Temporary structures as part of the constructive process: a centering system proposal for the oval dome of San Carlo alle Quattro Fontane

Abstract

During the constructive process of some domes, it will be necessar the utilization of temporary structures to withstand the materials and guarantee their stability. Furthermore, in the case of oval domes, some of these structures, such as centering systems, become essential, which not only will have a structural function but will also guide the geometry of the construction and define the outline to be followed by the laying of the rows of bricks. When considering the volumetric conformation of these domes, the inherent geometry of the centering structure could be therefore considered the unequivocal link between the graphic design and the real construction. In the specific case study of the oval dome of San Carlo alle Quattro Fontane, whose architect, Francesco Borromini, was aware of some stability principles, the thickness of the masonry, as well as the opposition of forces along the directions in which them are distributed, were also used to add stability to the whole. Thus, this knowledge of load distribution and static configuration would have been essential to design, place and size the different elements of the centering system probably used for the construction of the dome. Based on these geometric and structural considerations, a surveyed digital copy of the real construction has been analyzed to propose a feasible centering system used during the construction of this dome.