Pantheon Dome Engineering: Triple Shell and Thrust Paths

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

The dome is quietly didactic—teaching visitors about form, light, and the discipline of thrust.