AU666883B2

AU666883B2 - Concrete structures and related accessories

Info

Publication number: AU666883B2
Application number: AU28152/92A
Authority: AU
Inventors: Daniel Charles Underwood
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 1991-11-04
Filing date: 1992-11-04
Publication date: 1996-02-29
Anticipated expiration: 2012-11-04
Also published as: AU2815292A

Description

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AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT *a 0 Name of Applicant: Actual Inventor: Address for Service: Invention Title: Details of Associated Provisional Applications Nos: DANIEL CHARLES UNDERWOOD Daniel Charles Underwood TREVOR DREDGE ASSOCIATES Patent Trade Mark Attorneys 13th Floor, 379 Queen Street BRISBANE, QLD, 4000 (GPO Box 1339, BRISBANE, 4001) "Corcrete Structures and Related Accessories" PK9303 filed 4 November, 1991 PK9204 filed 4 November, 1991 PK9305 filed 4 November, 1991 The following statement is a full description of this invention, including the best method of performing it known to me: 2 "CONCRETE STRUCTURES AND RELATED ACCESSORIES" TECHNICAL FIELD OF THE INVENTION THIS INVENTION relates to concrete structures and related accessories for laying down concrete slabs and in particular to improvements in relation to key joints.

BACKGROUND ART At present, large floor areas of concrete are laid as slabs separated by key joints which allow relative movement between adjacent slabs while maintaining the slabs in alignment. Present key joints and the associated slabs employing the key joints have a number of undesirable features. For example, present key joints require skill to align and adjust their position and it would be desirable to provide a key joint which can be positioned using simplified procedures. Another problem arises due to stresses formed in adjacent slabs resulting in cracking or fractures forming adjacent the key joint. It would be desirable to reduce the S 15 likelihood of cracking or fracturing by improving the key joint and thereby improve the structure of the slab.

OUTLINE OF TI-HE INVENTION *o In one aspect, the present invention relates to the concept of locking a stake relative to a key joint by utilising a loc 'ng means which co-operates with 0: 0, t: 20 an aperture in the key joint and through which the stake passes to support the key Sjoint. In one aspect therefore, the present invention resides in a key joint p assembly having a key joint comprising a deformed sheet of metal defining an elongate channel and opposed projection extending generally parallel to upper and lower peripheral edges of the sheet, the sheet having a plurality of 3 longitudinally spaced pairs of opposed apertures and each pair of apertures having a stake passing through the apertures to support the key joint with the stake in a generally vertical position and stake locking means engaging the key joint adjacent the aperture to retain the key joint in a locked position relative to the stake.

The stake locking means can be part of the stake or part of the key joint or a combination of the two. For example, the stake locking means could be in the form of a deformable aperture which is deformed as a stake passes through same to frictionally hold the stake. The stake could include a knurled region to enhance the frictional engagement. Alternatively, the locking means could be separate from the stake or the key joint and in this embodiment, could include a small wedge which can be driven into the aperture between the anerture and the stake to lock the stake in place. However, it is preferable to employ a stake which includes the locking means as part of the stake.

15 The stake locking means can automatically engage the stake as the stake *see*: passes through apertures in the key joint. The locking means can engage the e :stake by virtue of strategically placed projections that resiliently hold, grip or deform the key joint to frictionally lock the stake to the key joint. Alternatively, the stake loclking means can be manually moved between locked and released 20 positions. Typically, the locking means accommodates a range of key joint positions relative to the stake by providing a plurality of selectable locking sites i along the rod. The locking sites can provide a plurality of projections or grooves S S which deform the key joint as the locking means is moved to the locking position or alternatively, a minimum of deformation or no deformation need occur. For 4 example, a typical locking site could comprise opposed or opposed and offset radiused grooves so that on rotation of the stake, the stake moves between the released and locked positions.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the present invention can be more readily understood and be put into practical effect, reference will now be made to the accompanying drawings and wherein:- Figure 1 is a pictorial view illustrating a key joint according to the invention; Figure 2 is a pictorial view illustrating a partially completed concrete constructicn employing a key joint assembly according to the present invention; Figure 3 is a pictorial view illustrating a stake for the key joint assembly according to the present invention; :Figure 4 is an enlarged view of a portion of the stake of Figure 3; Figure 5 is an end view of the stake of Figure 3; o *Figures 6 and 7 are pictorial views illustrating use ofthe stake of Figure 3; oo Figure 8 is a pictorial view illustrating an insert for the key joint assembly

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according to the present invention; and Figure 9 is a sectional view illustrating an insert for the key joint assembly 20 according to the invention showing the insert coupled to a stake.

METHOD OF PERFORMANCE

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Referring to the drawings and initially to Figure 1, there is illustrated a key

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joint 10 comprising a folded sheet of metal having a channel 11 and on its opposite side a projection 12. The key joint 10 includes a plurality of square S t apertures 13, each aperture having a hcrizontal edge 14 so that a square section dowel passing through an aperture 13 will have one of its flat surfaces located in a horizontal plane. The apertures 13 can be punched into the metal as "knockouts" 13' (see Figure 6) or can be partial "knock-outs" in the form of hinged closures that can be set at 900 to the key joint to provide a horizontal seat to which a dowel passing through the aperture can be secured.

Referring to Figure 2, there is illustrated a partially completed concrete structure 15 employing the key joint 10 of Figure 1. As can be seen, the structure comprises a horizontal slab of concrete 16 having the key joint 10 defining an edge of the slab 16. A plurality of square section dowels 17 are shown projecting from the slab at spaced, intervals along the slab. The key juint 10 is retained in place prior to pouring the slab 16 using stakes 18 which pass through opposed elongate apertures 19 in the key joint and are embedded in the ground beneath the slab. The inclusion of the stake 18 serves to provide a simplified key joint S: 15 layout and a more stable layout of key joint and dowels prior to pouring the slab S•16. Details of the operation of the stake 18 will be described below.

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o".Figure 2 shows dowels 17 capped with a cap 20 which can be made from expanded polystyrene foam or other compressible filler so as to create a concrete 0o: free gap 21 beside each dowel 17. Three dowels 17 are illustrated in Figure 2, 20 one in phantom along with a phantom cap 20, one with the dowel and cap fitted and one with the cap omitted. The caps 20 can be applied to the dowels on both sides or on one side of the key joint only. The phantom outline serves to illustrate the arrangement on both sides.

As can be seen, the slab 16 can partially cure prior to an adjacent slab r 6 which will embrace the projecting dowels being poured. As the two slabs cure at different rates, relative displacement of the dowels will be accommodated by the gaps 21 or compression of the filler provided by the caps Referring to Figures 3 to 5, there is illustrated a stake 18 for a preferred embodiment of the present invention, the stake 18 comprises a cylindrical steel rod having a shank portion 22 which can be driven into the ground and locking means 23 including a plurality of selectable locking sites in the form of a plurality of grooves 24 which are opposed and offset (see Figure The locking means 23 includes opposed flats 25 so that the stake can freely slide through the elongate apertures 19 in a key joint 10 but on rotation, edges of the elongate apertures 19 frictionally engage in the grooves 24. The grooves 24 are radiused as shown in phantom at 26 in Figure 5 so that edges of the elongate apertures 19 in the key joint 10 suffer minimum deformation as the stake 18 is rotated to lock the stake 18 to the key joint 15 Referring to Figures 6 and 7, use of the stake 18 is illustrated. In use, the stake 18 is first driven into the ground with a key joint 10 slid over the top so it sits on the shoulder 27 (see Figure 3) of the stake 18 at the transition from the o° flats 25 to the shank 22. As can be seen in Figure 6, the key joint 10 includes a pair of elongate apertures 19 through which the stake 18 passes from below.

20 A plurality of stakes 18 are inserted through the key joint in this way so the key joint 10 is supported by stakes 18 at spaced locations along the key joint Once all the stakes 18 are in place in their released position, as shown in Figure 6, an operator can then slide the key joint 10 to its desired position on each stake 18 and lock the key joint 10 to the stake 18 by rotating the stake 18 using a suitable tool.

It will be appreciated that any form of locking means 23 can be employed.

For example, the locking means 23 could comprise a knurled surface so that as the stake 18 is driven through the key joint 10, the elongate aperltures 19 are S deformed to automatically engage the knurled surface. Furthermore, although the stake 18 is shown locked to both elongate apertures 19, it need only lock with one of the elongate apertures 19.

In the illustrated embodiment, the stake 18 is of constant diameter throughout, thus requiring the key joint 10 to be slid over the stake 18 from above but this need not be the case. For example, the opposed flats 25 could be flattened using a rolling process and made wider so that the cylindrical shank portion 22 and the opposed flats 25 could both be made to pass through the elongate apertures 19 while the stake 18 is in the position illustrated in Figure 6 prior to rotation to the position illustrated in Figure 7.

1 5 Referringto Figure 8, there is illustrated a key joint assembly 28 employing S* a key joint 10, a stake 18 supporting the key joint 10 in a generally vertical 0o attitude and an insert 29 according to a preferred embodiment of the present invention. The insert 29 is extruded from a plastics or rubber material and includes a body 30 which is generally U-shaped in transverse section. The insert 20 29 is shown in phantom in its operative position clipped onto the stake 18 by elongate clip 31 (see also Figure 9).

The insert includes flexible flanges 32 which, as shown in phantom, flare out against the key joint when the insert is in place (see also Figure 9).

Figure 9 illustrates in phantom the flaring action of the flexible flanges 32 I f

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8 when the insert is used with a smaller key joint There are of course, many other mechanically equivalent inserts including wedging inserts which can fill a space 33 behind the stake 18 rather than create a cavity as in the illustrated embodiment. Moreover, while the illustrated embodiment describes a hand insertable insert, inserts that are placed with the assistance of a tool, for example driven into place with a hammer, are also within the scope of the present invention.

Whilst the above has been given by way of illustrative example of the present invention, many variations and modifications thereto will be apparent to those skilled in the art without departing from the broad ambit and scope of the invention as set forth in the appended claims.

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Claims

1. A key joint assembly having a key joint comprising a deformed sheet of metal defining on one side an elongate channel and on its opposite side an elongate projection extending generally parallel to upper and lower peripheral edges of the sheet, the sheet having a plurality of longitudinally spaced pairs of opposed apertures arid each pair of apertures having a stake passing through the apertures to support the key joint in a generally vertical position and said stake having stake locking means engaging the key joint adjacent at least one of the apertures to retain the key joint in a locked position relative to the stake.

2. A key joint assembly according to claim 1 wherein the stake comprises an elongate rod having opposed ends, a shank portion adjacent one end and the S: stake locking means adjacent its other end, so that in use, the stake can be driven into the ground and the locking means can engage the key joint to lock the key joint to the stake. *o o*

3. A key joint assembly according to claim 1 or claim 2 wherein the locking means comprises strategically placed projections that resiliently hold, grip or deform the key joint to frictionally lock the stake to the key joint. .t

4. A key joint assembly according to claim 1 or claim 2 wherein the locking means accommodates a range of key joint positions relative to the stake by providing a plurality of selectable locking sites along the rod. A key joint assembly according to claim 4 wherein the locking sites comprise opposed or opposed and offset radiused grooves so that on rotation of the stake, the stake moves between released and locked positions. DATED this 21 st day of September, 1995. DANIEL CHAMLES UNDERWOOD By his Patent Attorneys INTELLPRO ft 06 #9 46 00 ft **ace:ft