The voussoir arch

Assembled from 25 blocks · 2 evidence · 31 related

1. Story
2. A curved span built from wedge-shaped blocks (voussoirs) set on a temporary timber former called centring and locked by the last stone, the keystone. Because each voussoir is wedged against its neighbours, the whole ring is in compression and the load runs down through the curve to the ground - which is exactly what stone, brick and unreinforced concrete are good at. The price is horizontal thrust at the springing, which must be resisted by a heavy pier, an abutment, buried fill, or by the next arch in an arcade pushing back. The arch was known in Mesopotamia and Egypt well before Rome, but Roman builders industrialised it: standard voussoir geometry, reusable centring, arcades that cancel each other's thrust, and the extension of the same logic into barrel vaults, groin vaults and domes. Once the arch exists, span stops being set by the tensile strength of a beam and starts being set by how much thrust you can absorb.
3. Knowledge
4. Corbelling (the false arch and false dome)
5. The voussoir arch
6. Connections
7. Colosseum (Flavian Amphitheatre), Rome
8. Pont du Gard
9. Load path
10. Corbelling (the false arch and false dome)
11. Corbelling (the false arch and false dome)
12. The dome
13. The Gothic rib vault
14. Roman builders adopt pozzolanic concrete
15. The Pont du Gard carries an aqueduct on three tiers of arches
16. The Colosseum opens: arch and concrete at civic scale
17. Great Pyramid of Giza (Pyramid of Khufu)
18. The voussoir arch
19. The voussoir arch
20. Treasury of Atreus, Mycenae
21. The Great Pyramid is built as mass, not span
22. The corbelled tholos at Mycenae sets a record that stands for fourteen centuries
23. Evidence
24. 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.
25. Standard study of Roman concrete vaulting, its materials, aggregate selection and construction sequence, including the graded-aggregate practice used in large domes. Supports the MATERIAL_ROMAN_CONCRETE and SITE_PANTHEON records. V55 verification basis: real and standard, but not consulted in this session; no research domain was reachable.