Arch

cypriotcamelUrban and Civil

Nov 29, 2013 (3 years and 8 months ago)

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Do you know
what arches
are?

An arch

is a curved structure capable
of spanning (separate, opening) a
space while supporting significant
weigh upon it. This structure
appeared in Mesopotamia, Egypt and
other ancient cultures, but it was
refined by Romans.

More About Arches:


History


Construction


Technical aspects


Types of arches


Arches built with different materials


Examples

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History

Arches were used by
the Persian, Harappan,
Egyptian, Babylonian,
Greek and Assyrian
civilizations for
underground structures
such as drains and
vaults, but the ancient
Romans were the first
to use them widely
above ground although
it is thought that
Romans learned it from
the Etruscans. The arch
has been used in some
bridges in China since
the Sui dynasty and in
tombs since the Han
Dynasty.

Arch of the General Staff Building
in Palace Square, St Petersburg

The so
-
called Roman arch is
semicircular, and built from an
odd number of arch bricks
(called
voussoirs
). You need an
odd number of bricks for there
to be a
capstone

or
keystone
.
This the topmost stone in the
arch. The Roman Arch's shape
is the simplest to build, but not
the strongest. There is a
tendency for the sides to bulge
outwards, which must be
counteracted by an added
weight of masonry to push them
inwards. The semicircular arch
can be flattened to make an
elliptical arch. The Romans
used this type of semicircular
arch freely in many of their
secular structures such as
aqueducts, palaces and
amphitheaters.

Roman aqueduct
supplying Carthage,
Tunisia.

The semicircular arch was followed in
Europe by the pointed Gothic arch or
ogive, whose centreline more closely
followed the forces of compression and
which was therefore stronger. This
design had been used by the Assyrians
as early as 722 BC. The parabolic and
catenary arches are now known to be
the theoretically strongest forms. A
parabolic arch was introduced in the
Ponte Santa Trinita, Florence,
constructed by the architect
Bartolomeo Ammanati from 1567 to
1569. Parabolic arches were introduced
in construction by the Spanish
architect Antoni Gaudí, who admired
the structural system of Gothic style,
but for the buttresses, that were
designated by him “architectural
crutches”. The catenary and parabolic
arches carry all horizontal thrust to the
foundation and so do not need
additional elements.

The horseshoe arch is based on the semicircular arch, but
its lower ends are extended further round the circle until
they start to converge. The first examples known are
carved into rock in India in the first century AD, while the
first known built horseshoe arches are known from Aksum
(modern day Ethiopia and Eritrea) from around the 3rd

4th
century, around the same time as the earliest
contemporary examples in Syria, suggesting either an
Aksumite or Syrian origin for the type of arch. It was used
in Spanish Visigothic architecture, Islamic architecture and
mudéjar architecture, as in the Great Mosque of Damascus
and in later Moorish buildings. It was used for decoration
rather than for strength.

Gateshead Millennium bridge
Arch

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Construction

An arch requires all of its elements to hold it together,
raising the question of how an arch is constructed. One
answer is to build a frame (historically, of wood) which
exactly follows the form of the underside of the arch. This
is known as a centre or centring. The voussoirs are laid on
it until the arch is complete and self
-
supporting. For an
arch higher than head height, scaffolding would in any case
be required by the builders, so the scaffolding can be
combined with the arch support. Occasionally arches would
fall down when the frame was removed if construction or
planning had been incorrect. (The A85 bridge at Dalmally,
Scotland suffered this fate on its first attempt, in the
1940s). The interior and lower line or curve of an arch is
known as the
intrados
.

Old arches sometimes need reinforcement due to decay of
the keystones, known as
bald arch
.

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Technical
aspects

1.
Advantages

2.
Disadvantages

1.
Advantages


Arches provide a structure which
eliminates tensile stresses in
spanning an open space.


Arches take advantage of the
strength under compression of
several construction materials:
stone, cast iron and concrete (all can
strongly resist compression but are
very weak in tension).


An arch can achieve significant
width, due to the compressive forces
that hold it together in balance.


Arches can be built with materials of
frictionless surfaces.

2.
Disadvantage


An arch needs to be restrained in
the base either with heavy sides
and friction or angled cuts,
because in this point the arch
forces push outwards, this also
happens in other varieties of this
structure such as in Arch dams.


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Types of
arch

1.
According to the shape

2.
Other types of arches

Triangular Arch

Round Arch

1.
Arches according to the shape


Segmental arch


Unequal round arch


Lancet Arch

Equilateral pointed Arch

Shouldered flat Arch

Three
-
foiled cusped
arch


2.
According to the centers


Horseshoe arch


Three centered arch


Elliptical arch


Inflexed arch


Ogee arch


Reverse ogee arch

3.
Other types of arches

Is an arch
-
like construction
method that uses the
architectural technique of
corbeling

to span a space or
void in a structure, such as an
entranceway in a wall or as the
span of a bridge.

A corbel arch is constructed by
offsetting successive courses
of stone at the spring line of
the walls so that they project
towards the archway's center
from each supporting side,


Corbel arch

Disadvantages of the corbel
arch


1.
Corbeled arches are not
entirely self
-
supporting
structures, and because of is
called a "false arch".

2.
Unlike "true" arches
, not all
of the structure's tensile
stresses caused by the weight
of the superstructure are
transformed into compressive
stresses.

3.
Corbel arches require very
thick walls and an abutment of
other stone or fill to counteract
the effects of gravity, which
otherwise would tend to
collapse each side of the
archway inwards



Mycenae, Greece


Maya Corbel Arch

Blind arch

Is an arch found in the
wall of a building, it
cannot serve as a
passageway, door, or
window. Some blind
arches were originally
built as open arches
and filled in later.
Others were originally
built with solid infill as
intentional stylistic
elements.



Arch Dam


Is a thin, curved
concrete or masonry
dam structure, that
generally has steel rods
or steel cables
reinforcements. This
structure is built to
curve against the water
so that its force
squeezes the arch,
compressing and
strengthening the
structure. An arch dam
is a good dam type for a
narrow valley in a
mountainous area.



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Arches built
with different
materials


Brick Arches

there are several types, for
example:

1.
The soldier arch,

2.
The ringed arch,

3.
And many other


1.
Soldier arch

This is a square shaped arch
which is purely decorative
and non load bearing.

It is used to cover the
reinforced lintel or rolled
steel joist that bears the
weight of the wall from
above and which is placed
behind it




2.
Ringed arch



This is the simplest type of
rounded arch to construct
since it involves no
complex geometry or
cutting of bricks to fit the
design.

It is semi circular in shape
with all of the bricks
facing inwards towards
the centre of the arch.


Stone Arches



1.
Keystone

2.
Voussoir

3.
Back

4.
Impost

5.
Intrados

6.
Rise

7.
Clear span,
"Bay"

8.
Abutment




Westford arch bridge


Metal Arches

These variety of arches are design
under different principle than the
stone arches, due to the
characteristic of metals of being
strong in tension as in compression




The Getaway Arch:
It is a hollow structure built with reinforced concrete
and stainless steel from the ground to the 91 meter and with carbon steel and
rebar from this point to the peak

Saint Louis, Missouri


Wembley Stadium, London:
this arch

is made of steel tubes, it has 133 m. high
and it supports 5000 tones of the roof structure, replacing the need for pillars so
everybody in the stadium would have a great view. This arch also make it possible to
retract the south part of the roof allowing air and light to enter.



Gateshead Millennium Bridge, Newcastle, England.
is a pedestrian and
cyclist tilt bridge spanning the River Tyne in England between Gateshead on the south
bank, and Newcastle upon Tyne on the north bank. The award
-
winning structure was
conceived and designed by architects Wilkinson Eyre and structural engineers Gifford.


The Tyne Bridge Arch, Newcastle, England

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More
examples


Roman Coliseum


Dominican Republic, Altagracia’s Church


Photo Researchers, Inc./Blair Seitz

Microsoft ® Encarta ® 2006.

© 1993
-
2005 Microsoft Corporation. Reservados todos los derechos.


Taj Mahal, India


Palatine Chapel


St. Michael Church, Hildesheim, Germany

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Victory
Arches


Washington Square Arch, New York


Victory Arch, Madrid, Spain


Bará’s Arch


Constantine’s Arch, Rome


Carabobo’s Arch, Venezuela


Arc De Triomphe, Paris

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Conclusion

Arches are self supported and very versatile
structures, that with the proper calculation
would hold large amounts of weight. It is a
structure very appealing aesthetically and
in the most cases has a important function.
Is also very common that arches would be
use as statements, symbols of greatness as
in Victory arches

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The End