video 2019 click here: velumnimes velum colosseum

The following pages are the work of two French engineers graduated from the Arts et Métiers school of Aix en Provence 50 years apart :


René Chambon born in 1934. It was from 2004, at age 70, that he undertook to unravel the mystery of the roofs of Roman amphitheatres, using his reminiscences of the laws of the forces and the RDM (Resistance of the materials) ... and his spare time availability.


Vivien Poujade born in 1984, creator of his computer graphics company "3D Synthesis" at age 20 while still at school. In 2014 the said company has 3 agencies and employs …….
See his website www.synthes3d.com.




« How could one draw the velum on ? » was astonished Emile Zola at the foot of the ruins of the Colosseum, as shown by the two photographs below, during a visit to Rome, a little before 1900. By velum he heard an immense sky of shady fabric which, he As early as the first century AD, it did not ignore the 50,000-seat grandstand of the famous monument.

Some figures on the following page briefly recall the fantastic realizations, of stone and wood, of the Romans. Rome was the largest city of antiquity, populated by one million inhabitants in the fourth century AD. Older civilizations, egyptian, minene, persian, greek ... had already built gigantic buildings but it comes back...


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It was chosen to calculate the elliptical velum of an ancient amphitheater by extrapolating the calculations applied to a virtual circular amphitheater having a radius of the same value as the largest radius of curvature of said amphitheater and with a number of masts providing a distance from one to the other very close to that measured on the backed up supports (3m in Nîmes, 2m in the Colisée). It is in fact at the right of this greater radius of curvature that the centripetal tensions of the arms and halyards generate the most important tangential reactions on the central ring.

The method consists of first determining the forces at the ends of an assembly line of two elementary rectangles of fabric and then transferring them in the opposite direction to the other organs....


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