Masonry towers constitute a huge amount of the Italian built heritage. For this reason, their safety assessment against earthquakes appears of very relevant societal importance. They are unique architectural typologies, usually conceived in ancient time exclusively to withstand vertical loads. On the other hand, the recent national and international norms encourage the use of sophisticated non-linear methods, to have a deep insight into the actual ultimate behavior of this kind of structures in the presence of strong horizontal excitations. In the present paper, belonging to a wider research project still in progress and aimed at the seismic analysis of several masonry towers in the Northern Italy, some existing masonry towers, differing from one another for the thickness of the perimeter walls, the height, percentage of perforations, are analyzed by means of a 2D non-linear dynamic code. The code is based on a relatively refined 2D discretization of the towers, obtained through rigid quadrilateral elements interconnected by non-linear axial and shear springs, exhibiting softening and energy dissipation under cyclic loads. Starting from a detailed survey of the structures and from the knowledge of the mechanical properties of the constituent materials, four artificial horizontal accelerograms, representing each one a seismic zone, are applied to the 2D models and the response in terms of collapse mechanisms and force displacements histories is deeply analyzed. A comparative discussion on the results obtained shows that the tower response may strongly depend on typological issues (presence of bell cells, big perforations, presence/absence of internal vaults, etc.) and geometric properties of the structures (e.g. slenderness, thickness of perimeter walls, etc.).
Seismic response of some ancient masonry towers in the Coastal Po Valley
MALLARDO, Vincenzo;ALESSANDRI, Claudio
2011
Abstract
Masonry towers constitute a huge amount of the Italian built heritage. For this reason, their safety assessment against earthquakes appears of very relevant societal importance. They are unique architectural typologies, usually conceived in ancient time exclusively to withstand vertical loads. On the other hand, the recent national and international norms encourage the use of sophisticated non-linear methods, to have a deep insight into the actual ultimate behavior of this kind of structures in the presence of strong horizontal excitations. In the present paper, belonging to a wider research project still in progress and aimed at the seismic analysis of several masonry towers in the Northern Italy, some existing masonry towers, differing from one another for the thickness of the perimeter walls, the height, percentage of perforations, are analyzed by means of a 2D non-linear dynamic code. The code is based on a relatively refined 2D discretization of the towers, obtained through rigid quadrilateral elements interconnected by non-linear axial and shear springs, exhibiting softening and energy dissipation under cyclic loads. Starting from a detailed survey of the structures and from the knowledge of the mechanical properties of the constituent materials, four artificial horizontal accelerograms, representing each one a seismic zone, are applied to the 2D models and the response in terms of collapse mechanisms and force displacements histories is deeply analyzed. A comparative discussion on the results obtained shows that the tower response may strongly depend on typological issues (presence of bell cells, big perforations, presence/absence of internal vaults, etc.) and geometric properties of the structures (e.g. slenderness, thickness of perimeter walls, etc.).I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
