Note: Descriptions are shown in the official language in which they were submitted.
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SLOTTED INSERT WITH CAPTURED NUT ANCHOR
TECHNICAL FIELD
[0001] The present disclosure relates to concrete forming systems, and more
particularly to slotted inserts used to provide cast concrete elements with
adjustable attachment points for wall panels, architectural panels, structural
framing, decking, and other precast or premanufactured structural components.
The slotted insert is embedded within a precast or site-cast concrete element,
with the captured nut providing an adjustable, threaded-bolt-type connection
for
adjoining precast or premanufactured structural components.
BACKGROUND
[0002] Slotted inserts are used in concrete construction, most typically in
precast construction, to provide adjustable anchoring or connection points
amongst precast and premanufactured structural components or between site-
cast foundations or walls and such structural components. Such inserts
typically
have a metal body defining both a longitudinally elongated slot and a
plurality
of transversely projecting legs, such as in the P30 Corewalle Nut Type Slotted
Insert (manufactured by Dayton Superior Corporation of Miamisburg, Ohio,
USA). A metal nut is captured behind the elongated slot and within a housing
defining elongated channel, with the captured nut being slidably positionable
along the length of the slot and channel to provide a longitudinally-
adjustable
connection. The cap and elongated slot may face horizontally and extend
vertically, e.g., be embedded within the face of a wall to provide a
vertically
adjustable connection point to a precast panel, or face vertically and run
horizontally, e.g., be embedded within a floor to provide a horizontally
adjustable connection point to a precast panel, however it will be appreciated
that the insert may be molded in and/or ultimately positioned in any
orientation,
without limitation, as required by the intended connection. The insert may be
attached to a concrete form so that the elongated slot is positioned against
the
inner face of the forming surface, or may be emplaced within a casting bed,
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with the cap and elongated slot facing upward and positioned proximate the
free
surface of the concrete, via attachment to a support member or even manual
setting within the wet concrete. The captured nut is frequently protected from
exposure to poured concrete by a removable cap positioned within the slot or
could alternately be protected by a means for forming a seal against the inner
face of the forming surface. Rebar is frequently clipped or tied to the
transversely projecting legs of the steel body, between the legs and the inner
face of the forming surface, to help to anchor the insert and resist pull-out
from
the surrounding concrete.
[0003] Wet concrete is poured and cured within an assembled formwork
around the attached insert. The formwork is subsequently stripped from the
formed concrete and embedded insert, with the elongated slot of the insert
ending up essentially flush with the surface of the formed concrete element.
The removable cap, if present, is removed to expose the elongated slot and the
captured nut, which remains longitudinally adjustable within the elongated
slot
but captured within the insert and the surrounding concrete. Precast or
premanufactured structural components such as wall panels, structural framing,
decking, and the like may be connected to the nut, insert, and surrounding
concrete by a threaded bolt or by a threaded-bolt-type connection such as a
threaded strap anchor. The resulting connection is both adjustable, to
accommodate variation in the dimensions of other components and the positions
of their connection points, and ductile, for use as a structural connection in
seismically active regions.
SUMMARY
[0004] The applicants have devised an improved slotted insert which
functions similarly to known slotted inserts, but does not require a metal
body
like that used in existing inserts. Instead, the slotted insert uses a multi-
part,
non-metallic void former housing a metal nut. The void former defines an
elongated slot with a first transverse width and a recessed, elongated channel
with a second, substantially greater transverse width. In use, the metal nut,
also
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having a transverse width substantially greater than the first transverse
width,
bears against concrete surrounding the void former rather than against a metal
body member. Consequently, the void former or insert body may be
manufactured entirely from molded plastics or other non-metallic materials.
Thus construction reduces the weight of the resultant insert, the cost of
manufacturing the insert, and the susceptibility of the insert to galvanic or
oxidative corrosion.
[0005] In a first aspect, a slotted insert comprises a non-metallic void
former
including a neck portion defining a longitudinally elongated slot, the neck
portion having a first transverse width, and a channel portion defining a
longitudinally elongated channel, the channel having a second transverse width
substantially greater than the first transverse width. The insert further
comprises a metal nut, captured within the channel, having an aperture and a
third transverse width substantially greater than the first transverse width.
The
longitudinally elongated slot and longitudinally elongated channel are
interconnected and mutually aligned such that the longitudinal axis of the
slot
and the longitudinal axis of the channel are parallel to each other, with the
aperture of the captured metal nut accessible through the slot.
[0006] In a second aspect, a formwork construction comprises an insert
including a non-metallic neck portion defining a longitudinally elongated
slot,
the neck portion having a first transverse width, a non-metallic channel
portion
defining a longitudinally elongated channel, the channel having a second
transverse width substantially greater than the first transverse width, a
metal nut
captured within the channel, the metal nut having an aperture and a third
transverse width substantially greater than the first transverse width, and a
removable cap portion configured to seal the longitudinally elongated slot
opposite the longitudinally elongated channel. The longitudinally elongated
slot
and longitudinally elongated channel are interconnected and mutually aligned
such that the longitudinal axis of the slot and the longitudinal axis of the
channel are parallel to each other, with the aperture of the captured metal
nut
accessible through the slot upon removal of the removable cap portion. The
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formwork further comprises a pair of metal reinforcing bars, bracketing the
void
former proximate the longitudinally elongated channel and extending parallel
to
the longitudinal axis of the channel. The insert is preferably affixed to the
metal
reinforcing bars via a plurality of clips projecting outwardly from the void
former channel portion.
[0007] In a third aspect, a formwork construction comprises a an insert
including a non-metallic neck portion defining a longitudinally elongated
slot,
the neck portion having a first transverse width, a non-metallic channel
portion
defining a longitudinally elongated channel, the channel having a second
transverse width substantially greater than the first transverse width, and a
metal
nut, captured within the channel, having an aperture and a third transverse
width
substantially greater than the first transverse width. The longitudinally
elongated slot and longitudinally elongated channel are interconnected and
mutually aligned such that the longitudinal axis of the slot and the
longitudinal
axis of the slot are parallel to each other, with the aperture of the captured
metal
nut accessible through the slot. The formwork further comprises a support
member, which may be a concrete form, wherein the neck portion is affixed to
an inner surface of support member via a plurality of fasteners inserted
through
a projecting tab or flange and into the inner surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of an embodiment of the void former.
[0009] FIG. 2 is an exploded perspective of the embodiment of FIG. 1 which
further illustrates the longitudinally elongated slot, longitudinally
elongated
channel, and captured metal nut.
[0010] FIG. 3 is a perspective view of a formwork assembly including metal
reinforcing bars affixed to the void former.
[0011] FIG. 4 is a perspective view of a formwork assembly including a void
former affixed to the inner surface of a support member.
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DETAILED DESCRIPTION
[0012] As shown in FIGS. 1 and 2, an insert 100 comprises a non-metallic
void former 110 including a neck portion 120 defining a longitudinally
elongated slot 130 and a channel portion 140 defining a longitudinally
elongated channel 150. The insert 110 also includes a metal nut 160 captured
within the channel 150. The channel 150 is substantially wider than the neck
portion 120, with "substantially" meaning for the purposes of this application
an
average, along the respective longitudinally elongated structures, of 1/4 inch
wider or more on each side, so as to permit the metal nut 160 to bear against
concrete surrounding the neck portion 120 of the void former 110. As shown
specifically in FIG. 2, the neck portion 120 may have a first transverse width
122, the defined channel 150 a second transverse width 152 substantially
greater
than the first transverse width 122, and the metal nut 160 a third transverse
width 162 substantially greater than the first transverse width 122. The third
transverse width 162 is preferably, but not necessarily, essentially equal to
the
second transverse width 152. The longitudinally elongated slot 130 and
longitudinally elongated channel 150 (i.e., the voids, not the void-forming
structures) are interconnected and mutually aligned such that the longitudinal
axis of the slot and the longitudinal axis of the channel are parallel to each
other.
[0013] The neck portion 120 and the channel portion 140 are preferably
separate portions of the insert 100 so that different neck portions 120 having
different depths 124 may be affixed to the same channel portion 140 in order
to
provide an adjustable, threaded-bolt-type connection 164 at different depths
from the surface of the concrete "S" (indicated in Fig. 3). The portions 120,
140
may be releaseably interlocking with each other for interchangability. For
example, a channel-facing end 126 of the neck portion 120 may include an
outwardly-projecting peripheral flange 128, and a neck-facing end 144 of the
channel portion 140 may include an inwardly-open circumferential track 146
which engages the peripheral flange 128 to interlock the neck portion 120 and
channel portion 140 together. It will be appreciated that the channel-facing
end
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126 of the neck portion 120 could include such a track, and the a neck-facing
end 144 of the channel portion 140 include such a projecting peripheral
flange,
to provide the same functionality. The neck portion 120 may be flexible enough
that the channel-facing end 126 and flange 128 may be compressed to fit within
the circumferential track 146. However, the channel portion 140 may comprise
separable halves 140a, 140b and be connectable by respective latching tabs
148a and ridged lands 149a (shown in Fig. 2) or U-shapes latch arms 148b and
locking ramps 149b (shown in Fig. 4). This construction permits the channel
portion halves 140a, 140b to be snapped around the peripheral flange 128 of
the
neck portion 120, and enables easy insertion of the metal nut 160 into the
channel 150 formed by the halves during manufacturing or user assembly.
Those of skill in the art will appreciate that the neck portion 120 and/or
channel
portion(s) 140 or 140a and 140b may be affixed to each other by solvent
welding, ultrasonic welding, adhesives, and similar known means for joining
materials so as to negate the need for one or more of the structures and
features
specifically described in this paragraph.
[0014] In some embodiments, the insert portion 100 includes a removable cap
portion 170 configured to seal the longitudinally elongated slot 130 opposite
the
longitudinally elongated channel 150. The removable cap portion 170 may be a
frangible part of the neck portion 120, defined by a thinned web or line of
perforation 172 (both indicated by the illustrated dashed line) proximate the
periphery of the elongated longitudinal slot 130. The cap portion 170 may be
removed by puncturing the portion with a tool such as a screw driver and
breaking the frangible web or line of perforation 172. The removable cap
portion 170 might include a pull-tab, e.g. a molded loop and stem attached to
the cap portion via a living hinge, configured to enable tool-less removal.
Alternately, the removable cap portion 170 might be a separate non-metallic or
metallic cap which snap-fits into engagement with the neck portion 120
opposite the channel portion 140. A separate, metallic removable cap 170, such
as a steel cap, could be detected by an appropriately calibrated metal
detector
and/or reused with other inserts 100 in subsequent forming activities.
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[0015] In some embodiments, the neck portion 120 includes a plurality of
outwardly-projecting tabs 125 opposite the channel-facing end 126. As shown,
the tabs include reinforcing gussets 125a and project longitudinally from the
neck portion 120. However, it will be appreciated that gussets 125a are
optional
and that tabs 125 may project longitudinally from the neck portion 120,
transversely from the neck portion 120, and/or at non-orthogonal angles with
respect to the longitudinal axis of the elongated longitudinal slot 130. The
tabs
125 are illustrated as including apertures, but it will be appreciated that
the
apertures may instead be thin webs or even omitted, with fasteners such as
nails
serving to form their own aperture when used to secure the insert 100 against
a
concrete form via the tabs. In other embodiments, the neck portion 120
includes an outwardly-projecting peripheral flange, opposite the peripheral
flange 128 at the channel-facing end 126, which may include similar apertures
or thin webs for receiving fasteners. For the purposes of the application and
claims, this peripheral flange shall be considered a generic case which
encompasses one or more outwardly-projecting tabs 125 of varying size.
[0016] In some embodiments, the channel portion 140 includes a plurality of
outwardly-projecting clips 145. The clips may serve to affix the insert 100 to
metal reinforcing bars or "rebar" positioned within the concrete form,
removing
the need to directly secure the insert 100 to a concrete form. It will be
appreciated that the insert 100 may be positioned directly adjacent a concrete
form, such as under a cap form or beside a wall form, through the clip-
connection while not being directly secured to the form itself In some
embodiments (not shown), mutually opposing pairs of clips 145 may be
disposed on the laterally outermost or longitudinally outermost sides of the
channel portion 140. In the illustrated embodiment, clips 145 are configured
to
receive metal reinforcing bars running parallel to the longitudinal axis of
the
channel 150, and also to project across a longitudinally-running, laterally-
projecting bearing surface 143 in the channel portion 140. The bearing surface
may further include a clip-opposing saddle 147 to maintain the metal
reinforcing bar in position. As explained below, in this embodiment the metal
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nut 160 may bear against the reinforcing rod to resist pull-out of the nut
from
the insert 100 and surrounding concrete.
[0017] The metal nut 160 is preferably a rectangular nut, but not necessarily
a
hyperrectangle or orthotope (i.e., not necessarily a strictly rectangular
box). In
some embodiments, metal nut 160 may be a rectangular nut with rounded edges,
such as a conventional square nut. In other embodiments, the metal nut 160
may include a rectangular portion but also include an integral shaft
structure,
such as in a T-slot nut, to provide greater load capacity to the aperture 164
of
the nut. The aperture 164 is typically threaded such that increasing the depth
of
the aperture will generally increase the load capacity of the metal nut 160.
In
the illustrated embodiment, the metal nut 160 includes a pair of
longitudinally-
running, laterally-projecting wings 163 which generally conform to the
longitudinally-running, laterally projecting bearing surfaces 143 in the
channel
portion 140. Metal reinforcing bars positioned upon the bearing surfaces 143
of
the channel portion will be disposed proximate the wings 163 of the nut 160,
and consequently the nut 160 will bear against those bars when a tensile load
is
applied to the aperture 162 by a threaded-bolt or threaded-bolt-type
connection
through the elongated longitudinal slot 130. In each such embodiment, the
aperture 162 is accessible through the longitudinally elongated slot 130 or
becomes accessible through that slot upon removal of the removable cap portion
170. In some embodiments, the metal nut 160 may include an elastomeric
spacer 166, e.g., a spacer formed from an elastomeric open-cell or closed-cell
foam, adhered to one of the non-longitudinal sides of the nut. The elastomeric
spacer 166 may be adhered to the nut using an adhesive, e.g., a pressure-
sensitive adhesive, and serve to increase friction between the metal nut 160
and
channel portion 140 in order to prevent unwanted sliding of the metal nut 160
within the channel 150. In other embodiments, the a channel-facing end 126 of
the neck portion 120 may include a plurality of elastic fingers 127 configured
to
project within the longitudinally elongated channel 150. The elastic fingers
127
will interfere with movement of the metal nut 160 within the channel 150, but
deflect when force is applied to the nut to move it within the channel 150,
e.g.,
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when a tool is used to positively manipulate the nut and/or an connected
element is positioned prior to tensioning of the connection. In still other
embodiments, a combination of such features can be used. The metal nut 160
may thus be manipulated to slide longitudinally within the channel 150, but
substantially prevented from sliding within the channel due to the force of
gravity or minor manipulation of the insert 100 during installation.
[0018] In use, an example of which is shown in Figure 3, a formwork 200 may
include the insert 100 and at least a pair of metal reinforcing bars 210
bracketing the void former 110 proximate the channel portion 140 and
longitudinally elongated channel 150 (shown in Fig. 2). At least those
portions
of the metal reinforcing bars 210 proximate the channel portion may be
configured to extend parallel to the longitudinal axis of the longitudinally
elongated channel 150. In some embodiments, the insert 100 is affixed to the
metal reinforcing bars 210 by wrapping the void former 110 and bracketing
metal reinforcing bars 210 with wire (not shown), for example in an X-shaped
pattern spanning the neck-facing end 144 and opposite end of the channel
portion 140, crossing itself midway along the longitudinally elongated channel
150 on the lateral sides of the channel portion 140. Preferably, the metal
reinforcing bars 210 are received within a plurality of clips 145 projecting
outwardly from the channel portion 140. Each metal reinforcing bar 210 is thus
clipped between a bearing surface 143 in the channel portion 140 and one or
more clips 145 on each side of the channel portion 210. The metal reinforcing
bars 210 may be positioned within surrounding concrete forms, e.g., opposing
wall forms 220 (only one of which is shown), and with the channel 150 of the
insert 100 at a depth "D" below the planned surface of the concrete ¨ which
may be formed by a cap form or, as indicated in the illustration, a free
surface of
the concrete "S". The removable cap 170 ends up proximate the free surface of
the concrete 230, and may be located by identifying the edges of the neck
portion 120 proximate the cap, by identifying the cap itself if visible, by
striking
the set concrete over the cap (which, being at most a thin layer over the non-
metallic void former 120, is likely to fracture and chip), or by locating
upwardly
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projecting whiskers 176 located on or near the removable cap 170. The
removable cap 170 may subsequently be removed to expose the metal nut for
connection to a threaded bolt or threaded-bolt-type connection.
[0019] In another use, an example of which is shown in Figure 4, a formwork
300 may include an insert 100 and at least one support member, such as the
previously illustrated wall form 220 or the illustrated support member 230.
The
insert 100 is secured directly to the member 230, with the neck portion 120
opposite the channel portion 140 positioned against the forming surface. In
one
embodiment, the insert is secured directly to the member 230 using a plurality
of fasteners 240 inserted through one or more outwardly-projecting tabs 125,
as
described above. The elongated longitudinal slot 130 may be substantially
sealed from exposure to concrete by the fit of the neck portion 120 against
the
member 230, by a removable cap 170, or by other means for forming a seal
such as a gasket, a caulk, a putty, a highly viscous grease or gel, etc. As
shown
in Figure 3 and/or discussed above metal reinforcing bars 210 could also be
secured to the insert 100 to reinforce the positioning of the insert and/or to
position the metal reinforcing bars 210 at a definite location within the
formwork 300. The neck portion 120 opposite the channel portion 140 ends up
proximate the formed surface of the concrete, and may be located by
identifying
the edges of the neck portion 120 and/or the elongated longitudinal slot 130
opening at the formed surface, by identifying any removable cap 170 provided,
by striking any concrete skin formed upon the removable cap, etc. The slot
opening to the metal nut 160 may then be used for connection to a threaded
bolt
or threaded-bolt-type connection.
[0020] Having described the invention in detail and by reference to the
preferred embodiments, it will be apparent that modifications and variations
thereof are possible without departing from the scope of this disclosure.
