HyparGate: Italian researchers reviving the ancient art of stereotomy

Italian architects of the New Fundamentals Research Group (Polytechnic University of Bari) and engineers from Roma Tre University are designing and constructing innovative reinforced stone shells and reviving stereotomy, the ancient art of cutting stones.

Using advanced modeling and analysis software, and robotic fabrication, the team, coordinated by Prof. Giuseppe Fallacara, has designed the HyparGate, the first discrete hyperbolic paraboloid made of stone. The HyparGate covers a free area of 22 square meters thanks to the cantilever morphology of the shell. The hypar is a well-known ruled surface that has been used in the last decades for many structural applications related to reinforced concrete shells. The full-scale construction is located in France, representing the entrance portal to the headquarters of the French company S.N.B.R.. The main idea is to replace reinforced concrete with pre-stressed stone in order to reduce the use of artificial materials in architecture as much as possible.


Focusing on the hypar’s morphological properties, an aspect of considerable importance in terms of structural analysis and fabrication is that it can be easily described in an analytic way as a parametric surface. The mathematical description allows the direct calculation of some geometric quantities that characterize the structural behaviour. Furthermore, it is one of the most famous ruled surfaces: it may be generated using two families of line segments called “generatrices.” This feature is particularly important in this case because it implies a simple way of dividing the stone into modules, and above all, it permits the use of post-tensioning with rectilinear steel bars in order to eliminate residual tensions along the generatrices.


The main intent is to establish an innovative connection between shape, structure, and fabrication, and to generate a series of new self-supported vaulted morphologies through integrated parametric analyses. This computational approach underlines the potential of robotic fabrication in architectural fields, making possible the fabrication of optimized voussoirs modelled using parametric software. The fabrication process includes the use of robotic arms in combination with CNC manufacturing techniques like circular saw cutting, milling, and diamond wire cutting. The whole research aims to demonstrate that by seamlessly combining digital fabrication tools, architectural design, and mechanical analysis, it is possible to develop innovative structural morphologies with intrinsically high aesthetic value and a high degree of sustainability.



Title: HyparGate

Concept & design: Prof. Dr. Giuseppe Fallacara

3D drafting and optimization: Giuseppe Fallacara, Nicola Martielli, Maurizio Barberio, Bertrand Laucournet

Structural analysis (prestressed reinforced stone): Prof. Ing. Nicola Rizzi, Valerio Varano, Daniele Malomo

Fabrication and construction: S.N.B.R. Société Nouvelle Le Batiment Régional

Location: SNBR Bureaux – 2 Rue Alcide de Gasperi, 10300 Sainte-Savine, Troyes (France)

Chronology (design, fabrication and construction): 2014 – 2016

Stone type: Armenian travertine

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