Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
WO 95134724 219 2 ~ 6 7 PCT~S95/069Z1
1
HIGH STRENGTH FABRIC REINFORCED WALLS
BAGRGROVND OF THE INVENTION
Field of the Invention
The present invention relates generally to
reinforcing walls to increase their ability to withstand
atypical loads such as those encountered during
earthquakes. More particularly, the present invention
relates to a method for increasing the ductility and
strength of a Wall in situ without removing the wall from
service and without the need to provide auxiliary support
during the repair process.
.~ Desariotion of the Reiated Art
Recent earthquakes have revealed that many existing
walls lack sufficient strength and ductility to withstand
moderate to severe earthquakes. Moderate quakes have
caused all types of load-bearing and non-load bearing
walls to crack while stronger quakes at times have
resulted in the total failure of such walls.
Because the collapse of walls can have disastrous
consequences,it has become a common practice in the
2o construction of certain walls, e.g., cellular brick or
concrete walls, to reinforce the walls with metal rods or
bars. However, there are hundreds of thousands of
existing in earthquake-prone areas which do not have
adequate metal reinforcement and which were not designed
to withstand high degrees of atypical loading.
Furthermore, while metal reinforcement provides added
structural strength to walls, metal-reinforced walls also
have been known to crack or fail when subjected to
atypical loadings generated during earthquakes.
In most cases, the replacement of existing walls with
walls having greater strength and ductility is
economically impracticable. Accordingly, there is a need
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2
to provide a simple, efficient and relatively inexpensive
method for reinforcing walls so as to prevent or reduce
the likelihood of failure during an earthquake. One
example of a,method for increasing the structural strength
of existing structures without their removal from service
is set forth in United States Patent No. 5,043,033, issued
to Fyfe. In this particular patent, the surface of a
concrete column is wrapped with a composite material to
form a hard annular shell surrounding the concrete column.
The space between the outer composite shell and the
concrete column is then pressurized by injecting a
hardenable liquid.
Another approach to reinforcing the exterior of an
existing concrete support column without removing it from
service is set forth in United States Patent No.
5,218,810, issued to Isley, Jr. In this patent, the
exterior surface of a concrete column is wrapped with a
composite material to form a hard annular shell or sleeve
which is in direct contact with the column surface.
While these approaches may be well suited to the
reinforcement of existing structures which can be
completely surrounded by a composite shell, i.e., columns,
they do not account for the problems associated with
reinforcing certain structures, i.e., walls, wherein it is
structurally or economically infeasible or impracticable
to form a unitary composite shell about the exterior of
the structure.
For instance, a unitary composite shell cannot be
formed around the portions of exterior or interior walls
which include windows, doors, or other structural
discontinuities provided for the ingress or egress of
light, air, or people. Accordingly, there remains a need
for a fast, efficient, and cost-effective way to reinforce
walls so as to increase their resistance to structural
failure during earthquakes.
CA 02192567 2005-03-22
A
3
SUMMARY OF THE INVENTION
In accordance with the present invention, a simple,
fast, efficient and cost-effective method is provided for
reinforcing the face or faces of walls so as to prevent or
reduce the likelihood of failure when such walls are
subjected to atypical loadings such as are encountered
during earthquakes.
The present invention is based upon the discovery that
the resistance of walls to structural failure can be
increased by applying at least one fabric layer impregnated
with resin over the exposed face or faces of such walls.
The present invention is based on the further
discovery that a wall which includes an overlying composite
reinforcement layer is less likely to fail if the composite
reinforcement layer is attached or otherwise anchored to a
structural member of the underlying wall.
Accordingly, the present invention provides a
reinforced wall comprising: a wall having at least one
face; a reinforcement layer overlaying at least a portion
of said face, said reinforcement layer comprising at least
one fabric layer impregnated with resin; and a fastener
comprising a fabric member which extends through said face
into or through said wall for anchoring said reinforcement
layer to said wall.
In a further aspect, the present invention provides a
method for reinforcing walls comprising the steps of:
applying a fabric layer over a portion of a face of a wall;
impregnating said fabric layer with a curable resin to form
a resin-impregnated fabric layer; affixing an anchor
comprising a fabric member into or through said wall; and
affixing said anchor to said reinforcement layer.
CA 02192567 2005-03-22
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The method of the present invention can be used to
reinforce different wall types including single component
walls such as concrete slab type walls, multi-component
walls such as brick walls, and studded or other walls which
are provided with an overlying facia.
Means are provided for anchoring the reinforcement
layer to the wall. The anchoring means to be provided may
vary greatly depending a variety of factors including the
type of wall to be reinforced, the costs associated with
different methods for anchoring the composite reinforcement
layer to the wall, and aesthetic concerns relating to the
appearance of the wall to be reinforced.
For concrete slab walls, brick walls and other walls
wherein the exposed face of the wall comprises a portion of
the wall structural member, as a feature of the present
invention, the composite reinforcement layer is anchored to
the wall using an adhesive resin or other adhesive product.
For walls including an overlying facie which is
provided principally for reasons other than added
structural strength, as an alternative feature of the
present invention, the composite reinforcement layer is
anchored to an underlying structural member using a
fastener which extends through the face of the wall into,
through or around the structural member.
As yet one more feature of the present invention, an
anchor retention device such as pin or plug is provided
which cooperates with the fabric member to anchor the
composite reinforcement layer to the structural member.
As another feature of the present invention, at least
one resin-impregnated fabric layer includes a pair of
horizontally extending selvedges.
CA 02192567 2005-03-22
4a
As an alternative or additional feature of the present
invention, at least one resin-impregnated fabric layer
includes a pair of vertically extending selvedges.
As yet another feature of the present invention, the
composite reinforcement layer includes a plurality of high
strength, substantially horizontally extending warp yarns
and a plurality of lower strength, higher elongation,
substantially vertically extending fill yarns.
As yet an additional feature of the present invention,
the high strength warp yarns are selected from the group of
materials including glass, polyaramid,
WO 95134724 219 2 5 6 7 PCTIU595I06921
,. 5
graphite, silica, quartz, carbon, ceramic, polyethylene,
polyimide, liquid crystal polymers and polypropylene and
the lower strength high elongation fill yarns are selected
from the group of materials ii:~luding polyester and nylon.
As an additional or alternative feature of the
present invention, at least one resin-impregnated fabric
layer includes a plurality of plus bias angle yarns which
extend at an angle between zero and ninety degrees
relative to the selvedges and a plurality of minus bias
angle yarns which extend at an angle of between minus zero
to minus ninety degrees relative to the selvedges.
As yet an additional feature of the present
invention, the resin in the composite reinforcement layer
is impregnated with an intumescent or a low temperature
melting glass suitable for rendering the composite
reinforcevn.ent layer fire resistant.
As yet one more feature of the present invention, a
hardenable low shrink material is injected between the
composite reinforcement layer and the wall face so as to
provided further reinforcement for the wall.
The above-discussed features and many other features
and attendant advantages of the present invention will
become better understood by reference to the following
detailed description when taken in conjunction with the
accompanying drawings.
$RIEF DESCRIPTION OF TH8 DRAWINC;B
FIG. 1 shows the face of an exemplary preferred
reinforced wall in accordance with the present invention.
FIG. 2 is a partial side section of an exemplary
preferred reinforced wall in accordance with the present
invention showing a first preferred exemplary anchor.
FIG. 3 is a partial side section of an exemplary
preferred reinforced wall in accordance. with the present
invention showing a second preferred exemplary anchor
including a substantially inflexible pin.
WO 95134724 ~ ~ PCT/US95106921
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FIG. 4 is a plan section of the pin shown in FIG. 3.
FIG. 5 is a side section of an exemplary preferred
reinforced wall showing a third preferred exemplary
anchor.
FIG. 5A is a partial plan section of the exemplary
preferred reinforced wall of FIG. 5 taken in the direction
of arrows 5A-5A.
FIG. 6 shows the face of an alternative exemplary
preferred reinforced wall wherein the fabric layer only
to covers a portion of the subject wall.
FIG. 7 is a demonstrative representation depicting
the impregnation of a fabric layer prior to application to
the face of a wall.
FIG. 8 is a detailed sectional view of a preferred
exemplary fabric layer in accordance with the present
invention.
FIG. 9 is a detailed sectional view of an alternative
preferred exemplary fabric layer in accordance with the
present invention.
FIG. 10 depicts a weave pattern which is the same as
the weave pattern shown in FIG. 9 except that the yarns
are stitch bonded together.
FIG. 11 is a detailed partial section of the face of
a reinforced wall covered with multiple fabric layers.
FIG. 12 depicts unidirectional fabric which is stitch
bonded and may be used as a fabric layer in accordance
with the present invention.
FIG. 13 depicts the unidirectional stitch bonded
fabric of FIG. 12 in combination with a second layer of
diagonally oriented unidirectionally oriented fabric.
FIG. 14 depicts an alternative fabric layer
arrangement wherein two diagonally oriented units
directional fabrics are stitch bonded together.
FIG. 15 is a sectional view of FIG. 14 taken in the
15-15 plane.
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DETAINED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention may be used to reinforce a wide
variety of walls. The invention is especially well-suited
for reinforcing walls wherein it is structurally
infeasible or economically impracticable to wrap the wall
face with a composite reinforcement layer so as to form a
unitary composite shell around the wall.
A preferred exemplary reinforced wall in accordance
to with the present invention is shown generally at 10 in~
FIGS. 1. The face (not shown) of the underlying wall is
completely covered by a composite reinforcement layer
which is shown generally at 12. Composite reinforcement
layer 12 is made up of three fabric layers 14, 16 and 18.
Each of the fabric layers 14 through 18 has first and
second parallel selvedges which, preferably, extend
substantially horizontally as shown in FIG. 1. The first
and second selvedges for fabric layer 14 are shown at 20
and 22. The first and second selvedges for fabric layer
16 are.shown at 24 and 26, respectively. The first and
second selvedges for fabric layer 18 are shown at 28 and
30, respectively.
As stated above, the method of anchoring the
composite reinforcement layer to the underlying wall may
vary greatly depending a variety of factors including the
type of wall to be reinforced, the costs associated with
different methods for anchoring the composite
reinforcement layer to the wall, and aesthetic concerns
relating to the appearance of the wall to be reinforced.
Referring now to FIG. 2, a partial side section of a
first exemplary preferred reinforced wall 40 is shown.
Reinforced wall 40 includes a thick concrete slab
structural member 42, a relatively thin outer layer or
facie 44, face 46, and composite reinforcement layer 48.
The reinforced wall 40 also includes a plurality of fabric
fastener. or anchors 50 (only one which is shown) and
wo 9sisa~2a
~ 7 9 2 5 6 l PCT~S95/06921
8
corresponding anchor receiving cavities 52 (also only one
of which is shown).
The reinforced wall 40 of FIG. 2 is formed by
drilling holes through facie 44 and into the structural
member 42 so as to define anchor receiving cavities 52.
Anchor receiving cavities 52 are provided with sufficient
depth to receive and hold fabric fasteners 50. Cavities
52 are distributed about the portion of face 20 to be
reinforced so as to facilitate the anchoring of the edges
and selected intermediate portions of each fabric layer-
comprising composite reinforcement layer 48. It is
preferred that adjacent anchors be spaced evenly about the
wall face at a density of between about 0.1 and 2.0
anchors per square foot. However, those.skilled in the
art will understand that the preferred distribution and
density of anchors will vary depending on many factors
including the thickness and density of the composite
reinforcement layers, the strength of adhesive, if any,
binding the composite reinforcement layer 48 to face 46,
and the desired properties of the wall to be reinforced.
Fabric fasteners 50 are preferably configured as
sleeves or strips to be inserted into cavities 52. Fabric
fasteners 50 include engagement portions 54 which, in the
preferred embodiment shown in FIG. 2, adjoin face '46 and
composite reinforcement layer 48. Each fabric fastener 50
also includes an anchored portion 56 which extends into a
cavity 52 and adjoins structural member 42.
After cavities 52 are formed, fabric fasteners 50 are
partially inserted into cavities 52 so as to seat anchored
portions 56 within cavities 52 against structural member
42. The anchored portions 56 are preferably impregnated
with an adhesive resin or other adhesive product. Once
the resin-impregnated anchored portions 56 are positioned
within cavities 52, a plug 58 is used to wedge the
anchored portion 56 of each fabric fastener 50 into
engagement with structural member 42. Plug 58 is
W O 95134724 21.9 2 5 6 l PCT~595/0692I
9
preferably formed from an elastomeric substance, e.g.,
rubber, which is compatible with the resin or other
material in which anchored portions 56 are impregnated.
The space between the plug 58 and composite reinforcement
layer 48 can be filled with a suitable filler 60 such as
resin, putty or a speckling compound.
While the use of an in situ plug in the anchoring
system shown in FIG. 2 is generally preferred, the
anchoring of anchored portions 56 may be accomplished
l0 without the use of an in situ plug by impregnating the
anchored portions 56 with a'resin which will adhere to the
structural member 42 upon curing.
Alternatively, the anchored portions 56 may be
impregnated with a hot melt adhesive or another suitable
adhesive. Impregnation of the anchored portions 56 in a
hot melt adhesive may be accomplished using a hot melt
glue gun. Alternatively, a pre-formed hot melt plug can
be used instead of rubber plug 58 to seat anchored
portions 56 in cavities 52 in which case the hot melt
adhesive is melted in place by injecting hot air into
cavities 52 or using other suitable means. Anchored
portions 56 may also be pre-impregnated with a hardened
hot melt adhesive which is heated after the anchored
portions 56 are seated within cavities 52.
After anchored portions 56 are seated within cavities
52, the fibers which extend outward from face 46 are
partially or totally separated and then wet out with the
preferred resin (if not wetted out already) to form
engagement portions 54 and fanned out against face 46 of
facie 44 as best shown in FIG. 2. Alternatively, fabric
members 22 can be attached to face 46 or outer surface 62
using a hot melt or other suitable adhesive. (Where the
fabric members are attached directly to the fabric layer
using a hot' melt adhesive, it is preferable to melt the
adhesive and allow it set up before impregnating the
fabric layer with resin).
R'O 95!34724 2 1 9 2 5 6 7 P~~S95106921
Thereafter, one or more fabric layers comprising
composite reinforcement layer 48 are applied to face 46
preferably but not necessarily with the selvedges
extending substantially horizontally in the manner shown
5 in FIG. 1.
In an alternative preferred method (not shown) for
anchoring composite reinforcement layer 48 to structural
member 42, the fabric layers of composite reinforcement
layer 48 are provided with apertures corresponding to
10 anchor receiving cavities 52. Upon placing the fabric
layers in the desired positions against face 46,
engagement portions 54 are drawn through the apertures and
fanned out against the exposed outer surface 62 of
composite reinforcement layer 48.
Each fabric layer of a composite reinforcement layer
48 must. be impregnated with resin in order for composite
reinforcement layer 48 to function properly in accordance
with the present invention. It is generally preferable to
impregnate the fabric layers with resin prior to
application to face 46. of the wall 40. However, if
desired, the resin may be impregnated into the fabric
layers after the fabric layers are laid against face 46.
Suitable resins for impregnating the fabric layers
and the fabric members in accordance with the present
invention include polyester, epoxy, vinylester, acrylic,
modified acrylic, urethane, phenolic, polyimide,
bismaleimide, urethane, polyurea, or combinations thereof,
with epoxy being a preferred resin. Other impregnating
resins may be utilized provided that they have the same
degree of strength and toughness provided by the
previously listed resins. In most applications, thermoset
resins are preferred. However, enhancements to process
will allow the use of thermoplastic resin systems.
It is often desirable though not necessary to coat
the portion of wall 40 to be reinforced with a preferred
resin before application of the resin-impregnated fabric
W O 95!34724 ~' 19 2 5 6 7 PC'I'/11595/0692I
11
layers to the wall. If the wall surface is porous, it may
be desirable to allow the resin to penetrate the wall
surface before applying the resin-impregnated fabric
layers to the wall.
If the face of the wall is uneven or irregular or
extra adhesion is desired, vacuum bagging techniques well
known in the arts can be used to draw the fabric layers
towards the wail face to enhance conformability to the
wall surface and to remove air which might be trapped
therebetween.
It is preferred that the exterior face be thoroughly
cleaned prior to application of the impregnated fabric
layers. The exterior face should be sufficiently clean so
that the resin matrix will adhere to the face of the wall.
While bonding of the resin matrix and the composite
reinforcement layer to face 46 is preferred, it is not
essential since the composite reinforcement layer 48 is
anchored to the structural member 42.
Curing of the resins is carried out in accordance
with well known procedures which will vary depending on
the particular resin matrix used. various conventional
catalysts, curing agents and additives which are typically
employed with such resin systems may be used.
Once the resin. is cured, the combination of the
fabric layers; the fabric members, and the cured resin
form an integral high strength composite. which is
permanently bonded (and thus anchored) to structural
member 42. Advantageously, the resin-impregnated fabric
members in the above describe wall are almost invisible
3o and thus the foregoing method is useful when aesthetic
considerations are important.
If desired, the exposed surface of the composite
reinforcement layer may be coated with a desired surface
protectant, e.g., paint, urethane, acrylic, etc. In
applications where it is preferable that the composite
reinforcement layer be resistant to fire, a commercially
WO 95/34724 219 2 5 6 7 PCT~S95106921
12 -
available coating such as FIREGUARD may be used.
Alternatively, the resin in the composite reinforcement
layer may be impregnated with an intumescent or a low
temperature melting glass suitable for rendering the
composite reinforcement layer fire resistant. The melting
glass preferably has a melting temperature of no more than
about 800 degrees fahrenheit.
If the structure to be reinforced is a historical
landmark, it may be necessary to allow the face . of the
structure to show through the composite reinforcement
layer. In such case, the preferred fabric layers should
be comprised of a material that is or becomes transparent
upon curing of the preferred resin. Fabrics suitable for
such purposes include E-glass woven, adhesively bonded,
unidirectionals and some stitch-bonded unidirectionals
with woven fabrics being preferred.
Resins suitable for such purposes include aliphatic
epoxy, in combination with linear amine cross linking
agents, acrylic, modified polyester and polyurethanes.
Other additives such as flow controllers (thixoprops),
ultraviolet inhibitors or stabilizers, flexibilizers,
etc., may also be required.
If the composite reinforcement layer in such
applications is to be coated, it is preferable to use a
transparent urethane or acrylic, or other "water white"
transparent materials with similar properties.
Referring now to FIG. 3, a partial side section of a
second exemplary preferred reinforced wall 70 is shown.
Reinforced wall 7o includes a plurality of relatively thin
stud-type structural members 72 (only one is shown) , an
outer layer or facia 74, face 76, and composite
reinforcement layer 78. The reinforced wall 70 includes
a plurality of fabric fasteners or anchors 80 (only one
which is shown) and corresponding anchor receiving
cavities 82 (also only one of which is shown).
The reinforced wall 70 of FIG. 3 is formed by
WO 95134724 2 1 9 2 5 b 7 P~~S95/06921
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drilling holes through facia 74 and into selected studs 72
so as to define anchor receiving cavities 82. In contrast
to the anchor receiving cavities of FIG. 2, cavities 82
extend through structural members 72 to the obverse side
83 of wall 70. ,
Fabric fasteners 80 include engagement portions 84
and 86 Which adjoin face 76 and composite reinforcement
layer 78. Each fabric fastener 80 also includes an
anchored portion 88 which extends through cavity 82 to the
obverse side 83 of wall 70. Anchored portion 88 is
anchored to stud 72 using a locking pin 90. Locking pin
90, as bast shown in FIG. 4, is preferably formed from a
stiff bar or rod having an aperture 92 for receiving
fabric fastener 80. As is shown in FIG. 3, the fabric
fastener 80 is looped through aperture 92 after which the
engagement portions 84 and 86 are pulled tight so as to
wedge the locking pin 90 against the obverse side 83 of
stud 72. The engagement portions 84 and 86 of the fabric
fastener 80 are then extended through anchor receiving
cavity 82 and fanned out across the front face 76 of the
wall in the manner described above.
As with the embodiment of FIG. 2, the fabric
fasteners 80 of FIG. 3 are distributed about the wall to
be reinforced so as to facilitate the anchoring of the
edges and selected intermediate portions of each fabric
layer comprising composite reinforcement layer. Those
skilled in the art will understand that the preferred
distribution and density of anchors will vary depending on
the factors discussed above and the spacing of the studs
forming the underlying structural member.
A third preferred exemplary wall is shown generally
at 100 in FIGS. 5 and 5A. Reinforced wall 100 includes
a structural member 102 having upper and lower edges 103A
and 103B, faces 104 and 106, and a composite reinforcement
layer 108 which completely covers face 104. The
reinforced wall 100 also includes a plurality of
W 0 95134724 PCT/US95l06921
z ~ 9z5~~
14
substantially elongate fabric straps 110. Fabric straps
110 include engagement portions 116 and 118 which adjoin
face 104 and composite reinforcement layer 108. Each
fabric strap 110 also includes an anchored portions 120
, which adjoins face 106 on the obverse side 122 of wall
100.
As is shown in FIGS. 5 and 5A, each fabric strap 110
is passed through a corresponding pair of spaced apart
anchor receiving cavities 112 and 114 after which the
engagement portions 116 and 118 are pulled tight so as to
wedge the anchored portion 120 against the obverse face
106 of wall 102. The engagement portions of the fabric
strap 110 are then attached to face 106 or composite
reinforcement layer 108 as described above. In
applications where obverse side 122 of.wall lO0 is faced
off with a facie, the anchored portion 120 of each fabric
strap 110 can be drawn against the exposed surface of such
. facie to effect the same anchoring function.
Preferably, anchor receiving cavities 112 and 114 are
positioned relative to the composite reinforcement layer
such that each fabric strap 110 overlays a portion of the
composite reinforcement layer extending between opposing
parametrial edges of the composite reinforcement layer.
The fabric straps (and the other fabric members
described above) may be formed from a suitable fabric
including woven or non-woven fabrics and unidirectional
tapes. However, the fabric straps are preferably formed
from a woven~fabric. It is preferred that fabric straps
110 be spaced evenly about the wall face at distances of
between about three to six feet. However, as discussed
above, those skilled in the art will understand that the
preferred distribution of anchors will vary depending on
many factors.
The fibers forming the fabric straps are preferably
made from the group of materials including glass,
polyaramid, graphite, silica, quartz, carbon, ceramic,
WO 95134724
219 2 5 6 7 p~T~s9sro69za
polyethylene, polyimide, liquid crystal polymers and
polypropylene. The fibers forming the fabric members
shown in Figs. 2-3 are preferably made from the group of
materials including, glass, polyaramid, graphite, silica,
5 quartz, carbon, ceramic, polyethylene, polyimide, liquid
crystal polymers and polypropylene, but may also be from
the group of materials including polyester and nylon.
In applications such as shown in FIG. 4 where a
composite reinforcemer~t layer is placed in direct contact
1o with the exposed face of a structural member, an
alternative method for anchoring a composite reinforcement
layer to the structural (not shown) involves the use of an
adhesive fastener such as an epoxy resin or another
suitable resin listed above. The adhesive fastener is
15 applied to the face of the structural member to be
reinforced and allowed to gel in the manner describe
above. Thereafter, resin-impregnated fabric layers are
applied to the face and allowed to cure so as to form a
composite reinforcement layer anchored to the underlying
structural member as described above.
It should be noted that a "structural member", for
purposes herein, includes structural members and any wall
member attached or otherwise anchored to a structural
member in such a manner as to enable a composite
reinforcement layer which is anchored to such wall member
to cooperate with such structural member in a manner
substantially equivalent to the manner in which the
composite reinforcement layer would cooperate with the
structural member if anchored directly thereto.
It should also be noted that facias, while typically
provided for reasons other than added structural strength,
may constitute a structural member. iVhether a facie
constitutes a structural member will depend upon the mode
of attachment of the facie, if any, to the underlying
structural member.
It is preferred that the fabric layers of a composite
wo ssr~a~aa 219 2 5 6 7 P~~S95I069a1
16
reinforcement layer be placed on the exterior face or
faces of a wall so that substantially the entire face or
faces are covered. However, in certain applications, it
may be desirable only to cover those portions of a wall
which are most likely, to fail during atypical loading,
e.g., the lower third of a wall. The partial
reinforcement of a wall 130 is shown in FIG. 6. Only the
lower third of the face (not shown) of the underlying wall
130 is covered with a composite reinforcement layer shown
generally at 132.
Referring now to FIG. 7, a fabric 140 is shown being
unwound from a roll 142 and dipped in resin 144 for
impregnation prior to application to the face of a wall.
Once a sufficient length of fabric 140 has been
impregnated within the resin 144, the impregnated fabric
layer is cut from the roll 142 and is applied to the face
of the wall. The length of the impregnated fabric is
chosen so as to cover those portions of the wall which are
most likely to fail during atypical loading. Once in
place, the resin impregnated fabric layer is allowed to
cure to form the composite reinforcement layer. The
impregnation and application process is repeated until the
selected portion of the wall has been covered as shown in
FIG. 1 or 6.
A preferred exemplary fabric layer is shown in FIG.
8. The width of the fabric between the selvedges may be
from 3 to 100 inches.. The fabric has warp yarns 162 and
fill yarns 164. The Warp yarns extend substantially
parallel to the selvedges, with the fill yarns extending
substantially horizontally to the selvedges. The fabric
is preferably a plain woven fabric but may also be a 2 to
8 harness satin or twill weave. This fabric configuration
provides reinforcement in both the warp and Eill
directions.
A preferred alternate fabric pattern is shown in FIG.
9. In this fabric pattern, plus bias angle yarns 170
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2192567
17
extend at an angle of between 0 and 90 degrees relative to
the selvedge 171 of the fabric. The preferred angle for
the plus and minus bias angle yarns is plus and minus 45
degrees relative to the selvedge 171. The plus bias angle
yarns 17o are preferably made from the same yarn material
as described in connection with the fabric shown in FIG.
8. The minus bias angle yarns 172 extend at an angle of
between 0 and minus 90 degrees relative to selvedge 171.
The minus bias angle yarns preferably extend substantially
perpendicular to the plus bias angle yarns. Preferably,
the plus and minus bias angle yarns are made from the same
yarn material. The number of yarns per inch for both the
plus and minus bias angles is preferably between about 5
and 30, with about 10 yarns per inch being particularly
preferred. Where it is desirable to increase the wall s
resistance to shear failure, the preferred angle for the
plus and minus bias angle yarns is plus and minus 45
degrees relative to the selvedge 171 (provided the fabric
is positioned over the wall such that selvedge,171 extends
substantially horizontally or substantially vertically.
The fibers forming the warp and fill yarns for the
fabric shown in FIG. 8 (and any other fabric layers
described herein) may be made from a wide of materials
including glass, polyaramid, graphite, silica, quartz,
carbon, ceramic, polyethylene, polyimide, liquid crystal
polymers or polypropylene. However, it is believed that
the use of high strength, horizontally extending yarns in
conjunction with lower strength, higher elongation,
vertically extending yarns increases the ductility and
strength of a wall and distributes horizontal cracking, if
any, between the load-bearing ends of the wall (or, if the
composite reinforcement layer does not extend between the
load-bearing ends of the wall, then between the upper and
lower ends of the gomposite reinforcement layer).
Accordingly, where the warp and fill yarns of the
preferred fabric extend substantially horizontally and
WO 95134724 ~ ~ PCTJUS95/06921
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vertically, respectively, across the face of a wall, it is
preferred that the warp yarns be formed from the group of
materials including (E-type and other high strength)
glass, polyaramid, graphite, silica, quartz, carbon,
ceramic, (ultra-high molecular weight) polyethylene,
polyimide, liquid crystal polymers and polypropylene
fibers and that the fill yarns be formed from the group of
materials including polyester and nylon fibers.
The diameters of such high strength fibers
preferably range from about 3 microns to about 30 microns.
The diameters of the lower strength, higher elongation
fibers preferably range from about 0.5 to about 10 deniers
per fiber. It is preferred that each warp yarn include
between 2 and 8000 fibers and that each fill yarn include
between about 1 and 2000 fibers. The number of warp yarns
per inch is preferably between about 5 to 20. The
preferred number of fill yarns per inch is preferably
between about 0.5 and 5Ø
It is preferred that the fabric weave patterns be
held securely in place relative to each other. This is
preferably accomplished by the stitch bonding of the yarns
together as shown at FIG. 10. An alternative method of
holding the yarns in place is by the use of an adhesive or
lenoweaving process, both are of which are well known to
those skilled in the art. In FIG. 10, exemplary yarns
used to provide the stitch bonding are shown in phantom at
173. The process by which the yarns are stitched bonded
together is conventional and will not be described in
detail. The smaller yarn used to provide the stitch
bonding may be made from the same-materials as the
principal yarns or from any other suitable material
commonly used to stitch bond fabric yarns together. The
fabric shown in FIG. 8 may be stitched bonded.
Also, if desired, a unidirectional fabric which is
stitched bonded may be used in accordance with the present
invention. Such a unidirectional stitch bonded fabric is
WO 95134724 . PCT/LTS95/06921
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shown in FIG. 12 at 179. The fabric includes
unidirectional fibers 180 which are stitch bonded together
as represented by lines 182.
The unidirectional stitch bonded fabric may be used
alone or in combination with other fabric configurations.
For example, a two layer fabric system is shown in FIG. 13
for an upper unidirectional stitch bonded layer 184 which
is the same as the fabric layer 179 is combined with a
diagonally oriented lower layer of unidirectional fibers
186. The lower fabric layer may or may not be stitch
bonded. The fabric layer 186 as shown in FIG. 13 is not
stitch bonded.
Another alternative fabric layer embodiment is shown
in FIGS. 14 and 15. In this embodiment, the upper layer
188 is a unidirectional fabric in which the fibers 190 are
not stitch bonded together. Instead the fibers are stitch
bonded to the fibers 192 of the lower layers as
represented by lines 196.
In FIG. 11, a portion of a composite reinforcement
layer is shown generally at 174. The composite
reinforcement layer includes an interior fabric layer
which is the same as the fabric layer 176 shown in FIG.
10. In addition, an exterior fabric layer 178 is provided
which is the same as the fabric layer as shown in FIG. 8.
This dual fabric layer composite reinforcement provides
added structural strength when desired.
The ability of a fabric reinforced wall to withstand
atypical loading such as is encountered during earthquakes
can be further enhanced by injecting a hardenable
material between the composite reinforcement layer and the
wall face after the resin in the composite reinforcement
layer is substantially cured. The hardenable material
preferably has low-shrink characteristics such that, upon
injection and hardening, the pressure between the
composite reinforcement layer and the wall face is
increased. Where this technique is used, it is
WO 95134724 PCTIU595106921
~~C.a~~ f _'a
preferable, but not essential, to place an inflatable
bladder between the composite reinforcement layer and the
wall to be used as a housing for the hardenable, low
shrink material. A more detailed discussion of this
5 method is disclosed in U.S. Patent No. 5,043,033 describe
above.
A .method is thus disclosed for increasing the
ductility and strength of a walls in situ without removing
the walls from service and without the need to provide
10 auxiliary support during the repair process.
Although the present invention has thus been
described in detail with regard to the preferred
embodiments and drawings thereof, it should be apparent to
those skilled in the art that various adaptations and
15 modifications of the present invention may be accomplished
without departing from the spirit and the scope of the
invention. Thus, by way of example and not of limitation,
conventional metal or high strength plastic fasteners may
be used to anchor a composite reinforcement layer to a
20 structural member of a wall to be reinforced.
Those skilled in the art will also understand that it
is generally preferable to reinforce the obverse face of
a wall where structurally feasible and economically
practicable. Accordingly, it is to be understood that the
detailed description and the accompanying drawings as set
forth hereinabove are not intended to limit the breadth of
the present invention, which should be inferred only from
the following claims and their appropriately construed
legal equivalents, rather than from the examples given.
