The
Chicago School Of Architecture
Methods
And Materials : Research
HISTORY
FIREPROOFING FOUNDATION
FRAME ELEVATOR
A
Brief History of the Chicago School
In 1871, the great fire occurred in Chicago. Before the fire, buildings
were made from wood and timber; which consequently led to the fire that
led Chicago in ruins. A lesson a taught and soon, the Chicago school of
Architecture was established. This architectural movement brought up ideas
for improvement in buildings, and architects and engineers worked together
for the first time to rebuild the city. This change led to the skyscraper
generation. This movement influenced modern architecture.
Fireproofing
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Fireproofing depended upon the extensive use of stone, brick or cast or
wrought-iron.
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Heated stone usually crack and scales, especially when cold water hits
it, and heated metal turns ductile and melts.
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Only brick offers fireproofing possibilities, along with metal frame structure
encased behind the fireproofing.
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The Nixon Building, which a fire struck in 1871, had no damages against
the primary structures. (ie. exterior walls, and frames). The 5 storey
building was designed for maximum fireproofing; the walls were heavy
masonry construction, the interior frame was composed of cast-iron columns
and girders, the floor-framing system was covered with 1 inch-layer of
concrete and the ceilings were protected by an inch thick of plaster. It
became the model of the new fire resistant building.
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The most innovation in fireproofing was the hollow-tile construction for
sub flooring and partitions. Fired clay or terra-cotta skin was a good
fireproofing material when wrapped on the metal frames. It insulates the
property when dead air spaces existed between the skin and the structure,
which prevented the iron behind it from melting and buckling.
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Advances in heating, ventilation and plumbing complemented experiments
in fireproofing and structure.
Foundation
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Depends upon the soil, where it is built. Most durable when built upon
rock. (rock, clay sand or gravel will determine what kind of foundation
used)
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The foundations of high building are divided in 2 categories:
CONTINUOUS FOUNDATION
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Are solid uninterrupted walls, carried wholly or in part around the building.
They may rest on the earth or rock; on piles or on beds of concrete.
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Soils must have sufficient density to support the applied weight.
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Foundations on piles are not used in large buildings, and on concrete is
not frequently built.
ISOLATED FOUNDATION
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Was devised to distribute heavy loads of high buildings on earth foundations
over a wide area (distribution of weight in an economic manner).
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They were formed of piles, brick/concrete/stone footings, beams/rails and
caissons.
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The conditions of Chicago soil (wet/sandy/spongy soil) requires a floating
raft of concrete reinforced with steel rails, stepped up to receive the
wall or the bearing plate at the column foot.
a) The advantages for using the raft systems are: saving
space, a steel foundation is much lighter in weight which permits the addition
of an extra storey to the building and sufficient to carry the heaviest
buildings.
b) Disadvantages: steel foundations cost more than stone
ones.
Skeleton
Structure / Frame
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Born in Chicago, the construction method consisted of iron or steel columns,
with twin curtain walls between, in place of solid brick wall. The old
method of frame was the 'balloon frame' which was timber columns and beams.
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The curtain walls were carried on wrought iron or rolled steel girders
spanning the distance between the columns (about 15 feet).
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The weight of floors was also transmitted to the columns, so it supported
the entire building and contents.
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Columns were encased with brickwork when building was plastered.
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Optimum height per storey: 10 feet 6 inches. The loads and soil conditions
determine the framing members.
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The technique of combining cast-iron columns and wooden beams was standard
during the 1870?-80?. It Began the use of iron and steel framing in Jenney?
Home Insurance Building: it was the 1st tall elevator building to be supported
by a fireproofed metal frame. (known as the 1st skyscraper)
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The skeleton construction meets the following criteria: maximum admission
of natural sunlight, maximum durability and fire-resistance cost effective
and open interior space for maximum freedom. This new architectural style
was called 'Commercial Architecture'
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The use of iron framing was achieved after the Home Insurance Building.
In a framed building, the curtain wall has only a protective function.
A finished building of skeletal construction can be reduced to nothing
more than a framework covered with glass, as many today are.
Elevator
Building
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Most buildings were 5 storeys in height, but convinced the owners of the
advantage of the power-driven elevator.
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First steam-driven elevator used in 1864, the hydraulic elevator in 1870,
then was replaced by the electric elevator in1887.
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The popularity and success of the elevator building led to the increase
in the number of storeys. The rise in height changed the form of the buildings,
as the materials were made from brick, dressed stone, plain concrete, cast
iron and wood. These buildings had large windows and unadorned wall surfaces.
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The exterior walls of an elevator building were generally solid masonry
and the interior were made from iron columns and timber joist. The building
height was roughly proportional to the speed and safety of the elevator
and the thickness of the masonry walls gave the height.
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The typical elevator building had these descriptions (above), but ended
after the development of the skeleton structure.
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For easiest access, the elevators are concentrated in 2 central areas flanking
the entrance hall.
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The use of the elevator reversed the rental hierarchy (used to cost more
at ground level and lower storeys).
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Early elevators were low in movement, and frequently getting out of order.
Improvements followed with greater speed with absolute safety. It taught
men to build higher and higher: without elevator, a high building is impractical.