ARC423 Advanced Building Systems

Lecture Notes for Wednesday, February 12, 2003

• The Duomo has a double shell construction.
• Interior shell is structural. It is not uniform in its thickness. It is about 12 feet thick at the bottom and five feet thick at the top.
• Exterior shell is aesthetic and acts as watershed. It is about two feet thick at the bottom and some one foot thick at the top.
• Tension rings (stone chains) were built into the interior dome at 4 points. They are made of sandstone.
• It is contested whether the rings provide tensile resistance.
• One wooden chain is also embedded within the dome to resist tensile forces.
• Stone chain similar to a set of railroad tracks.
• 8 ribs are 20’ thick and run from the collar to the oculus ring.
• 16 minor ribs, made of brick
• Horizontal ribs tie vertical ribs together. They very in their depth being thicker towards the main ribs and taper to the minor ribs. While they may provide some for lateral support the primary reason may be that the exterior shell is too thin to enclose a circular form, as the interior shell does. Thus the horizontal ribs act as circular forms which stiffen the exterior shell Possibly inspired by the coffering of the pantheon’s dome. Ribs made of brick.
• Spina-pesce (literally spine fish, loosely herringbone), refers to the type of brick coursing used to make the ribs.

Next