Pantheon Dome Engineering: Triple Shell and Thrust Paths
A structural read of the Paris Pantheon dome—shells, rings, and how light and loads are choreographed.
The Pantheon’s dome is a layered negotiation between mass and light. Its triple-shell composition distributes loads while shaping a didactic oculus effect without a literal open oculus.
🧱 Shells and Rings
- Inner shell: visual surface; smoother curvature for light play.
- Intermediate shell: structural stiffener—controls deformation.
- Outer shell: weather defense; drains water away from joints.
🧮 Proportion and Thrust
Let the dome radius be (R) and the rise be (h). A conservative ratio keeps thrusts within pier capacity.
$$ ext{Rise Ratio} = rac{h}{R} in [0.5,,0.7] quad Rightarrow quad ext{stable lateral profiles} $$
🌀 Light Choreography
- Clerestory windows modulate vertical gradients.
- Painted coffers mimic depth; shadow lattices animate the interior.
- Floor mirror displays curvature for public pedagogy.
📊 Element Roles
| Element | Function | Effect |
|---|---|---|
| Inner shell | Visual surface | Controls interior optics |
| Middle shell | Structural stiffener | Lowers deformation |
| Outer shell | Weather skin | Protects joints |
The dome is quietly didactic—teaching visitors about form, light, and the discipline of thrust.
About the Author
Conservation Architect
As a Paris lover and travel writer, I created this guide to help visitors connect with the Panthéon’s stories — from faith and revolution to science and civic memory.
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