DESIGN AND RETROFITTING OF STRUCTURES IN SEISMIC ZONES BY MEANS OF BUOYANCY

CONCEPTION ET REHABILITATION DE STRUCTURES DE ZONES SISMIQUES FAISANT APPEL A LA FLOTTABILITE

English Abstract

This invention comprises the use of buoyancy forces to counter, in whole
or in part, the gravity forces to which structures, such as buildings and
bridges,
are subjected during earthquakes.
It also comprises the retrofitting of existing structures, such as buildings
and bridges, in zones of high seismicity, by introducing the forces of
buoyancy
to counter the gravity forces to which these structures are subjected.
Present practice is to accept the seismic forces at ground level and to
design structures to resist the inertial forces to which they are subjected
during seismic activity.
The concept of the present invention is to deal with the problem at the
source; i.e., at ground level, thus eliminating, in whole or in part,
the necessity for dealing with the problem within the structures.

Claims

CLAIMS
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A system for use in supporting a structure, including a
sub-structure, located in a seismic zone, the system comprising:
a watertight basin located beneath and around the substructure,
the watertight basin containing water or any other buoyant matter
in which the substructure is located;
the substructure displacing a volume of the buoyant matter which
thereby exerts a buoyant force on the substructure, the force being
of a magnitude equal to at least a part of the dead load of the
structure;
flexible bearing pads located beneath the substructure, permitting
relative lateral movement between the substructure and the basin
during an earthquake.
2. A system as defined in claim 1 wherein the buoyant force equals
the dead load of the structure.
3. A system as defined in claims 1 or 2 wherein the structure is a
high-rise building.
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4. A system as defined in claims 1 or 2 wherein the structure is a
bridge with piers and abutments and the basin is an existing body
of water.
5. A system as defined in claims 1 or 2 wherein the structure is a
bridge with piers or abutments on dry land and the watertight
basins are added beneath and around the piers or abutments.
11

Description

2187465
TECHNICAL FIELD
The technical field of the present invention is the structural response
to earthquake forces.
BACKGROUND OF THE INVENTION
Present practice is to dampen seismic forces by means of mechanical
devices, and to deal with the balance of the seicmic forces by reinforcing the
structure.
The philosophy of the present invention is to deal with the entire
problem by displacing the weight of the structure in a liquid, such as water,
thus effectively lowering the centre of gravity of the structure to an extent
that substantially reduces the effects of seismic forces on the structure.
SUMMARY OF THE INVENTION
The present invention has the effect of considering a new structure as a
quasi-boat, and converting an existing structure in seismic zones, to a quasi-
boat, rendering the structure considerably less sensitive to seismic forces.
It is important, however, that the extent of displacement of the structure
by liquid is limited to an amount that allows stability due to wind forces;
i.e.,
there must never be a negative reaction at the base of a structure due to wind
forces.
_.---,~''"~ 2

BRIEF DESCRIPTION OF THE DRAWINGS _ 218 7 4 6 5
In the drawings submitted:
Figure 1 shows a cross-sectional elevation of a high-rise building in a
seismic zone;
Figure 2 shows a detail at the base of the building
Figure 3 shows a plan view of the building
Figure 4 shows a viaduct pier in a seismic zone
Figure 5 shows a detail of the base of a viaduct pier in a seismic zone
Figure 6 shows a plan view of a viaduct pier in a seismic zone
Figure 7 shows a retrofit of a viaduct pier in a seismic zone
Figure 8 shows a detail at the base of a retrofitted viaduct pier in a
seismic zone
Figure 9 shows a plan view of a retrofitted viaduct pier in a seismic zone
Figure 10 shows a bridge [over water] pier in a seismic zone
Figure 11 shows a detail of the base of a bridge [over water] pier in a
seismic zone
Figure 12 shows a plan view of a bridge [over water] in a seismic
Figure 13 shows a retrofit of a bridge [over water] pier in a seismic zone
Figure 14 shows a detail at the base of a retrofitted bridge [over water]
in a seismic zone
Figure 15 shows a plan view of a retrofitted bridge [over water] pier
in a seismic zone
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2187465
Figure 16 shows a sectional elevation of a retrofitted high-rise building
in a seismic zone
Figure 17 shows a detail at the base of a retrofitted high-rise building
in a seismic zone
DETAILED DESCRIPTION
This invention is illustrated by way of four examples:
The first illustrative example is shown in Figures 1, 2 and 3, wherein:
_1 is a high rise building
is the basement of the building
is a watertight basin, into which will be introduced water or any
other buoyant matter
_4 is water, or any other buoyant matter, introduced into the water-
tught basin after construction of the building
is an access bridge
is optional decking, to cover the water and for aesthetic reasons
.Z is a bearing pad placed upon the basin slab prior to construction
of the building; said bearing pad having flexibility for lateral
movement with optional sliding plate material, to permit the lateral
displacement of the basin during a strong earthquake, while leaving
the building structure in its original position
4

?.18146
The second illustrative example is shown in Figures 4 through 9:
Figures 4 through 6 showing new construction, and Figures 7 through
9 showing a retrofit of an existing construction; wherein,
in Figures 4 through 6:
$ is a Viaduct Pier or Piers
.Q is its footing
~,Q is a watertight basin around the footing
11 is the structural connection between the Pier or Piers and the
footing
~? is lightweight buoyancy material, such as STYROFOAM, within the
footing
is a bearing pad placed upon the basin slab, said bearing pad
having flexibility for lateral movement with optional sliding plate
material, to permit the lateral displacement of the basin during a
strong earthquake, while leaving the Pier or Piers in its, or their,
original position
is water, or any other buoyant matter

2187465
in Figures 7 through 9:
1~ is a retrofitted Viaduct Pier or Piers
is its [retrofitted] footing
l~ is a watertight basin around the footing
~$ is the structural connection between the Viaduct Pier or Piers
and the footing
1~ is lightweight buoyancy material, such as STYROFOAM, within the
footing
2~ is a bearing pad placed upon the basin slab, said bearing pad
having flexibility for lateral movement with optional sliding plate
material ~, to permit the lateral displacement of the basin during
strong earthquake, while leaving the Viaduct Pier or Piers in its,
or their, original position
is water, or any other buoyant matter
is an existing footing
2~ is the severed portion of an existing Viaduct Pier, or Piers, wherein
the load from the Pier or Piers is transferred from the existing
footing ~, to the retrofitted footing "~
y
6

z ~ 8~46~
The third illustrative example is shown in Figures 10 through 15;
wherein the Bridge footings are submerged within a body of water
or any other buoyant matter:
Figures 10 through 12 showing new construction, and Figures 13
through 15 showing a retrofit of an existing construction; wherein:
in Figures 10 through 12:
~5 is a Bridge Pier or Piers
is its, or their, footing
is a sub-footing levelling concrete pad
?$ is a structural connection between the Pier or Piers and the
footing ~,ø
2~ is lightweight buoyancy material, such as STYROFOAM, within the
footing
is a bearing pad placed upon the sub-footing levelling concrete
pad .~Z
LWL is the low water level of a body of water, or other buoyant matter
y
7

z ~ s146~
in Figures 13 through 15:
~1 is a retrofitted Bridge Pier or Piers
is its, or their, new (retrofitted] footing
is an existing footing
is a structural connection between the Pier or Piers and the new
retrofitted footing ~
is lightweight buoyancy material, such as STYROFOAM, within the
new (retrofitted] footing ~
is a bearing pad placed upon the top surface of the existing footing
is the severed portion of an existing Bridge Pier or Piers, wherein
the load from the Pier or Piers is transferred from the existing
footing ~ to the retrofitted footing ~ by way of the structural
connection ~
LWL is the low water level of a body of water, or other buoyant matter
G
8

z ~ ~~4b~
The fourth illustrative example shows a retrofit of an existing high-rise
building, wherein, in Figures 16 and 17:
~$ is an existing high-rise building
are existing footings
4~ is a new attachment, for retrofit purposes, to the building,
completely surrounding it
is a new watertight basin
is lightweight buoyancy material, such as STYROFOAM, within
the new attachment ~Q
is pea gravel, or similar material
44 is a bearing pad placed upon the basin slab, said bearing pad
having flexibility for lateral movement with optional sliding plate
sandwiched within the bearing pad, to permit the lateral
displacement of the basin during a strong earthquake, while leaving
the Building in its original position.
is water, or any other buoyant matter
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Representative Drawing