Note: Descriptions are shown in the official language in which they were submitted.
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REBAR SL1PPOR'p CFIAIR
Background of the Invention
Field of the Invention
The present invention relates generally to chairs and spacers that are used
in construction activities for the support of steel reinforcement members
within concrete
structures, and in particular to a stackable chair that reliably retains
reinforcement bars,
post-tension cables, rods, and the Like
Description of the Related Art
Chairs or spacers are commonly used in the construction industry for the
support and positioning of steel reinforcement members such as post-tension
cables
and/or reinforcement bars("rebar") a proper distance above a surface. The
rebar is
usually a~~anged in rows or grids within a..n area into which concrete is to
be poured, and
are held loosely in place while concrete is placed around them. In normal use,
a
receiving area formed on the chair will contact and support the rebar while
the base of
the chair rests on a deck or on a grade,
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Proper spacing and arrangement of steel reinforcement members in
concrete slabs according to known engineering and architectural specifications
impacts
the structural strength and integrity of the concrete structure. Such steel
reinforcement
requires sufficient cover to avoid exposing the steel to the effects of
moisture-
penetrating corrosion. Once the steel is exposed to the effects of chemical-
laden
moisture, corrosion starts taking effect.
Known prior art chairs have desirable features which provide the proper
support of rebar or post-tension cables safely within a concrete stricture.
Some chairs
also have additional .desirable features. For example, U.S. Patent No.
5,729,949 to
IO Hartzheim discloses a readily stackable chair with a hollow-conical body
that minimizes
the amount of shipping and storage space required. .These chairs have support
legs with
apertures between them to allow concrete to flow into the hollow interior of
the chair.
A worker can carry many chairs at one time and place numerous chairs at a
construction
site without repeated trips to a storage area.
U.S. Patent No. 6,089,522 to Harlem et al. discloses a stackable high
chair having a lower base portion, an upper connecting portion and an upper
support
surface. The upper support surface includes bisecting cross members which join
opposing corners of the upper support surface. Inclined ramps extend upwardly
from
the support surface and serve to position the rebar along the upper surface.
The upper
support surface also includes a plurality of holes which allows a head piece
to be
mounted to the chair, thereby allowing the height of the chair to be readily
adjusted.
While the prior ar~~ chairs described above may be useful for their
respective, particular obj ectives, a need exists for a stackable chair that
is tall enough to
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support rebar a significant distance above a surface, yet has a simple and
stxong
construction.
Summar~of the Inven.~ion
Accordingly, one objective of the present invention is to provide a chair
with a simple yet strong design that is tall enough to support rebar a
significant distance
above a surface. It is also an objective to provide a tall chair that is Iight
in weight yet
able to securely support rebar. Yet another objective of the invention is to
provide a tall
rebar support chair with a wide base that allows the chair to stand securely.
It is a
further obj ective of the present invention to provide a rebar support chair
that can be
stacked within another chair to provide a more efficient method for packaging,
storage,
and shipment. It is also an objective to provide a plastic.chair made of
durable, non-
corrosive materials that is easy to manufacture and easy to use.
Briefly stated, these obj ectives are accomplished by a generally funnal-
shaped support chair having a hollow body with an inner surface, an outer
surface, a
receiving area, and a base. The base defines a lower opening and is adapted to
rest on a
planar support surface. The receiving area is adapted to receive and support
the rebar.
The lower opening of the chair is larger than the receiving area, and the
inner and outer
surfaces are substantially complementary to each other to allow a plurality of
chairs to
be stacked within each other for storage and shipment. Additionally, the
stacking
feature allows a worker to carry a stack of chairs at the jab site as he
places them at
desired locations.
In one embodiment of the invention, the receiving area includes a first
and a second pair of curved notches, with the second pair being oriented
ninety decrees
from the first pair. The first pair of notches has a first depth, and the
second pair of
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notches has a second depth. In this embodiment, the first pair is deeper than
the second
pair; and the chair is thus able to support rebar at different heights acid in
perpendicular
relationships to one another. The receiving area may optionally include a
plurality of
bridges. A bridge is a band of material that spans the distance within the
body of the
chair between each of the pairs of notches. The bridges can assist to further
increase the
supporting strength of the chair, and can connect the medial, lowest:
portions, or troughs,
of the notches.
In accordance with one aspect of the invention, the base includes a
plurality of support legs which define a plurality of apertures, and the
apertures allow
I O poured concrete to pass fluidly through the chair. The apertures are
preferably arch-
shaped, and the support legs preferably have a thickened band of material
around the
apertures, such that the strength of the chair is reinforced by these
thickened areas to
allow the support legs to be longer yet retain their strength. In one
embodiment, the
base has four support legs, with two of the support legs further including
foot members
extending horizontally outwardly therefrom, the other two support Iegs lacking
a foot
member. In this embodiment, the foot members extend from support legs which
are
diametrically opposed from one another.
In another embodiment of the invention, the base includes upper and
Iower support Iegs. The lower support legs are the primary set of legs and are
larger
than the upper support legs. The receiving area is supported by both the upper
and
lower support legs; with the upper legs extending downwardly from the
receiving area,
and the Iower support Iegs extending downwardly nom the upper support legs. W
one
embodiment, the upper legs can include upwardly extending ribs on their outer
surface.
These ribs extend along each of the upper support legs between the junction of
the lower
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and upper legs. In this embodiment, the chair can be made to be significantly
taller than
other chairs of the prior art, and also be light in weight yet strong enough
to support
rebar securely, and without collapsing under the weight of the rebar.
Preferably the
chair is advantageously manufactured as a single piece of material, such that
the chair
can have the height and strength of a chair having a head piece seated on top
of a base
chair, yet be a single, tall chair with two sets of support Iegs.
In accordance with another aspect of the invention, the body of the chair
has multiple substantially straight sides and a substantially square cross-
section having
rounded comers, with an inner surface that is complementary to the outer
surface to
allow a plurality of chairs to be stacked together, one inside the other, for
storage and
shipment. The chair may also have an elliptical; oval or hybrid cross-section.
The chair
preferably has a wide base which is adapted to rest on a flat support surface.
The Iower
opening is defined by the base and is preferably larger than the upper
receiving area; and
the inner and outer surfaces are preferably substantially complementary to
each other.
In accordance with anothex aspect of the invention, the receiving area and
the base are integrally formed together from a durable, non-corrosive
polymeric
material. The chairs are easy to manufacture in this fashion, and packaging
and storage
of the chairs can be done quickly and easily because the chairs axe also
stackable. These
and other aspects of the present invention will be more fully appreciated with
respect to
the following drawings and detailed description.
Rr:ef ~escrapt:on of the In~-a~ings
FIG. I is a perspective view of one embodiment of the chair of the
present invention;
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FIG. 2 is a perspective view of the chair of FIG. 1 inwhich rebar has
been placed in the receiving area;
FIG. 3 is a perspective view of another embodiment of the chair of the
present invention having two sets of support legs;
FIG. 4 is a perspective view of a plurality of chairs of Fig. 1 stacked
within one another in accordance with one aspect of the invention; and
FIG. 5 is a perspective view of a plurality of chairs of FIG. 3 arranged in
a stack.
Detailed Description of the Invention
Referring now to FIG. 1, a perspective view is shown of one embodiment
of the chair 8 of the present invention having a hollow body 10 including a
base 12, a
receiving area 14, an inner surface 16, an outer surface 18, and ribs 20
formed on the
outer surface for a purpose described below. The base IZ defines a Lower
opening 22
and is adapted to rest on a planar support surface. The receiving area I4 has
a plurality
of generally rounded notches 24, with elevated notch junctions 26 between
adjacent
notches. The lower base 12 has a plurality of separate support legs 32
extending
downwardly from the receiving area.l4. Foot members 34 extend radially outward
from
two opposing support legs 32. Adjacent support legs 32 define holes or
apertures 36,
which allow poured concrete to fluidly pass through the chair 8. The legs 32
have a
thickened band of material 40 around each aperture 36.
The Chalr of FIG. 1 is preferably ger~era.lly sq~aa.re iin cross-section havin
g
rounded corners and is constructed of a single piece of resilient polymeric
material.
However, alternative embodiments of the chair may have a polygonal,
elliptical, oval or
hybrid cross-section. The receiving area 14 is adapted to receive and support
concrete
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reinforcement members, ox sebar. a The inner surface 16 is complementary to
the outer
surface 18, and the body 10 has multiple straight sides and is generally
tapered, with the
lower opening 22 being larger than the receiving area 14, thereby allowing
multiple
chairs to be stacked within one another for storage and shipment. The tapered
shape of
the chair also requires that the upper portion of the body 10, including the
receiving area
14, is generally relatively narrow as compared to the lower portion, which
includes the
wider base I2. Ribs 20 function to space stacked chairs and facilitate their
separation.
The apertures 36 between the support legs 32 are preferably arch-shaped
and allow fluid concrete to pass through the body I O beneath the level of the
receiving
area 14. The large openings provided by the apertures 36 maximize the free
flow of
concrete into and around chair 8. The support legs 32 preferably have a
thickened band
of material 40 around the apertures 36, such that the strength of the chair is
reinforced
by these thickened areas 40 to allow the support legs 32 to be longer yet
retain their
strength. As shown, the base 12 has four support legs 32, with two of the
support legs
further including foot members 34 extending horizontally outwardly therefrom,
the
other two support legs lacking a foot member. In FIG. 1, the foot members 34
extend
from support legs 32 which are diametrically opposed from one another.
FIG. 2 shows reinforcement members 38 and 39 being supported by the
chair 8 of FIG. 1. Reinforcement members 38 and 39 intersect with one another
within
the receiving area 14. The receiving area 14 includes a first and a second
pair of curved
notches, 24a and 24 b, respectively, with the second pair 24b being oriented
ninety
degrees from the first pair 24a. The notches 24a; 24b comprise curved bearing
surfaces
extending inwardly from outer surface 18. The first pair 24a are deep notches
which
receive rehar member 3 8, and the second pair of notches 24b are shallow
notches which
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receive rebar member 39, such that rebar member 39 is situated above and
perpendicular
to member 38 within the receiving area I4. The chair 8 is thus able to support
rebar
members 38 and 39 both at different heights and in perpendicular relationships
to one
another.
As a non-limiting example of how the reinforcement members 38 and 39
are placed within the chair 8, reinforcement member 38 is initially positioned
over the
receiving area I4 .and then lowered into the deep notches 24a. Reinforcement
member
39 is then lowered into the shallow_pair of notches 24b. Notch pairs 24a are
preferably
deep enough to allow reinforcement member 38 to sit within the receiving area
14 while
also allowing member 39 to sit completely within the shallow notch pairs 24b
without
interference from member 38.
FIG. 2 further illustrates the tapered shape of the chair 8. The upper
portion of body I 0 is narrow at the receiving area I4. The body I0 gradually
widens
from the notch junctions 26 down to the ends of the support legs 32. The lower
opening
22 is therefore much larger in circumference than the receiving area 14. Also,
each
support leg 32 proceeds downwardly in a straight line from a junction 26.
Preferably,
two of the support legs 32 have a foot member 34 extending horizontally
outwardly
therefrom, adding further support to the base such that the base is well
adapted to
support the weight of the chair 8 as well as the reinforcement members 38, 39.
FIG. 3 illustrates another embodiment of the chair 108 in which the base
112 inch~des both lower 132 and upper I 33 support legs. The lower support
leas 132
are the primary- set of legs and are larger and longer than the upper support
leas IJ3.
The receiving area l I4 is supported by both the upper and lower support legs
132, 133,
with the upper leas 13 3 extending downwardly from the receiving area 114 and
defining
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upper apertures 137, and the Iou~e~r support legs I32 extending downwardly
from the
upper support legs 133 and defining Iower apertures I36. A Iedge 142 defines
the
junction between the upper 133 and lower 132 Iegs, and can be seen extending
around
the circumference of the body I 10.
S As shown in FIG. 3, the base 122 has four lower support Iegs 132, with
two of the Iower support legs I32 further including foot members 134 extending
horizontally outwardly therefrom, the other two lower support legs lacking a
foot
member. The foot members I34 extend from diametrically opposed lower support
legs
132. Upwardly extending ribs 12G are disposed ors oater surface 118 and act as
spacers
to.facilitate separation of stacked chairs, as described above with respect to
ribs 20 of
FIGS. I and 2.
The lower and upper apertures 136, 137 between the lower and upper
support legs I32, 133, respectively,.are preferably arch-shaped and allow
fluid concrete
to pass through the body I 10 beneath the level of the receiving area 114. The
large
openings provided by the apertures 136, 137 maximize the free flow of concrete
into
and around chair 108. The lower support legs 132 preferably have a thickened
band of
matezial 140 around the lower apertures 136, such that the strength of the
chair is
reinforced by these thickened areas 140 to allow the Iower support legs 132 to
be longer
yet retain their strength.
The receiving area 114 shown in FIG. 3, similar to the receiving area I4
in FIGS. I and 2, is adapted to receive and support concrete reinforcement
members, or
rebar. The inner surface 116 is complementary to the outer surface 118, and
the body
1 IO has multiple straight sides and is generally tapered, with the lower
opening 12?
being larger than the receiving area I 14, thereby allowing multiple chairs to
be stacked
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within one another for storage and shipment. Advantageously, the stackable
chairs 108
facilitate handling on a job site, whereby workers rnay carry a stack of
chairs 108 in one
hand while placing individual chairs from the stack at desired locations at
the job site.
The receiving area 1 I4 of FIG. 3 further includes a plurality of bridges
128. A bridge junction 130 is farmed where two bridges I28 meet in the center
of the
receiving area 114. The bridges 128, which are shown here but are an optional
element
of the chair I08, connect the medial, lowest portions, or troughs, of the
notches I24, and
span the distance within the body 110 of the chair between the notches I24.
The
bridges 128 assist to further increase the supporting strength of the chair 8.
The bridges
128, which are optional, serve to support the rebar members 138 and 139 as
they
traverse the body I 10 of the chair, and add strength and support to the
structure.
Apertures are shown in FIGS. I through 3 as being generally arch-
shaped, curved at the apex. One of skill in the art will recognize, however,
that a variety
of shapes, sizes, and numbers of apertures can be used. Support lf;gs are
generally of
sufficient width and strength to support a substantial Load, such as the force
of the
reinforcement members as well as the force applied by construction workers who
may
step or walk on the reinforcement members during the construction process. The
thickened band of material around the apertures also adds strength to the
structure, so
that the chair does not collapse under such weight. Each foot member allows
the base to
rest on a flat, planar support surface, including loose or pliant surfaces
such as dirt,
sand, or the like.
As illustrated in FIG. 4, a plurality of chairs 8a and 8b can be stacked
together, one inside the other, for packaging, storage and shipment. The
combination of
the tapered, Generally funnel-Iike shape of chairs 8a and 8b, along with
th°
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s
complementary surfaces, allows the upper receiving area of chair 8a to be
inserted
within the lower opening 22 of chair 8b, such that the outer surface I8a of
the first chair
slidably engages the inner surface of the second chair. The distance that a
first chair is
able to fit inside a second chair is dependant upon the degree of slope
assurr~ed by the
surfaces 16 and 18 as the body 10 progresses from the receiving area 14 to the
Iower
opening 22. That is, the smaller the receiving area is relative to the lower
opening 22,
the greater the slope will be of the surfaces 16 and 18. Preferably, this
slope is
sufficient to allow a substantial portion of the first chair to fit within the
second chair,
such that a great number of chairs can be stacked in a minimal amount of space
without
the stack becoming too tall or burdensome. As noted above, ribs 20 space
stacked
chairs and facilitate their separation.
As shown in FIG. 4, the chairs can be stacked with the foot members of
one chair on opposite support legs as the foot members of the preceding chair,
or
alternatively the foot members can be on the same corresponding support leg,
such that
a user can recognize a specific corner of the chair. It will be apparent that
the stacking
capability allows a workman to carry a stack of chairs with one hand as he
places chairs
at the j ob site.
The chair of the present invention can be made significantly taller than.
most chairs of the prior art, and also is Iight in weight yet strong enough to
support rebar
securely, without collapsing under the weight of the rebar. Preferably the
chair is
advantageously manufactured as a single piece of material; and is constructed
from a
resilient polymeric material and, more specifically; is constructed of a
plastic or resin
material. In this manner, the chair can have the height and strength of a char
with a
head piece seated on top of a base chair; yet be a single; tall chair with two
sets of
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~ , _ ,
support legs. Further, the chair is most preferably made of polypropylene and
is one-
piece injection molded. One of ordinary shill in the art will recognize that
other
materials exhibiting 'similar characteristics of being lightweight, strong and
resilient can
be used, such as polyethylene, a combination of polypropylene and
:polyethylene, and
other known materials.
The present invention has been disclosed in detail in connection with the
preferred embodiments. While there are many minor rriodincations that can be
made
without departing from the scope of the present invention, the present
invention is
defined by the claims that follow.
Fga~ 1'~ Or 1
