The static model of San Gaetano church: New interpretive hypotheses

Abstract

One of the characteristics of the architecture of Guarino Guarini is the contrast between the real static system and the apparent one. The first consists of the structures that actually provide support for the building; the second one, instead, are the architectural elements that represent the formal transposition of constructive logic. The goal is to offer an image of a miraculous balance. In the two churches built in Turin, San Lorenzo and the Chapel of the Holy Shroud, Guarini uses hidden structures that support the elements above. These elements are crossed arches of bricks, wooden rafters, metallic chains, all hidden in the thickness of the external walls. Pendentives are hanging on the back with metal anchors, being simply stone coating. Starting from these data, the study analyses the church of San Gaetano in Vicenza, designed in 1675, through inedited three-dimensional models. The aim is to reconstruct the ideal static model, looking for the presence of hidden support structures here too. The plan is a double envelope, composed of nine domed spaces; the middle one is identified by four pillars. The central space is surmounted by a double-shell dome, not supported by pillars, but that seems to rest on the domes of the side spaces. The pillars and the overlying pendentives only support a balustrade diaphragm, which hides the impost of the dome from. It can therefore be assumed that Guarini would take a hidden structure, consisting of four brick arches, along the sides of the square surrounding the circle that identifies the dome, tangent to the inner faces of the pillars. These arches perpendicular to each other, with impost on the central pillars, bring the loads of the dome on the pillars themselves. The static role performed by ambulatory is to ensure, through his vaults, the thrusts opposed to those generated by the central dome. The very low thickness walls that surround the lateral spaces have no bearing function: the loads are concentrated at the intersections, identified by high thickness and free-standing columns.