For Civil Engineers, Presenting you the Civil Engg. Facts about Shells and Roof Structures, It's also containing valuable informations about the Tensile Structures and Paraboloid Structures Thank you.

2. CONTENTS
• SHELL STRUCTURES
• DOME AND BARREL ARCH STRUCTURES
• CONE AND HYPERBOLOID STRUCTURES
• HYPER PARABOLOID STRUCTURES
• FOLDED PLATE STRUCTURES
• TENSION AND SKELETAL SPACE FRAME
STRUCTURES
• PNEUMATIC AND GRAINS STORAGE
STRUCTURES

3. SHELL STRUCTURES

4. SHELL STRUCTURES
 A Shell is a type of structural element which is
characterized by its geometry, being a three-dimensional
solid whose thickness is very small when
compared with other dimensions.
 In structural terms, by the stress resultants calculated in the
middle plane displaying components which are both
coplanar and normal to the surface. Essentially, a shell can
be derived from a plate by two means: by initially forming
the middle surface as a singly or doubly curved surface, and
by applying loads which are coplanar to a plate's plane
which generate significant stresses.

5. SHELL STRUCTURE IN OCEANOGRAPHIC VALENCIA

6. OTHER INFORMATION ABOUT SHELLS
 Structures,which keep their shape and support loads,even
without a frame, or solid mass material inside, are called
Shell structures.
 Shell structures use a thin, carefully shaped, outer layer of
material, to provide their strength and rigidity. The shape
of a shell structure spreads forces throughout the whole
structure, which means every part of the structure supports
only a small part of the load, giving it its strength.
 Examples are Igloos, Egg cartons, Turtle shell, Food or pop
cans or even bubbles in foam and cream puffs.

7. MISCELLANEOUS EXAMPLES OF SHELL STRUCTURES
EXAMPLES ARE IGLOO , EGG , HAZELNUT , HONEYCOMB

8. ACCORDING TO IS2204 :1962
TYPES OF SHELL

9. DOME AND BARREL ARCH
STRUCTURES

10. DOME STRUCTURES
 A dome is an element of architecture that resembles the
hollow upper half of a sphere.
 Dome structures made of various materials have a long
architectural lineage extending into prehistory.
 Dome is a rounded vault made of either curved segments
or a shell of revolution, meaning an arch rotated around its
central vertical axis.
 A masonry dome produces thrusts down and outward, So
Domes can be divided into two
kinds: Simple and Compound, depending on the use.

11. FACTS ABOUT DOME
 Domes are concave from below, they can reflect sound
and create echoes.
 The earliest domes in the Middle East were built with
mud-brick and, eventually, with baked brick and stone.
 Wooden domes were protected from the weather by
roofing such as copper or lead sheeting.
 Brick domes were the favoured choice for large-space
monumental coverings until the Industrial Age, due to
their convenience and dependability.
 The domes in the churches where semi-domes (apse), for
example, echoed the chants of the people.

12. EXAMPLES OF DOMES
TAJMAHAL in India is one of the best examples of Dome structures.

13. EXAMPLE OF DOME STRUCTURE
Dome of St. Peter's Basilica in Rome
crowned by a cupola. Designed primarily
by Michelangelo, the dome was not
completed until 1590
ROOFTOP OF BASUNDHARA CITY
MODERN DOME STRUCTURE

14. TYPES OF DOME
 Beehive dome
 Bulbous dome
 Cloister vault
 Crossed-arch dome
 Geodesic dome
 Hemispherical dome
 Onion dome
 Oval dome
 Parabolic dome
 Sail dome
 Saucer dome
 Umbrella dome
From clockwise: Large saucer dome, Umbrella dome
and Onion Dome

15. BARREL ARCH STRUCTURES

16. BARREL ROOF
 A barrel roof is a curved roof that, especially from below,
is curved like a cut-away barrel.
 They have some advantages over dome roofs, especially
being able to cover rectangular buildings , due to their
uniform cross-section.
 The barrel vault is the simplest form of a vault: effectively
a series of arches placed side by side, i.e., one after
another.
 It is a form of barrel roof.

17. BARREL ARCH VAULT
 A barrel vault, also known as a tunnel vault or a wagon
vault, is an architectural element formed by the extrusion
of a single curve along a given distance.
 The curves are typically circular in shape, lending a semi-cylindrical
appearance to the total design.
 Barrel vaults are known from Ancient Egypt, and were
used extensively in Roman architecture.
 This form of design is observed in cellars, crypts,
long hallways, cloisters and even great halls.

18. BARREL ARCH EXAMPLES
BARREL ARCH IN A OPEN CLOISTER

19. BARREL ARCH
 As with all arch-based constructions, there is an outward thrust
generated against the walls underneath a barrel vault. There are
several mechanisms for absorbing this thrust.
 An elegant method is to build two or more vaults parallel to
each other; the forces of their outward thrusts will thus negate
each other.
 This method was most often used in construction of churches,
where several vaulted naves ran parallel down the length of the
building.
 The third and most elegant mechanism to resist the lateral
thrust was to create an intersection of two barrel vaults at right
angles, thus forming a groin vault.

20. BARREL VAULT LATERAL DISTRIBUTIONS :
•Pointed barrel vault
showing direction of lateral
forces.
• The barrel vault structure
must rest on long walls
creating less stable lateral
stress, whereas the groin
vault design can direct
stresses almost purely
vertically on the apexes

21. CONE AND HYPERBOLOID
STRUCTURES

22. CONE STRUCTURES
•The conical structure as an example
has a diameter at eaves/gutter level of
8500 mm and a roof pitch of 40
degrees.
•The dimension from eaves to apex on
the sloping line of the roof can be
calculated by simple geometry.
•This dimension is important in the
setting out and template making
procedure.
•The circumference of the roof must
also be calculated to find the total
conical diameter (3.14 x D)
•Normally used as roof structures and
Channel and I sections are used
•Rarely used in Residential areas.

23. CONODIAL SHELLS

24. HYPERBOLOID STRUCTURES
 Hyperboloid structures are architectural
structures designed with hyperbolic geometry.
 Often these are tall structures such as towers where the
hyperboloid geometry's structural strength is used to
support an object high off the ground, but hyperboloid
geometry is also often used for decorative effect as well as
structural economy.
 The first hyperboloid structures were built by Russian
engineer Vladimir Shukhov (1853–1939).
 The world's first hyperboloid tower is located in Polibino,
Dankovsky District, Lipetsk Oblast, Russia.

25. HYPERBOLOID STRUCTURES
THIS HYPERBOLOID
STRUCTURE IS THE KOBE
TOWER IN JAPAN.

26. HYPERBOLOID STRUCTURES
AN EXAMPLE OF HYPERBOLOID
Cartesian coordinates for the hyperboloids can be defined, similar to spherical
coordinates, keeping the azimuth angle θ ∈ [0, 2π), but changing
inclination v into hyperbolic trigonometric functions:

27. SHUKHOV TOWER (1898) AN EXAMPLE OF HYPERBOLOID STRUCTURE

28. HYPER PARABOLOID STRUCTURE

29. HYPER PARABOLOID STRUCTURES
 The Hyperbolic Paraboloid form has been used for roofs
at various times since it is easily constructed from straight
sections of lumber, steel, or other conventional materials.
 The term is used because the form resembles the shape of
a saddle.

30. HYPER PARABOLOID STRUCTURES
 It is usually made up of a combination of four of
intersecting hyper Paraboloids joined together to form
a square shape in plan view.
 This form of structure is often used by architects to
roof large span exhibition halls and public buildings.
 The distribution of various components of forces is
obtained to give designers an in–sight of the behavior
of such complex structures

31. HYPER PARABOLOID STRUCTURES

32. HYPER PARABOLOID STRUCTURES
An example of
Paraboloid structure

33. FOLDED PLATE STRUCTURES

34. FOLDED PLATE STRUCTURES
 A thin walled building structure of the shell type.
 Folded plate structures consist of flat components, or plates,
that are interconnected at some dihedral angle.
 Structures composed of rectangular plates are said to be prismatic.
 In modern construction practice the most widely used
folded plate structures are made of cast-in-situ
or precast reinforced concrete (including prestressed and
reinforced-cement structures).
 The structures are used as roofs for industrial and public buildings.

35. FOLDED PLATE STRUCTURES
 The main advantage of folded plate structures over other shells
(such as cylindrical) is the simplicity of manufacture.
 More exact static calculations are based on limit
equilibrium and on P. L. Pasternak’s and V. Z. Vlasov’s general
theory of shells.

36. FOLDED PLATE STRUCTURES
Old Sears Store in Florida Present Sears Store in Florida

37. USES OF FOLDED PLATES

38. TENSION AND SKELETAL FRAME
STRUCTURES

39. TENSION STRUCTURE
 ATensile structure is a construction of elements carrying
only tension and no compression or bending.
 The term tensile should not be confused with tensegrity,
which is a structural form with both tension and
compression elements.
 Tensile structures are the most common type of thin-shell
structures.
 Most Tensile structures are supported by some form of
compression or bending elements, such as masts (as
in The O2, formerly the Millennium Dome), compression
rings or beams.

40. TENSION STRUCTURE THE O2 OR THE MILLENNIUM DOME

41. TENSION STRUCTURE
Types of structure with significant tension
members
Linear structures
 Suspension bridges
 Draped cables
 Cable-stayed beams or trusses
 Cable trusses
 Straight tensioned cables

42. EXAMPLE OF TENSION STRUCTURE : SUSPENSION BRIDGES
THE AKASHI BRIDGE SPANNING APPROX. 2 KILOMETERS IS A
EXAMPLE OF TENSION STRUCTURE.

43. ANOTHER TENSION STRUCTURE BY VLADMIR SHUKHOV
The world's first Tensile Steel
Shell by Vladimir Shukhov (during
construction), Nizhny Novgorod,
1895

44. TENSILE STRUCTURE
Three-dimensional structures
 Bicycle wheel (can be used as a roof in a horizontal
orientation)
 3D cable trusses
 Tensegrity structures
 Tensairity structures
Surface-stressed structures
 Prestressed membranes
 Pneumatically stressed membranes
 gridshell
 fabric structure

45. TENSILE STRUCTURE
MEMBRANE ROOF AND CABLE , BICYCLE , TENSGRITY

46. EXAMPLE OF PRESTRESSED CONCRETE TENSION STRUCTURE

47. SKELETAL SPACE FRAME
STRUCTURES

48. SKELETAL SPACE FRAME STRUCTURES
 In architecture and structural engineering, a Space
frame or space structure is a truss-like, lightweight rigid
structure constructed from interlocking struts in
a geometric pattern.
 Space frames can be used to span large areas with few
interior supports.
 Like the truss, a space frame is strong because of the
inherent rigidity of the triangle;
flexing loads (bending moments) are transmitted as
tension and compression loads along the length of each
strut.

49. SPACE FRAME SKELETAL STRUCTURES TYPES
Curvature classification
Space plane covers
 These spatial structures are composed of planar
substructures.
 Their behaviour is similar to that of a plate in which the
deflections in the plane are channelled through the
horizontal bars and the shear forces are supported by the
diagonals.
Barrel vaults
 This type of vault has a cross section of a simple arch.
 Usually this type of space frame does not need to use
tetrahedral modules or pyramids as a part of its backing.

50. SPACE FRAME SKELETAL STRUCTURES TYPES
Spherical domes and other compound curves
 Usually require the use of tetrahedral modules or pyramids and
additional support from a skin.
THIRUMALAI MRTS RAILWAY STATION BARREL SPACE
FRAME STRUCTURE

51. SPACE FRAME SKELETAL STRUCTURES CLASSIFICATIONS
Classification by the arrangement of its elements
Single layer grid
 All elements are located on the surface to be approximated.
Double layer grid
 The elements are organized in two parallel layers with each other at a
certain distance apart.
 Each of the layers form a lattice of triangles, squares or hexagons in
which the projection of the nodes in a layer may overlap or be
displaced relative to each other.
 The diagonal bars connecting the nodes of both layers in different
directions in space.
 In this type of meshes, the elements are associated into three groups:
upper cordon, cordon and cordon lower diagonal.
Triple layer grid
 Elements are placed in three parallel layers, linked by the diagonals.
They are almost always flat.

52. SPACE FRAME SKELETAL STRUCTURES CLASSIFICATIONS
L‘Agora SPACE FRAME
STRUCTURE , SPAIN

53. PNEUMATIC AND GRAINS
STORAGE STRUCTURES

54. PNUEMATIC STRUCTURES
 An air-supported or air-inflated structure which consists of
internal pressurized air i.e. structural fabric envelope.
 Air is the main support of the structure, and where access is via
airlocks.
 It is usually dome-shaped, since this shape creates the
greatest volume for the least amount of material.
 The materials used for air-supported structures are similar to
those used in tensile structures, namely synthetic fabrics such
as fibre glass and polyester.
 In order to prevent deterioration from moisture
and Ultraviolet radiation, these materials are coated with
polymers such as PVC and Teflon.

55. PNEUMATIC STRUCTURES
AIR SUPPORTED PNUEMATIC STRUCTURE

56. PNEUMATIC STRUCTURES
Advantages:
 Considerably lower initial cost than conventional buildings
 Lower operating costs due to simplicity of design.
 Easy and quick to set up, dismantle, and relocate .
 Unobstructed open interior space, since there is no need for
columns
 Able to cover almost any project
 Custom fabric colours and sizes, including translucent fabric,
allowing natural sunlight in.

57. PNEUMATIC STRUCTURES
Disadvantages:
 Continuous operation of fans to maintain pressure, often
requiring redundancy or emergency power supply.
 Dome collapses when pressure lost or fabric compromised
 Cannot reach the insulation values of hard-walled structures,
increasing heating/cooling costs
 Limited load-carrying capacity
 Conventional buildings have longer lifespan

58. GRAIN STORAGE STRUCTURES
A GRAIN STORAGE STRUCTURE IN WESTERN
AUSTRALIA FOR STORING CORN

59. GRAIN STORAGE STRUCTURE
 Grain storage structures are also known as the bins, or wheat
bins,
 Grain silos spread around the wheat belt ofWestern
Australia at grain importing locations
GRAIN SILOS COMES
UNDER THE
STORAGE
STRUCTURES .

60. OTHER RANDOM MISCELLANEOUS
STRUCTURES

61. A GEODESIC DOME DESIGNED BY BUCKMINSTER FULLER (A NEO
FUTURISTIC ARCHITECT)

62. ABOUT BUCKMINSTER FULLER
 Buckminster Fuller, an American Engineer,
invented the geodesic dome in the 1950’s
 Geodesic domes are made from separate
pieces of ‘material’ arranged in triangles,
pentagons and hexagons
 The position of the shapes and their sizes is
critical and needs Maths to work it out
 Geodesic Domes are the strongest lightweight
structures you can make

63. VLADMIR SHUKHOV TOWER (1922)

64. ABOUT VLADIMIR SHUKHOV
 Vladimir Grigoryevich Shukhov (1853 –1939)
was a Russian engineer
polymath, scientist and architect
 He is renowned for his pioneering works on
new methods of analysis for structural
engineering that led to breakthroughs in Civil
as well as Industrial designs.
 Hyperboloid structures, Diagrid shell structures
, tensile structures, Grid shell structures, Oil
reservoirs, pipelines, boilers, ships and barges
were his works.
 He is also the inventor of the first cracking
method.