B.TECH STUDENT SASTRA UNIVERSITY

1. MONOLITHIC
DOME
S.PADMASHRE
IIIrd YEAR
C SECTION

2. INTRODUCTION
Monolithic Dome is thin wall reinforced
concrete shell structure.
The structure provides safe shelter for the
people area with hurricanes,fires,bomb
blasts and earthquakes.
Building consist of : an outer airtight
form,polyuretane foam, reinforced concrete.
2

3. This technique is an effective
alternative to conventional methods.
A curve rotated about a central axis to
form a surface, creates a DOME.
A Monolithic dome is a structure cast in
a one piece form.
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5. MONOLITHIC DOME
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6. HISTORY
The igloo may be the earliest form of
monolithic dome. While it is constructed
of blocks of compressed snow, these
blocks melts and re-freeze to form a
strong, homogeneous structure.
The strength is due to the natural
strength of the arch and insulation is
due to the minimal surface area of the
spherical section.
6

7. Turtle Reams was built by first creating
mould of dirt in the desired shape of
the shell, an ellipsoidal section 73m
long,49m wide and 12m high.
The mould was then covered in a grid of
rebar, to provide strength and a layer
of concrete 100mm thick.
7

8. After the concrete was cured, the dirt
was excavated through the doorways,
leaving the roof standing in its place.
The floor was then poured to finish the
structure.
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9. MATERIALS USED
FOOTING :
A monolithic dome starts as a concrete
ring foundation, reinforced with steel
rebars.
For smaller domes, an integrated floor
and ring foundation may be used.
Vertical steel bars embedded in the ring
beam foundation are later attached to the
steel reinforcing of the dome itself.
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10. AIRFORM KITS :
The kit consisted of a 1220cm(40ft)
diameter form along with reinforced
steel anchors.
It is ordered in the shape of half
sphere with no custom windows or door
augmentations.
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11. POLYURETHANE FOAM :
Sprayed on polyurethane foam
insulation was of type using a part
process in which Diaphenylmethane-
4,4-diisocynate was mixed with blended
polyolresin.
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12. REINFORCING STEEL :
Steel in the foundation and slab was
16mm and grade 40 rebar.
Dome shell 13mm and 9.5mm grade 60
rebar was used.
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13. CONCRETE :
Foundation and slab a standard sack
concrete foundation mix was used.
Concrete used in the dome shell was 9
sack per cubic yard mix. This was made
up of 385kg Portland Cemnt,992kg
sand,178kg(1cm) gravel,0.7kg plastic
fibres and 118ml of air entraining agent
in additional to that of water.
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14. EXTERIOR :
Exterior coatings are an essential
aspect in the longevity to the Dome
Exterior.
Coatings serve as a UV shield to protect
the Airform and foam insulation as well
as achieve a desired appearance.
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15. CONSTRUCTION OF DOME
Monolithic dome is a rounded building
structure typically made of concrete
and rigid steel rods.
It consist of an outer airtight form,
polyurethane foam insulation and
reinforced concrete.
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16. The building process of monolithic domes
entailed :
Lay down the foundation of the dome ,
usually made of reinforced concrete.
An air form or fabric is inflated over the
foundation .
Polyurethane foam is then added to the
inside of the form in two layers of
(7.6cm)thick. 16

17. Special clips are affixed to the foam
interior, and rebar is installed.
Finally concrete is poured over the air
form, rebar, and foam supporters and
dome like shape emerges.
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18. 18

19. STEPS OF
CONSTRUCTION
STEP ONE : Ring Beam Foundation
Monolithic Dome starts as a concrete
ring foundation.
Continuous reinforcing bars are
embedded in the ring beam foundation.
The ring creates a solid base to
construct the dome.
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20. Concrete ring foundation
20

21. STEP TWO : Inflate Air form
Made of tough, weather -impermeable
material.
The air form is inflated with dual
inflator fans.
It determines the final shape of the
dome.
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22. STEP THREE : Polyurethane foam
Foam is applied in the interior to stiffen
the air form, and provide a secure surface to
which reinforcement bar is affixed.
It get hardens and creates a superior
insulation layer.
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23. STEP FOUR : Steel Reinforcing
Steel reinforcing rebar is attached to
the foam using a specially engineered
layout of hoop and vertical steel bar.
Small domes need small diameter bars
with wide spacing.
Large domes require
larger bars with closer
spacing
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24. STEP FIVE : Shotcrete
It is a special spray mix of concrete, applied
to the interior surface of the dome.
The steel rebar is embedded in the concrete
and when about 7cm
of shotcrete is
applied.
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25. Concrete was applied by shotcrete
process over a period of four days. Each
day from(1.25cm to 3.8cm)of concrete
is applied.
Blowers were left on for 8 hours and
then shut off.
The airlock was then closed for 30days
to allow curing on the concrete.
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26. To provide a smooth finished surface, a
layer of cement based plaster was alter
hand applied and finished.
This was primed with water based
acrylic latex and finished with acrylic
latex enamel.
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27. PROFILE AND SHAPES
The profile of a dome determines the
size of its surface area or dome shell,
and the amount of surface area affects
the construction cost.
The surface area of hemisphere dome
is twice that of its floor area i.e.,
2*pi*radius*radius.
Most of the monolithic dome have an
oblate ellipse profile.
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28. SHAPES
DOME
VARIATIONS/CONFIGURATIONS
a) Low profile spherical segment :
Most efficient shape.
Used for large domes.
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29. b) Hemisphere :
Surface area is double the floor area.
Useful for high-volume storage buildings
and smaller structures ,such as homes.
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30. c) High profile spherical segment :
Most volume for the least floor area.
Used for e water tanks, storage
buildings, homes etc.
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31. d) Oblate ellipsoid :
Very efficient for single structures.
Wall have maximum vertical slope vs.
structure size
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32. e) Prolate ellipsoid (Long axis
horizontal):
Elliptical base creates a very unique
space
f) Prolate ellipsoid (Long axis vertical)
:
It is very tall.
Useful for bulk storage and buried
building.
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33. Horizontal
Vertical
Prolate ellipsoid 33

34. g) Torus :
Not as space -efficient as dome.
These are homes with a centre
courtyard or garden.
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35. DOME PROFILES
Lower the profile the less expense.
Windows and doors on the second floor
can be augmented.
If the land is a premium, go up with
integrated stem wall.
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36. Caterpillar combination Dome
profiles
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37. MULTI-DOME
COMBINATION
The caterpillar is great design .
60 feet wide , 300-500 feet long.
Easy to build and allow for linear
functions.
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38. DOME OPENINGS
If dome is not huge, then all kinds of
openings are possible.
Stresses are higher in domes having
diameter larger than 100 feet.
Build the openings for the uses.
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39. STRESSES ACTING ON
DOMES
Generally, a spherical dome may be
imagining consisting of a number of
horizontal rings placed one over the
other.
The diameters of the successive rings
increase in the downward direction and
the equilibrium is maintained
independently of the rings above it.
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40. The circle of each ring is called latitude
while the circle drawn through two
diametrically opposite points on a
horizontal diameter and the crown is
known as a meridian circle.
The entire meridian circles coverage at
the crown of the spherical dome.
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41. Two types of stresses acting on the
domes are :
Meridian thrust (T) along the direction
of meridian
Hoop stress along latitudes
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42. ADVANTAGES
Advantages of a monolithic dome fall into
three general categories :
a)Economy in construction :
Cost of a dome is less .
Streamlined construction process and
use of only four ingredients contribute
to the domes economy.
Require less maintenance.
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43. b)Security :
Ability to survive tornadoes, hurricanes
and earthquakes.
Provides fire protection.
They are very good for circulation of air
and heat so they are also for very cold
climates.
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44. c)Aesthetics and comfort :
Any structure appears bare and
unattractive when its first built and
unenhanced. But just as enhancement
can soften and beautify straight lines
and corners.
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45. d)Rapid construction :
Most are prefabricated.
The prefab elements are relatively small
and light weight.
This makes easy to transport them to
the site.
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46. DISADVANTAGES
Disadvantages of monolithic dome :
a)Engineering :
Only specially trained construction
crews. Using the modern techniques.
Wasted space in narrow corners.
Lack of seams.
46

47. b)Social :
Different appearance of the domes
decreases the appeal for their use as
private residences and the strange
appearance and design may run afoul of
neighbourhood building covenants.
Depending on the situation a large
variety of variations available from the
standard circular shape can avoid some
of these problems. 47

48. Building permits may be difficult to
obtain if local officials are not familiar
with the monolithic dome.
Resale of a monolithic dome home may
be difficult because of its
unconventional appearance.
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49. CONCLUSION
Monolithic Dome building technique is an
effective alternative to conventional
methods.
Monolithic domes are disaster
-resistant, energy efficient and cost
effective.
Safest buildings that can be built and
can be designed for many uses.
Monolithic domes are designated as
tornado shelters. 49

50. REFERENCES
https://en.wikipedia.org/wiki/Monolithic
_dome
www.monolithic.org/round2it/technical-
journal-think-round
South D.B et.al 1990, “Economics and
the thin shell dome” , Concrete
International Reprint.
Nanette South M.S, engr. Str. & Mech ,
et.al “Finite Element Modelling of
Monolithic Dome structures”. 50

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