I chose to report on the pantheon because Iíve seen pictures and I am
also very fascinated by all the Roman monuments. I looked all around the
internet and libraries. The Pantheon was very hard to find information about. It
was very challenging but I found enough information to complete this report.

This famous building stands in the business district of Romemuch as it was built
some 18 centuries ago. Amazingly, it has withstood the ravages of both the
elements and war permitting a firsthand view of a unique product constructed by

Roman hands. Now, it is exposed to acid rain and fumes from passing automobiles
and overshadowed by buildings of inferior taste; but, with trust in the future,
the Pantheon will survive. Unrecognized, the design of this ancient concrete
building reveals unparalleled features not encountered in modern design
standards. Recent studies reveal several major cracks in the dome, but it still
functions unimpaired. This condition will surely excite the curiosity of our
structural engineers. The building was built entirely without steel reinforcing
rods to resist tensile cracking, so necessary in concrete members, and for this
concrete dome with a long span to last centuries is incredible. Today, no
engineer would dare build this structure without steel rods! Modern codes of
engineering practice would not permit such mischief. No investor with knowledge
of concrete design would provide the funding. Additional constraints when
attempting to build a structure as large as the Pantheon will be discussed
later, but briefly they include the use of inadequate hand tools and unsafe
lifting devices. I believe we can learn from this activity. Workers can build
from a plan and can successfully use their proven practices only if construction
quality controls are maintained. History tells us that the Pantheon is a Greek
word meaning to honor all Gods (particularly the Olympian divinities). It is
ironic that our building has existed throughout many wars while being dedicated
to all Gods; one can readily perceive this to be a temple for our one God. And,
the Church has claimed this holy structure as a resting place for its most
famous Popes, so we continue to honor its magnificent divinity. The first
incarnation of this ancient temple was built by Agrippa, the son-in-law of the

Roman Emperor Augustus, about 27 B.C. Today, above the entrance carved in stone
are the words "M. AGRIPPA L. F. COS. TERTIUM FECIT" which is
translated, "Marcus Agrippa, son of Lucius, in his third consulate, made
it." Indeed, it is worth mentioning that Agrippa's engineering talents were
used in building the famous Pont de Gard aqueduct in France. As with many
cities, tragedy in the form of large fires such as those of 60, 64, 79, 100 and

110 A.D. seemed to strike Rome. Originally, many Roman buildings contained
travertine (limestone rock) which easily cracked in fires. The first Pantheon
was severely damaged and required replacement except for some parts of the lower
porch section and foundation. The Pantheon was rebuilt by the Emperor Hadrian
during the period 118 to 128 A.D. (a time given by Ward-Perkins).2 But the

Ward-Perkins's period is disputed by, Lugli who said the building was started
sometime after 123 A.D. and was finished by Emperor Pius about 140 A.D.3

However, most of the bricks were made and placed in the Pantheon in 123 A.D., a
date that the maker stamped on his bricks. This was discovered in 1892 by the

French archaeologist, George Chedanne. It appears the construction of the
rotunda walls took a period of 4 to 5 years, and the dome required a like period
because of its height and the meager tools the Romans used. This long
construction period was fortunate as it gave this pozzolan concrete ample time
to cure and gain strength. Was the second temple like the first? Yes, the
fundamental principle of the old Roman religion required that the temples be
rebuilt without changes in original form. Tradition required that the main
entrance face north, and thus the whole building was oriented on the north-south
axis of the building. A description of its structural features is separated into
the configuration, foundation ring, circular walls, and dome to more clearly
define various components. How these pieces are unique in view of today's design
requirements will be discussed shortly. Body The Pantheon is one of the great
spiritual buildings of the world. It was built as a Roman temple and later
consecrated as a Catholic Church. Its monumental porch originally faced a
rectangular colonnaded temple courtyard and now enfronts the smaller Piazza
della Rotonda. Through great bronze doors, one enters one great circular room.

The interior volume is a cylinder above which rises the hemispherical dome.

Opposite the door is a recessed semicircular apse, and on each side re three
additional recesses, alternately rectangular and semicircular, separated from
the space under the dome by paired monolithic columns. The only natural light
enters through an unglazed oculus at the center of the dome and through the
bronze doors to the portico. As the sun moves, striking patterns of light
illuminate the walls and floors of porphyry, granite and yellow marbles. Inside
the Pantheon The building design is one of a large round shape very much like a
large barrel with a dome covering the top. There is a light-well in the center
of the dome. Layers of beautiful thin brickwork cover the outside, round walls.

Small access holes appear occasionally in the wall which were used during
construction to frame interior voids. The main entrance is thoroughly
impressive: double bronze doors 21 feet high (6.4 meters), a lasting and fitting
contribution from their metal smiths. These doors are protected by a high, broad
porch, made with 16 well arranged granite columns supporting a gable styled
roof. The beams in the roof structure of the porch are wooden. They were
substituted for bronze members stripped-out by those in later years needing
metal for their canons. Professional Roman surveyors located the inlaid marble
floor to conform with a convex contour which drained away the rain from the
oculus for these hundreds of years. In the following descriptions, some general
dimensions are given to indicate the magnitude of this undertaking by the

Romans. The rotunda has a rather awesome inner diameter of 142.4 feet (43.4 m),
made mostly of concrete. Comparatively speaking, this distance represents about
one half the length of our football field. And from the floor to the top of the
opening in the dome is the same distance. As a matter of fact, we could think of
the design of this building as one that could contain a theoretical ball some

143 feet in diameter. The design is not entirely unusual because there are other

Roman buildings which have a similar configuration, but the size is unusual.

Other buildings such as the Temple of Mercury (71 feet/21.5 m diameter) at Baiae
and Domitian Nympheaum at Albano (51 feet/15.6 m diameter) have domes of this
type. The Pantheon still has the longest span constructed before the 19th

Century. To provide details on this complex configuration, the following figures
show the building with its two-ring foundation, voids in the walls, and the
step-ring and coffer arrangement in the dome. Foundation The Pantheon was built
on marshy, unstable earth which gave a serious supporting problem to its
builders. The Jutland Archaeological Society described in detail various aspects
of the ring foundation; they found it rested on a bed of bluish colored river
clay.8 This condition invited disaster, and in the final construction phase, the
foundation cracked at the two ends of the North-South axis. If one section of a
building settles slightly faster and lower than an adjacent section, very large
bending stresses are initiated at a point between these two sections which can
crack the concrete. And uneven settling was the problem given to the builders.

The present-day engineering solution to this type of foundation problem is to
drive piles through the clay to bedrock so the building will be firmly supported
all the way around. The Roman builders chose a different approach. They built a
second ring to hold the first ring from cracking further and to give the clay
more area to support the structure. It worked because the building has lasted
over 1800 years. In addition to keeping the crack from extending, the builders
placed buttress walls on the south side opposite the massive porch. This acted
as a clampng device; and although the structural projection appears to be an
additional room, it only serves the purpose of being part of the clamp. These
rings are made of pozzolan concrete consisting of travertine pieces in layers
held together by a mortar of lime and pozzolan. This will be discussed later in
this work. Interestingly enough, the Jutland Society's investigation showed the
foundation material had become "rock hard,"11 a case we might expect
when we study the chemistry of pozzolanic reaction under these conditions. How

It Stands up The challenge of determining stresses within various sections of
the Pantheon has always excited both architects and engineers who are interested
in the building. Technical design people recognized that the long 143 foot span
of the ancient dome could have critical stress concentrations leading to a
catastrophic failure of the structure, but this has not happened. Nothing in
life seems perfect, and this is the case with the Pantheon. The dome and walls
have cracked. Concrete cracks under excessive tensile stress as viewed in a hoop
condition. A. Terenzio, an Italian superintendent of monuments, documented
cracking in the walls and dome duringhis inspection of the Pantheon in 1930.

Terenzio identifies fractures `reaching from the base of the rotunda to the
summit of the dome' that he thought were brought about by differential
settlement from uneven loading of the wall, particularly near the entrance of
the rotunda in the principal niche. Rather than finding vertical differential
settlement, we have observed only traces of lateral opening across the cracks
corresponding to the effect of hoop tension. Terenzio believed cracking occurred
shortly after construction because of dated brick repairs. The Mark and

Hutchinson study showed that meridional cracking in the dome was in the lower
half extending up to about 57 degrees from the horizontal on the spring line. An
earlier stress analysis of this dome by Cowan theoretically placed this point at

37 degrees 36'. This is the point where hoop stresses in the dome change from
tension to compression presenting a point of weakness within the unreinforced
concrete dome. This theoretical point is in reasonable agreement with the actual
end of meridional cracking. The Mark and Hutchinson study located the cracks as
occurring generally at the openings within the upper cylindrical wall which
increased local tensile hoop stresses. In addition to dome, Terenzio mentioned
that cracks in the walls extended upward from 24.6 feet (7.5 m) above the floor.

The cracking pattern of the concrete in the Pantheon provides an unique stress
configuration acting in the dome and walls. Mark and Hutchinson describe this
picture as one in which the major internal forces in the cracked dome are only
in the meridional direction, and this region serves as a series of arches which
bears a common compression keystone in the form of the uncracked upper dome. The
cracked walls serve as a series of independent piers to support these arches.

Perhaps as insurance against som future dislocation, should we add a steel band
around a step-ring? Although the building has survived centuries, this valuable,
cracked landmark of Roman history should be protected against future earthquakes
at a small cost. Conclusion As you can tell the Pantheon was a great structure
created by the Romans. I believe it has played a great role in Greek history.

Even though this building is unpopular to many people, but this report proves
that it is one of the greatest and most historical man made creation.



95 Encyclopedia H. W. Cowan, The Master Builders. John Wiley and Son, New York,

1977 Http://www.broyan/sor/ Programmer: Jack M. Loudel