2. ORIGIN
Commissioned by Emperor Hadrian
The word “Pantheon” loosely translates to
“all of the gods”… the Pantheon serves as a
temple to the Roman gods, the dome being
the divine feature
Built between 118-128 A.D.
1,887 years old (still in use today)
3.
4. DOME
Depth from dome’s apex to floor is exactly equal
to the width of the dome (142.4 ft)
Meaning: the rotunda (round floor beneath
dome) and dome are configured in accordance
with a perfect sphere
Because of no reinforcement to keep the dome
from trying to “push” or “flatten” out, Romans
built 20 ft thick walls to serve as buttresses for
the dome
Based on the “arch” concept
5.
6. WEIGHT OF DOME
The most critical issue Roman engineers
faced was the dome’s own dead weight
Roman engineers needed a material with a
larger strength to weight ratio than traditional
stone. Answer: concrete
Strength was not a central issue in the
design, but rather the weight and stresses
associated with the material used
7. ROMAN CONCRETE
Very strong by modern standards
For the Roman engineers, the concrete was
still too heavy, so they needed to develop
ways to reduce the amount used
Roman engineers conducted a stress
analysis of the dome and determined that the
compression stresses were smaller towards
the top. Solution: pour a progressively
thinner layer of concrete
8. ROMAN CONCRETE (CONTINUED)
Romans relied on the chemical reactions that
took place between the lime and pozzolans they
added into the mix to strengthen their concrete
Pozzolans – volcanic ash found in and around
Puzzuoli Bay near Naples (varies in dome)
Roman engineers used small hollow jars called
amphra as aggregate… used to displace
concrete to make mix lighter
9. ROMAN CONCRETE (CONTINUED)
Coffers – ingenious Roman innovation which
removed an array of concrete sections…
made the dome lighter and more appealing,
all while maintaining thick sections to serve
as reinforcement
Oculus – used to distribute the stresses
acting on the dome’s weakest point along a
rounded perimeter… also serves as an
aesthetic feature
10.
11. REFERENCES
Rome: Engineering an Empire
https://www.youtube.com/watch?v=C5obOUDy
Q5s
The Secrets of Ancient Roman Concrete
http://www.history.com/news/the-secrets-of-
ancient-roman-concrete
The Pantheon
http://www.romanconcrete.com/docs/chapt01/ch
apt01.htm
