Abstract:
The study aims to analyse the two static models most widely adopted by Bernardo
Antonio Vittone, through the comparison of two churches in Turin: Santa Chiara and San
Leonardo. They are double envelope buildings, with central dome, respectively 10 and 15
meters in diameter, supported by eight pillars and surrounded by a continuous ambulatory.
The static model of Santa Chiara provides the internal pillars that play the main structural role
and cooperative outer envelope: the dome transmits his loads directly to the interior pillars.
The walls and vaults of the lateral chapels have an important role, arranging themselves
around the main dome, like a ring of containment of the horizontal thrusts induced by the
dome itself. Also the choirs, that Vittone places in smaller spaces behind the pillars, play an
important static role: their horizontal structures connect the pillars with the rear wall, which
thus offers its collaboration to contain the horizontal thrusts.
The church of San Leonardo has a reverse operation, with the dome that rests on the
outer walls, while the internal pillars support only a raised gallery.
Through three-dimensional info graphics models, the study shows that the entire
structure is designed as a discretized system, which replaces the traditional structure based
on continuous wall and uniformly distributed loads. The brick vaults are ribbed structure, in
which arches and ribs convey loads on the pillars or in precise high-resistance points of the
external masonry. This feature makes the space open to the light; also reduces the masonry
mass, saving material and reducing construction costs.
The formal representation of structural components agrees with the effective static
operation of buildings: the decoration on the surface of the dome indicates the presence of
ribs. The groins are hollow and open in order to highlight the condition of non-load bearing
element.
