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DEATHQUAKE;
THE WAY OUT
Making
Them Safer
When an
earthquake occurs it causes vibratory ground motions in three different
directions that make buildings sway drunkenly and can be fatal to massive
concrete high-rises.
WHY
BUILDINGS FALL
Quake vibrations
are so intense that they turn soil into a jelly. The violent ground motion
pushes the building rapidly from one direction to another making it difficult
for the superstructure to constantly balance its load. Result: While columns
can bend, if the swaying motion intensifies they snap like matchsticks
and collapse.
CORE
COMPETENCE
Like a powerful muscle, a concrete core such as a lift-shaft, along with
concrete walls, holds up the adjoining structure during a quake.
BEAM
THEM IN
Concrete lintel beams above doors and windows bind the walls and prevent
them from flying out
Plinth beams
of concrete tie the columns into a composite that is more stable.
MOBILE
FOUNDATIONS
Seismic bearings under the foundation allow the building to shift several
inches with the ground movement. Shock absorbers-bearings with layers
of steel and rubber-also absorb the sideways motion.
SMART
BARS
A concrete
slab raft foundation is more difficult to sink in an earthquake, as the
pressure gets spread over a much greater surface area.
Corners
of walls are subject to enormous stress. A steel bar bound to the edges
with concrete allows the structure to withstand it.
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