Shells are curved structures that can transmit loads in multiple directions and are constructed using thin materials like concrete or reinforced concrete. They distribute loads across their surfaces through compressive, tensile and shear stresses. Large spherical domes are often constructed using inflated membranes as forms which provide support during construction. Domes over 300 feet require a grid structure to provide sufficient stiffness while minimizing weight. Shells and folded plates are constructed as uniform thin surfaces rather than stacked discrete pieces like frames. Domes, vaults, and barrel shells are examples of shell structures used in building construction.

1.  Shells can be defined as
curved structures capable
of transmitting loads in
more than two directions to
supports.
 Loads applied to shell
surfaces are carried to the
ground by the development
of compressive, tensile, and
shear stresses acting in the
in-plane direction of the
surface.

4.  Constructions of spherical domes
by using inflated membranes as
forms have proven to be a viable
solution to many problems.
 The largest shells constructed are
now less than 300 feet in diameter.
 For very large spans, a grid
constructed with pans is necessary
so that the dome will be stiff enough
and still weigh less than a uniform
depth.

5.  A vault may be defined as a single barrel shell,
supported on its side by walls or columns.

6.  Shells and folded plates are different than
stacked units and frames.
 The thin diaphragm forming the shell is
created uniformly rather than being
assembled in discrete pieces.
 Most shell and plate building enclosures are
constructed from reinforced concrete

7.  A shell arch has a
longitudinal cross
section of a barrel shell
or a folded plate, but is
a circular arch or other
shape in profile.
 There is less concrete in
the roof than in the floor
system, and the
reinforcing will be
minimum.

8.  Dome shells have emerged due
to a new concept in building
design.
 These structures have the
potential for significant markets
in commercial and many other
small residential and industrial
applications.
 The structures utilize superior
material technology

9.  Curved shell roofs can provide
large uninterrupted space in
many building types.

10. The arrangement consists of :
 external and internal layers of
glass reinforced cement (GRC)
 the strong stiff layers
 with a lightweight polyurethane
core forming the separation
medium required to develop the
sandwich action.

11. Construction of the domes involves a
three stage processes:
)a) Completed Slab, (b) Inflatable former, (c) Completed domeshell

12. As the diameter of the domes increases, the
stresses rise

13.  Barrel shells of
materials such as
wood, steel and
plastics are often
found.
 Reinforced concrete
is by far the most
common material

14. Edge beams serve
to:
 to stiffen the
shell edge
 to act together
with the shell in
carrying stresses

15.  The design for king
Abdullah Stadium
in Jeddah. The
shell design is
remarkable. The
building of this
giant stadium will
begin by the end of
this year.