

A STUDY ON SEISMIC BEHAVIOUR OF MASONRY TOWERS

This study is dedicated to simplified vulnerability assessment of
masonry towers, in particular to the definition of collapse mechanism geometry.
After a preliminary analysis on damages and collapse mechanisms
caused to towers by the earthquakes and a review of analysis
methods in literature, a model to determine the plane of fracture that defines the kinematic blocks of an overturning mechanism was proposed, based on simple equilibrium conditions.
According to the Italian codes, in fact, tower structures are classified as one of the churches macroelements, characterized by peculiar collapse mechanisms; respect to other macroelements, for towers a slight variation in mechanism geometry implies relevant variation in collapse multiplier values; this is mainly due to the importance of mass and height in these structures. Hence a correct definition of kinematism geometry results very important.
The proposed method was applied also including a limit on masonry compressive strength, despite traditional limit analysis method that usually assumes as infinite masonry compressive strength.
For the use in common practice, the curve of fracture was evaluated through parametric analyses for different geometrical configurations, to which many existing towers can be assimilated. Finally, besides a comparison with real collapse mechanisms surveyed on towers after earthquakes, the proposed method was applied also in the vulnerability assessment of a medieval masonry tower, the Ghirlandina in Modena.

A STUDY ON SEISMIC BEHAVIOUR OF MASONRY TOWERS