Patent Application
20160017593
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.
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 Corewall® 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, 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.
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.
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 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.
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.
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 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.
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.
As shown in
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
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.
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.
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 nut 160 may bear against the reinforcing rod to resist pull-out of the nut from the insert 100 and surrounding concrete.
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., 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.
In use, an example of which is shown in
In another use, an example of which is shown in
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.
