Note: Descriptions are shown in the official language in which they were submitted.
CA 02732690 2011-02-25
SUPPORTING REBAR WITH INTERCHANGEABLE CROWNS
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is related to the following commonly owned co-pending U.S.
Patent Application:
Provisional Application Serial No. 61/309,787, "System and Method of
Supporting Rebar with Interchangeable Crowns," filed March 2, 2010, and claims
the
benefit of its earlier filing date under 35 U.S.C. 119(e).
TECHNICAL FIELD
The present invention relates to reinforcing bars ("rebars") used in
construction, and more particularly to retaining a rebar, a wire mesh, an
electrical
conduit, plumbing or other elongated bar in a desired configuration during
construction.
BACKGROUND
Concrete is commonly used as a construction material because of its relatively
low cost. Concrete is very strong in compression, but weak in tension. To
increase
the tensile strength of concrete, steel reinforcement bars ("rebars") are
added. For
foundations, road work or other flat constructions, the rebar is often laid
out in a grid
pattern beneath the surface of the construction. To hold the rebar together in
a grid,
the bars are tied together where they intersect.
Various codes specify where the rebar must be placed. For example, the
American Concrete Institute (ACI) in Section 318 of their code specifies that
the
rebar in a slab-on-grade foundation must be placed at the midpoint depth of
the
foundation. Thus, for example, in a four inch foundation slab, the rebar grid
would
normally be placed at a depth of approximately two inches. Consequently, the
grid
must be elevated off the ground to the desired position before concrete is
poured. In
many cases, concrete laborers use stones, pieces of broken bricks or materials
to
elevate the grid. This can cause the grid to be uneven or sag when the
concrete is
poured.
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For concrete pillars and beams, the rebar is tied to a set of wooden frames
and
placed in a mold. The concrete is then poured into the mold to form the
pillar, beam
or other construction. However, this method suffers many disadvantages. First,
it is
difficult to align the rebar in parallel around the frames. Second, the frames
often
break or shift when the concrete is poured, causing the rebar to become
misaligned.
This reduces the tensile strength of the construction.
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BRIEF SUMMARY
In one embodiment of the present invention, a support structure for retaining
a
reinforcing bar comprises a reinforcing bar engaging portion, where the
reinforcing
bar engaging portion comprises a receptacle to receive the reinforcing bar.
The
receptacle comprises a channel sized to receive the reinforcing bar, where the
channel
comprises a first portion and a bar retaining portion defined by sidewalls
that extend
radially outward from a first end to a second end. The retaining features are
disposed
on the walls of the channel, where the sidewalls are configured to spread so
that the
reinforcing bar passes the retaining features and rests in the bar retaining
portion as
the reinforcing bar moves down the channel. Additionally, the support
structure
comprises a support portion supporting the reinforcing bar engaging portion,
where
the support portion comprises a plurality of legs which project outward from a
central
axis. In addition, the support structure comprises a base configured to
distribute
weight of the support structure.
In another embodiment of the present invention, a support structure for
retaining a wire mesh comprises a wire mesh engaging portion, where the wire
mesh
engaging portion comprises a receptacle to receive the wire mesh. The
receptacle
comprises a channel sized to receive the wire mesh, where the channel
comprises a
first portion and a bar retaining portion defined by sidewalls that extend
radially
outward from a first end to a second end. The retaining features are disposed
on the
walls of the channel, where the sidewalls are configured to spread so that the
wire
mesh passes the retaining features and rests in the bar retaining portion as
the wire
mesh moves down the channel. The support structure further comprises a support
portion supporting the wire mesh engaging portion, where the support portion
comprises a plurality of legs which project outward from a central axis. In
addition,
the support structure comprises a base configured to distribute weight of the
support
structure.
The foregoing has outlined rather generally the features and technical
advantages of one or more embodiments of the present invention in order that
the
detailed description of the present invention that follows may be better
understood.
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Additional features and advantages of the present invention will be described
hereinafter which may form the subject of the claims of the present invention.
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BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
A better understanding of the present invention can be obtained when the
following detailed description is considered in conjunction with the following
drawings, in which:
Figures IA and 113 illustrate a support structure for retaining a rebar in
accordance with an embodiment of the present invention;
Figure 2 illustrates a top view of the base illustrating the different
positioning
and sizes of the foot receptacles in accordance with an embodiment of the
present
invention;
Figure 3 illustrates two embodiments of the crowns with feet inserted in the
foot receptacles of the base in accordance with an embodiment of the present
invention;
Figure 4 illustrates a side view of one embodiment of the present invention of
a crown;
Figures 5A-5E illustrate various embodiments of the present invention of snap
fits;
Figures 6A-6D illustrate various embodiments of the present invention of a
foot engaging a foot receptacle;
Figure 7 illustrates a set of support structures supporting mats of bars in
accordance with an embodiment of the present invention;
Figure 8 illustrates additional views of a crown in accordance with an
embodiment of the present invention;
Figures 9A-9C illustrate representations of one embodiment of the present
invention of a portion of a support structure;
Figure 10 illustrates an additional view of the base in accordance with an
embodiment of the present invention;
Figure 11 is a flowchart of a method for laying out rebar in accordance with
an embodiment of the present invention; and
Figure 12 illustrates a rebar support structure in accordance with an
embodiment of the present invention.
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DETAILED DESCRIPTION
Embodiments described herein provide systems for retaining a rebar, a wire
mesh, an electrical conduit, plumbing or other elongated bar in a desired
configuration during construction. Embodiments described herein will be
described
primarily in the context of a rebar, but it should be understood that the
embodiments
are not limited to rebars and can be used to retain other types of bars.
Figures IA and 1B are diagrammatic representations of one embodiment of
the present invention of a support structure 100 for retaining a rebar.
Support
structure 100 can include a rebar engaging portion 102, a support portion 104
and a
base 106. Support portion 104 and rebar engaging portion 102 can be formed of
a
single piece of material or they can be separate components that are coupled
together
while base 106 is a separate base. For purposes of this application, rebar
engaging
portion 102 and support portion 104 are referred to as a "crown" 107.
Support structure 100 can be formed of a suitable material, such as resilient
plastic or other material, and can be manufactured to surpass requirements
from the
Uniform Building Code, International Building Code, American Concrete
Institute,
American Association of State Highway and Transportation Officials and
standard
practices as specified by the American Concrete Institute, the Concrete
Reinforcing
Steel Institute and other requirements. According to one embodiment, support
structures 100 can be manufactured to have a capacity exceeding expected
construction loads, which typically range between 250-300 pounds. Support
structures 100, according to one embodiment of the present invention, can have
a
critical load in axial compression of 320 pounds or more. According to one
embodiment, support structures 100 can have a critical load in axial
compression of
approximately 400 pounds. Other embodiments can have higher or lower critical
loads as needed or desired. In one embodiment, support structure 100 can be
configured so that it does not require ties or caps to retain the rebar.
Crown 107 can be used in a variety of applications for supporting the rebar in
cement, including, but not limited to, foundations and cement beams. Rebar
engaging portion 102 comprises one or more receptacles to receive the rebar.
In the
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case of Figure 1, engaging portion 102 includes paired bar receptacles 11 Oa
and 1 IOb,
bar receptacles 112a and 112b, bar receptacles 114a and I14b and bar
receptacles
115a and 115b to receive the rebar. While eight bar receptacles are shown for
the
purposes of illustration, engaging portion 102 can include any number of bar
receptacles that will fit to retain one or more pieces of rebar.
According to one embodiment, each set of paired receptacles can be sized to
fit different sizes of rebar. In other embodiments, each set of paired
receptacles can
be sized to fit the same size of rebar. The depth of bar receptacles 110, 112
and 114
can be offset from each other so that the bars supported by engaging portion
102 can
cross each other at the center of engaging portion 102. The bar receptacles of
engaging portion 102 can be positioned so that the bars cross at a 90 degree
angle or
other desired angle. The bar receptacles can be snap-fit receptacles that
allow a bar to
be fully inserted by a human while inhibiting removal of the bar. The snap fit
can
provide feedback to the user so that the user knows when the bar has been
sufficiently
inserted and can result from the spring action of the bar receptacles.
Support portion 104 provides supports such as a plurality of leaves or legs
116
which project outward from a central axis and support rebar engaging portion
102.
Support portion 104 can include any number of legs 116 or supports and the
legs can
have various configurations. Various embodiments of legs 116 are discussed
below.
Legs 116 can include feet 118 on which support portion 104 rests. According to
one
embodiment, each leg 116 can taper toward the respective foot 118 to leave
area 120
open. This can allow concrete to flow beneath the legs 116 and between the
feet 118.
Base 106 can be shaped to distribute weight. In the embodiment of Figure 1,
base 106 can be ring shaped, but in other embodiments, base 106 can include a
solid
disk, a rectangular shape or other shape. Base 106 includes foot receptacles
122 sized
and positioned to receive feet 118. Foot receptacles 122 can be sized to form
an
interference fit with feet 118 to inhibit removal of base 106. In other
embodiments,
foot receptacles 122 and feet 118 may include a snap on fitting or feature
that engages
to inhibit removal of base 106. The snap-fit can close due to the spring
action of foot
receptacles 122 and can provide tactile or other feedback so that a user knows
when a
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foot is properly engaged in foot receptacle 122. Foot receptacles 122 can be
shaped
so that there are no gaps between the walls of foot receptacles 122 and the
corresponding feet 118, thereby reducing the likelihood of trapped air
bubbles.
Additionally, base 106 can include foot receptacles 124. Foot receptacles 124
can be sized and positioned to receive the feet of a different sized crown
107. Thus, a
single base can be made for use with interchangeable crowns 107.
Having a separate crown 107 and base 106 provides many advantages over
existing systems. Crown 107 can be used in a number of applications with or
without
base 106 as needed or desired. Using crown 107 without base 106 provides
to advantages over prior art rebar chairs described in United States Patent
No. 6,282,860
(the "'860 Patent"). When the rebar chairs of the `860 Patent are used in the
construction of concrete beams, the bases of the chairs will typically show
through
the side of the beam as large unsightly rings. This requires the beam to be
painted or
have another coating applied to hide the rings. Crowns 107 of the present
disclosure,
on the other hand, can be used without bases 106 and therefore will not leave
exposed
rings. In this case, if a portion of a crown 107 shows, it is only the bottom
of the feet
118, which is a very small area. The same type of crown 107 can be used with
base
106 in applications that require more stability or weight distribution, such
as building
over soft earth or sand. Thus, the same model of crown has different modes of
operation.
Figure 2 is a diagrammatic representation of a top view of base 106
illustrating the different positioning and sizes of foot receptacles 122 and
124 in
accordance with an embodiment of the present invention. While eight foot
receptacles 122 and 124 are illustrated, base 106 can include any number of
receptacles. Additionally, while different receptacles are illustrated to
accommodate
different size crowns, a single type of foot receptacle can be used if the
different sized
crowns have the same leg configuration.
Figure 3 is a diagrammatic representation of two embodiments of crowns 107
with feet 118 inserted in foot receptacles 122 or 124 of base 106 in
accordance with
an embodiment of the present invention.
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Figure 4 is a diagrammatic representation of a side view of one embodiment
of the present invention of crown 107. Receptacle I10a includes a channel 130
open
to the top of crown 107 and sized to receive the rebar. Channel 130 can have a
first
portion 138 and a bar retaining portion 139 defined by sidewalls 132 that
extend
radially outward from a first end (e.g., more proximate to the center of crown
107) to
a second end (e.g., the edge of crown 107). The base of channel 130 can be
flat,
curved or have another shape, but a curved shape increases the lateral
elasticity of
receptacle 11 Oa. Sidewalls 132 can angle so that the receptacle 11 Oa is
wider at the
opening than near the base of channel 130. Retaining features 137 can be
disposed on
the walls of channel 130. In one embodiment, retaining features 137 can be
bumps or
other features so that the width of the opening to bar retaining area 139 is
smaller than
the width of bar retaining area 139 or the rebar. In various embodiments,
retaining
features 137 can be formed based on the shape of sidewalls 132, can be
projections
that project inward from sidewall 132 or can be another feature that allows
the rebar
to enter rebar retaining area 139 due to the pressure of the rebar, but
inhibit the rebar
from leaving bar retaining area 139.
In operation, the rebar can be inserted in a first portion 138 of channel 130.
As the rebar moves down channel 130, sidewalls 132 can spread slightly so that
the
rebar can pass bumps 137 and rest in bar retaining area 139 on base 141.
According
to one embodiment, bumps 137 snap over the bar to inhibit the bar from coming
out
of channel 130. The material, thickness or other properties of sidewalls 132
can be
selected so that the rebar can be inserted manually.
Figure 4 also illustrates another embodiment of a receptacle 115b having
channel 140 defined by sidewalls 142 and having retaining features 147. Rebar
can
be snapped into channel 140 and can rest in portion 143. For example, the
rebar can
rest on shoulders 144. Channel 140 can be open to an area 145 that has a
curved
shape to allow channel 140 greater lateral elasticity. This can allow channel
140 to
better accommodate a range of rebar sizes.
The receptacles can be joined to each other by arms 143. According to one
embodiment, the sidewalls of the receptacles and arms can be formed by a
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continuous, unitary shaped rib of material that projects radially outward from
a first
edge near the center of crown 107 to an outer edge. The rib can be laid out in
an
annular shape with an opening or gap between paired receptacles. Thus, each
receptacle, according to one embodiment, does not extend to the base of the
paired
receptacle (e.g., the base 141 of receptacle 110a does not extend across
engaging
portion 102 to the base of receptacle 11 Ob). Instead, there may be a gap
between the
paired receptacles at the center of crown 107.
Figures 5A-5E illustrate various embodiments of the present invention of snap
fits. Figures 5A-5C include various embodiments of retaining features 137
including
a tapered flange (Figure 5A), rounded flange (Figure 5B), a set of teeth
(Figure 5C)
and a set of bumps (Figure 5D). It should be noted that the embodiments of
Figures
5A-5D are provided by way example. While each embodiment of Figures 5A-5D
includes a taper or curve to ease insertion of the rebar, other embodiments of
retaining features 137 can have other configurations. Retaining features may
be
disposed on both sidewalls or only one sidewall and multiple types of
retaining
features can be used. In one embodiment, the snap fit provided by a bar
receptacle
can be based, in part, on deformation of retaining features 137. In Figure 5E,
the
rebar can enter the receptacle in a first direction and snap in a second
direction.
Figures 6A-6D are diagrammatic representations of various embodiments of
the present invention of a foot 118 engaging a foot receptacle 122. The
retaining
feature to retain foot 118 in receptacle 122 can be configured so that foot
118 cannot
be removed without damaging receptacle 122 or foot 118 or can be configured so
that
foot 118 can be removed without causing damage if a threshold amount of force
is
applied. According to one embodiment, receptacle 122 can have sidewalls 148
that
are sized to flex outward as foot 118 is inserted. Complementary engaging
features
on sidewalls 148 and foot 118 can engage to hold foot 118 in place. In Figure
6A,
foot 118 includes an indent 150 that engages a detent 152 on wall 148 of
receptacle
122. The resiliency of walls 148 can hold detent 152 in indent 148 so that a
threshold
amount of force is required to disengage foot 118 from receptacle 122. In
Figure 6B,
flanges 154 on walls 148 move over shoulders 156 on foot 118 to hold foot 118
in
receptacle 122. In Figure 6C, a tab 153 on foot 118 is received in a
complementary
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receiver in sidewall 148. In Figure 6D, bumps 157 fit over a portion of foot
118 to
inhibit removal of foot 118. The examples of Figures 6A-6D are provided by way
of
example and other engaging features can be used. In other embodiments, foot
118
and sidewalls 148 can form an interference fit based on sizing. The foot
receptacles
can be snap-fit receptacles that provide feedback to the user so that the user
knows
when a foot has been fully inserted.
Figure 7 is a diagrammatic representation of a set of support structures 100
supporting layers (referred to as "mats") of bars in accordance with an
embodiment of
the present invention. A first set of support structures 100 can support a
first mat 160
while a second set of support structures 100 can support a second mat 162 at a
different height. While both mat 160 and mat 162 can be grids of rebar, in
other
embodiments, mat 160 can be a grid of rebar, while mat 162 includes plumbing,
electrical conduit or other material. In some cases, a layer may include
multiple types
of rods (e.g., rebar and electrical conduit, plumbing and electrical conduit,
etc.). Each
support structure can use the same type of base 106, but use different crowns
for
different sizes of rebar, plumbing or other material. Concrete can be poured
around
the layers to create a construction.
Figure 8 provides additional views of a crown 107 in accordance with an
embodiment of the present invention.
Figures 9A-9C are diagrammatic representations of one embodiment of the
present invention of a portion of support structure 104. Figure 9A illustrates
that legs
116 can taper upwards to create open area 120 between feet 118. In other
embodiments, legs 116 can curve upwards (Figure 9B) or have another profile to
allow cement to fill between legs 116. In other embodiments, legs 116 do not
extend
inward to the center axis but only extend downward from the engaging portion
102
(Figure 9C). Additionally, Figure 9A illustrates that leg 116 can have holes
122
having a desired shape. The holes can be circular (Figure 9A), diamond shaped
(Figure 9B), triangular (Figure 9C), elliptical, rectangular, square or
otherwise
shaped.
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Figure 10 is a diagrammatic representation of another view of a base 106 in
accordance with an embodiment of the present invention.
Figure 11 is a flowchart of a method 1100 for laying out the rebar according
to an embodiment of the present invention. A user can select a crown based on
the
size(s) of rebar being used, application, ordinances, construction practices
or other
factors (step 200). The user can also select the mode in which the crown will
be used
based on the application (step 202). This can include, for example, selecting
whether
to use the crown with or without the base. If the crown is being used in a
wall or
beam, the user may want to forego the base, whereas if the crown is being used
in a
foundation or slab, the user may want to use the base for added stability or
weight
distribution. The crowns with or without the bases can spaced as needed or
desired
(step 204). In some cases, the spacing of crowns is based on ordinances,
standards or
industry practices as to how often the rebar needs to be tied together. The
following
Table 1 provides example spacing for crowns. However, other spacing can be
used as
needed or desired:
Rebar Size Max Spacing
5/8 inch or #5 4 feet center-to-center
1 /2 inch or #4 3 feet center-to-center
3/8 inch or #3 2 feet center-to-center
'/4 inch or #2 2 feet center-to-center
wire mesh 4 feet center-to-center
Rebar running in a first direction can be snapped into the crowns (step 206).
If rebar running in another direction is to be used, the rebar can be snapped
in the
crowns in a second direction (step 208). The rebar running in the first
direction may
be at any angle as allowed by the crown up to 90 degrees from the rebar
running in
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the second direction. If different sizes of rebar are used, the larger rebar
is snapped in
over the smaller rebar. However, in other embodiments, the smaller rebar can
be
snapped over the larger rebar. The steps of Figure 11 can be repeated as
needed or
desired.
Figure 12 illustrates another embodiment of the present invention of a rebar
support structure 300 that includes a rebar engaging portion 302, a support
portion
304 and a base 306. As described above, base 306 can be a detachable base so
that
base 306 can be used with various crowns 307. In the embodiment of Figure 12,
crown 307 includes a rebar receptacle 310 in which the rebar rests. The rebar
is held
in place by a cap 312. In other embodiments, removable base 306 can be used
with
rebar chairs in which the rebar is tied onto the chair.
While embodiments above have been discussed in the context of rebar,
embodiments of the present application can be used with graphite tubing, glass
tubing, plumbing, conduit, wire mesh, or any other elongated rod.
As used herein, the terms "comprises," "comprising," "includes," "including,"
"has," "having" or any other variation thereof, are intended to cover a non-
exclusive
inclusion. For example, a process, product, article, or apparatus that
comprises a list
of elements is not necessarily limited to only those elements but may include
other
elements not expressly listed or inherent to such process, article, or
apparatus.
Further, unless expressly stated to the contrary, "or" refers to an inclusive
or and not
to an exclusive or. For example, a condition A or B is satisfied by any one of
the
following: A is true (or present) and B is false (or not present), A is false
(or not
present) and B is true (or present), and both A and B are true (or present).
Additionally, any examples or illustrations given herein are not to be
regarded
in any way as restrictions on, limits to, or express definitions of, any term
or terms
with which they are utilized. Instead these examples or illustrations are to
be
regarded as being described with respect to one particular embodiment and as
illustrative only. Those of ordinary skill in the art will appreciate that any
term or
terms with which these examples or illustrations are utilized encompass other
embodiments as well as implementations and adaptations thereof which may or
may
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not be given therewith or elsewhere in the specification and all such
embodiments are
intended to be included within the scope of that term or terms. Language
designating
such non-limiting examples and illustrations includes, but is not limited to:
"for
example," "for instance," "e.g.," "in one embodiment," and the like.
Further modifications and alternative embodiments of various aspects of the
disclosure will be apparent to those skilled in the art in view of this
description.
Accordingly, this description is to be construed as illustrative only and is
for the
purpose of teaching those skilled in the art the general manner of carrying
out the
disclosure. It is to be understood that the forms of the disclosure shown and
described herein are to be taken as the presently preferred embodiments.
Elements
and materials may be substituted for those illustrated and described herein,
parts and
processes may be reversed, and certain features of the disclosure may be
utilized
independently, all as would be apparent to one skilled in the art after having
the
benefit of this description of the disclosure. Any dimensions provided are
provided
by way of example only and not limitation. Changes may be made in the elements
described herein without departing from the spirit and scope of the
disclosure.
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