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On the Structure of the Roman Pantheon
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0
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1986
Year
Roman PantheonReligious SymbolRoman ArchitectureLanguage StudiesMiddle RepublicClassics
The Pantheon is regarded as a pinnacle of Roman architecture, credited to advances in pozzolana concrete, stepped rings, and coffering that enabled its massive dome. The authors used numerical‑computer modeling of the dome to investigate theories of late Roman design rationale. The modeling showed that while stepped rings raise critical stresses in an uncracked dome, allowing cracks reveals a stress‑reducing effect, and the cracked dome behaves like an array of arches, implying that late Roman builders understood this and that architectural development was less driven by structural innovation than previously thought.
Since the time of its construction, the bold, brilliantly simple schema of Hadrian's Pantheon has inspired much emulation, commendation, and even fear. Modern commentators tend to view the building as a high point in an "architectural revolution" brought about mainly through the Roman development of a superior pozzolana concrete that lent itself to the forming of unitary, three-dimensional structures. Other factors cited for the technical success of the Pantheon include the use of a series of massive, concentric stepped rings and the lightening of the dome by coffering and gradated, light-weight aggregates. To investigate these theories, and thereby to understand late Roman design rationale better, a numerical-computer modeling study of the dome structure was undertaken. It yielded several surprises.Analysis revealed that the stepped rings induced higher, rather than lower, critical stresses in an uncracked dome model. But by allowing the model to crack freely, a salutary effect was caused by the rings. The cracked model closely simulated the behavior of the actual dome, which was discerned to act structurally as an array of arches. In fact, the configuration of the dome seems to indicate that the builders understood this which points to the conclusion that late Roman architectural development was not so closely tied to structural innovation as has been generally believed.