New historical records about the construction of the Arch of Ctesiphon and their impact on the history of structural engineering

A piece of historical research about the construction of the ancient Arch of Taq-iKisra, part of the imperial palace of the Sasanian Empire in the city of Ctesiphon, has been carried out. The information obtained, an analysis using graphic statics, the use of a physical model with hanging chains, and an ad hoc optimization program written in MATLAB have shown that the designer of this sixth century ad arch, a Byzantine named Farghán, was aware of the effects of the uneven distribution of loads and the differential settlements of the foundations on the equilibrium shape of structures working exclusively in compression and was able to control them. This discovery predates the earliest statement about the link between the shape of the catenary and that of an arch, by Robert Hooke, by eleven centuries and makes this building relevant not only because of its historical, archaeological, and architectural importance, but also because of its importance in the history of structural engineering. The building is currently in need of restoration to stop its collapse, and an awareness of the way it was designed could be of practical use for the definition of the intervention needed.