The pendentive

Assembled from 20 blocks · 2 evidence · 18 related

1. Story
2. A spherical triangle that carries a circular dome on a square bay. Four arches are thrown across the sides of the square; the curved triangles left between them rise from the corners and close into a horizontal circle at the top, on which the dome sits. The device is what lets a dome be placed over a rectangular hall rather than over a circular drum, and it is therefore the enabling invention behind the whole Byzantine and later Ottoman tradition of centrally domed halls. Pendentives concentrate the dome's entire load and outward thrust onto four points, which is structurally elegant and unforgiving: the four piers and their buttressing become the building. The alternative solution, the squinch - an arch or niche bridging the corner - appears in Sasanian and later Islamic building and produces a visibly different geometry.
3. Knowledge
4. The dome
5. The pendentive
6. Connections
7. The dome
8. Hagia Sophia, Constantinople / Istanbul
9. Justinian commissions Hagia Sophia from two geometers
10. Hagia Sophia is dedicated
11. The voussoir arch
12. The pendentive
13. The Pantheon, Rome
14. The Pantheon dome spans about 43 m in unreinforced concrete
15. Hagia Sophia is dedicated
16. The first dome of Hagia Sophia collapses
17. The steeper dome is dedicated
18. Evidence
19. Collected structural and historical studies of Hagia Sophia, covering the pendentive system, the 558 dome collapse and the steeper 562 rebuilding, and the building's subsequent structural history. V55 verification basis: real and standard, not consulted in this session.
20. Comparative structural analysis of large pre-industrial buildings, treating span, thrust and material strength as the variables that determine what each period could build. Supports the load-path framing used throughout this pack and the structural contrasts drawn between post-and-lintel, corbelling, the voussoir arch, the dome and the rib vault. V55 verification basis: this volume is a real and standard reference named in the Journey declaration, but it was NOT consulted in this session - WebFetch is refused by the environment egress proxy for all research domains and the session WebSearch budget was exhausted before production began.