WO2023283696A1

WO2023283696A1 - Attachment for positioning cast-in-place anchor bolts, supporting a setdown and associated methods

Info

Publication number: WO2023283696A1
Application number: PCT/AU2022/050747
Authority: WO
Inventors: Hayden Charles JUREY
Original assignee: Threadlegs Pty Ltd
Priority date: 2021-07-16
Filing date: 2022-07-15
Publication date: 2023-01-19

Abstract

An attachment for positioning a cast-in-place anchor bolt relative to concrete formwork prior to pouring of concrete therein, comprising: an upper body having an opening for receiving and supporting a lower end of the bolt such that it is spaced from the 5 formwork; legs extending downwardly from the upper body; and a substantially continuous base configured for, in use, placement against and securement to formwork so as to fix a position of the bolt relative thereto, the base being associated with respective lower ends of the legs so as to maintain the upper body thereabove.

Description

ATTACHMENT FOR POSITIONING CAST-IN-PLAGE ANCHOR BOLTS, SUPPORTING A SETDOWN AND ASSOCIATED METHODS

FIELD OF THE INVENTION

The present patent specification relates to an attachment for positioning cast-in place anchor bolts such as hold down bolts (also known via other terms, such as cast-in threaded anchors and rag bolts). In an embodiment, the attachment is securable to a base of cast-in threaded rods, and is securable to concrete formwork to fix a position of the rod prior to the pouring of concrete into the formwork.

BACKGROUND

Figure 1 shows threaded anchor bolts 2 cast in a concrete base 4. The anchor bolts enable a steel column 6 to be secured to the concrete base. Before casting the concrete base 4, each anchor bolt 2 ought to be precisely positioned relative to associated concrete formwork and/or reinforcement such that, after the concrete 4 cures, the anchor bolts 2 protrude out from the concrete 4 at locations that enable the anchor bolts 2 to pass through openings formed in a base of the steel column 6. In essence, it is important to ensure accurate positioning of cast-in-place anchor bolts 2 before and during pouring of concrete so that the anchor bolts 2 are not displaced from their intended positions. Otherwise, the anchor bolts 2 may not be adequately positioned to secure the intended structures.

Figure 3 shows what can occur when the anchor bolts 2 are displaced from their intended positions. In this Figure, the four bolts 2' have shifted relative to their intended locations, and as such, one or more of the bolts 2' cannot be received in a corresponding preformed hole in a base of the steel column 6. Instead, structural modifications have been made to the base of the steel column 6 to allow it to be secured via the displaced bolts 2'. It is thus important to ensure the precise positioning of anchor bolts 2 before, during and after the pouring of concrete, so that they are not displaced from their intended positions. Displaced anchor bolts 2' may result in compromised structures that require additional resources, engineering and labour to address, and can pose safety risks.

Figure 2 shows four threaded rods 3 positioned relative to concrete formwork 8 and reinforcement 10. The lower end of each rod 3 is provided with a steel plate 12 sandwiched between an upper nut 14 and a lower nut (not shown). The tip of the lower end of each rod 3 (not shown) typically extends beyond the lower nut and is exposed to the open air. In positioning each rod 3, the lower ends of each rod 3are suspended above the formwork 8 so that when the concrete slab is poured, the lower end of the rods 3are covered by and completely encased in the concrete slab. This ensures the lower ends of the rods 3 are protected in the concrete slab and not exposed to the elements, whereby corrosion can occur to the rods 3 and connecting reinforcement within the slab.

However, the need to keep the threaded rods 3 suspended above the formwork 8 makes it difficult to fix the position of each rod 3 relative to the surrounding reinforcement 10 and/or formwork 8. As such, during construction and installation of the concrete reinforcement 10, formwork 8, associated plumbing, wiring and the like, and also during pouring of concrete, the rods 3 may be displaced from their intended positions. Figure 2 shows cable ties 16 being used in an attempt to secure the rods 3 to adjacent reinforcement 10. Of course, cable ties 16 are relatively weak and are prone to breakage or movement.

There is a need to address the above, and/or at least provide a useful alternative.

SUMMARY

According to a first aspect of the present invention, there is provided an attachment for positioning a cast-in concrete anchor relative to concrete formwork prior to pouring of concrete therein, comprising: an upper body having a threaded opening for securing to a lower end of the anchor; and a base associated with the body and configured for, in use, placement against and securement to formwork so as to fix a position of the anchor relative thereto. According to embodiments of the invention, the base comprises one or more features configured for alignment with respective indicators provided on the formwork.

According to embodiments of the invention, the features comprise respective indentations formed in the base. The features may assist with alignment of the anchors with markings premarked on the formwork indicating intended anchor installation positions.

According to embodiments of the invention, the attachment further comprises legs extending downwardly from the body, wherein the base is generally ring-shaped and associated with lower ends of the respective legs such that the legs maintain the body at a height above that of the base.

According to embodiments of the invention, the base comprises one or more openings through which fasteners can be driven to secure the attachment to formwork.

According to embodiments of the invention, the openings are disposed at respective quadrants of the base.

According to embodiments of the invention, each feature of the base is associated with a respective opening.

According to embodiments of the invention, the base comprises a wall extending upwardly from an outer perimeter of the base.

According to embodiments of the invention, the wall comprises the one or more features.

According to embodiments of the invention, the features are symmetrically disposed about an outer perimeter of the base. According to a second aspect of the present invention, there is provided a method of securing a cast-in concrete anchor relative to concrete formwork prior to pouring of concrete therein, comprising: securing the attachment according to a first aspect of the present invention to a lower end of the anchor; and fixing the attachment to concrete formwork such that the anchor is spaced from the formwork.

According to embodiments of the invention, the method further comprises: prior to fixing the attachment, marking the formwork to indicate a position that the attachment and/or associated anchor is to be secured; and aligning features of the attachment with the marking.

According to a third aspect of the present invention, there is provided a method of supporting a setdown above concrete reinforcement prior to pouring of concrete, comprising: securing the attachment of any one of claims 1 to 10 to a lower end of a threaded anchor provided with a height adjustment means; securing an upper end of the anchor to the setdown such that it rests on the height adjustment means; and adjusting the height adjustment means such that the attachment is positioned on a base underlying the concrete reinforcement and the setdown is positioned at a desired height above the reinforcement.

According to embodiments of the invention, the height adjustment means comprises a nut that is rotatable along the threaded anchor to effect height adjustment of the setdown. BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure l is a front view of a steel column fixed to a concrete base via anchor bolts cast in the concrete base;

Figure 2 is a top perspective view of four threaded rods positioned relative to concrete reinforcement, lower ends of each anchor being suspended above concrete formwork;

Figure 3 is a side perspective view of a steel column secured to a concrete base via anchor bolts, all of which are displaced from their intended positions;

Figure 4 is a front perspective view of an attachment according to embodiments of the present invention;

Figure 5 is a top view of the attachment of Figure 4;

Figure 6 shows the present attachment supporting setdowns relative to concrete reinforcement;

Figure 7 shows the present attachment supporting a plate relative to concrete reinforcement;

Figure 8 is a cross sectional view of an alternative attachment;

Figure 9 is a cross sectional view of another alternative attachment; and

Figure 10 is a bottom perspective view of further alternative attachment.

DETAILED DESCRIPTION

Figures 4 and 5 show an embodiment of the present attachment 18. The attachment 18 is configured to attach to a lower end of a cast-in-place anchor bolt 2. The attachment 18 can then be fixed, for example, to adjacent formwork, thereby fixing a position of the anchor bolt 2 relative to the concrete formwork. As will be discussed, the attachment 18 can also be configured to attach to a lower end of threaded rod 3 for the purposes of supporting a setdown above concrete reinforcement prior to pouring of concrete. Referring to Figure 4, in one embodiment, the attachment 18 may be integrally formed from a material that is not vulnerable to corrosion, such as plastic. The attachment 18 comprises a generally cylindrical, upper body portion 20, having a centrally disposed through hole 22. In the embodiment of Figures 4 and 5, the hole 22 is threaded, though in other embodiments such as those shown in Figures 8 and 9 it is not. The threaded hole 22 allows the attachment 18 to screw onto a lower end of an anchor bolt 2. Of course, the attachment 18 may be formed in different sizes, with different thread configurations and the like to suit the bolt 2 to which it is to be secured. Advantageously, before securing the attachment 18 to adjacent formwork, the attachment 18 can be screwed up and down the threaded anchor bolt 2 to adjust a vertical position thereof.

This adjustment process can help to vertically level a group of anchor bolts 2.

An upper surface 24 of the body 20 is generally flat, thereby allowing the upper surface 24 to be positioned relatively flush against other attachments, such as steel plates 12 and spacers (see Figure 2) and the like.

Extending downwardly from an exterior of the upper body 20 are four, generally vertical legs 26 with a ribbed configuration. The legs 26 are preferably equispaced around a circumference of the upper body 20. The height and angle of the legs 26, among other parameters, may of course be varied to suit the specific application.

Between adjacent legs 26 are respective openings that allow for concrete and aggregate to encapsulate the attachment 18 and thus the anchor bolt 2 during use.

The attachment 18 also comprises a base 28 via which the attachment 18 can be fixed to adjacent formwork. Preferably, the base 28 is substantially continuous, and may be generally symmetrically disposed about the upper body 20 to promote even encapsulation within the poured concrete. In the Figures, the base 28 is generally ring- shaped and extends around and from a base or lower end of each of the four legs 26.

The base 28 defines an annular platform that can be placed against and secured to formwork. For example, the base 28 preferably has a generally flat bottom surface upon which the attachment 18 can sit stably and securely on formwork (though another embodiment with a different configured base 28 is later discussed with reference to Figer 10).

The legs 26 extend upwardly from the base 28 and maintain the upper body portion 20 at a height above a height of the base 28. This allows a lower end of the threaded anchor bolt 2 to be offset or raised from the formwork to prevent corrosion thereof. In practice, the attachment 18 is configured to space or maintain the lower end of the threaded anchor from the formwork by at least 30mm.

The base 28 comprises a generally planar ring-shaped surface 30, wherein quadrants thereof are provided with respective openings or holes 32 through which fasteners can be driven to secure the attachment 18 to adjacent formwork. Of course, the attachment 18 need not have the holes 32 preformed therein; for example, the quadrants of the base can simply be drilled through during the fastening process. In the Figures, the base 28 comprises bulges proximate each through hole 32 so that the planar surface 30 of the base 28 provides sufficient surface area to receive, for example, a head of the fastener (e.g., the head of a screw or nail). Although shown as a ring, the base 28 may take other forms, such as oblong, square or rectangular for example.

A substantially continuous wall 34 extends upwardly from an outer perimeter of the base 28 and helps to strengthen the base 28. The wall 34 is provided with features 36 which can be aligned with indicators on the formwork to help position the attachment 18 and thus the associated anchor bolt 2 at its intended position.

In Figure 4, the features are depicted as vertically extending indentations or grooves 36 formed in the upwardly extending wall 34 of the base 28. In particular, the grooves 36 are disposed symmetrically about the wall 34. In the Figures, a groove 36a is positioned proximate a respective through hole 32. Additional grooves 36b in the wall 34 are formed at positions generally equidistant between adjacent through holes 32. As such, the four grooves 36a align with one another to define an imaginary cross. Similarly, the four grooves 36b align with one another to define a second imaginary cross, offset from the first-mentioned cross by about 45 degrees.

In use, a surveyor or the like may mark, e.g. with a pencil, a cross on the formwork indicating where each attachment 18 and thus anchor bolt 2 is to be positioned. The grooves 36a or 36b of the attachment 18 may thus be easily visually aligned with the marked cross, and thereafter secured to the formwork at the intended position.

The present attachment 18 allows the position of a respective anchor bolt 2 to be fixed relative to concrete formwork and/or reinforcement, while still allowing the lower end of the anchor bolt 2 to be held above the formwork upon which the concrete will be poured. As such, after the concrete is poured, the lower end of the anchor bolt 2 will still be encased in the concrete slab and thus remains protected from the elements. The base 28 of the plastic attachment 18 may be exposed to the elements but is advantageously not vulnerable to corrosion. Alternatively, if the attachment 318 comprises projections extending downwardly from the base (as in Figure 10), then it would be the projections that are exposed to the elements, which projections also are not vulnerable to corrosion. It will be noted that the depicted attachment 18 is generally open (e.g., the legs 26 are spaced from one another and the base 28 is ring-shaped as opposed to being a closed or solid circular shape) to allow concrete and aggregate to flow within and around the attachment 18 while minimising the formation of air pockets and cavities in the resulting concrete structure.

Figure 8 illustrates an alternative attachment 118. In relation to this embodiment, like features are shown with reference numerals incremented by 100 and the preceding description of those features are intended to apply.

In this embodiment, attachment 118 has an upper body portion 120 that is formed with a cavity 122 without an internal thread formed therein. To secure a threaded rod 3 in place, a nut 150 is provided on an underside of the upper body portion 120. A second nut 152 on the upperside of the upper body portion 120 may also be provided. Those skilled in the art will appreciate that nuts 150, 152 function as per the hole 122 to securing an end of the threaded rod 3.

Figure 9 illustrates a further alternative attachment 218. In relation to this embodiment, like features are shown with reference numerals incremented by 200 and the preceding description of those features are intended to apply.

As per attachment 118, attachment 218 has an upper body portion 220 that is formed with a cavity 222 without an internal thread formed therein. The cavity 222 has a lower surface 248 on which an end of the threaded rod 3 will sit. Cavity 222 may be sized so as to be a close fit with an outer diameter of the threaded anchor 2 to position and support the threaded anchor 2 without a threaded engagement. To accommodate threaded rods of different sizes, differently sized inserts may be used in cavity 222.

Many modifications of the above embodiments will be apparent to those skilled in the art without departing from the scope of the present invention. For example, while the attachment 18 has been described in relation to concrete formwork, the attachment 18 may of course also be used where a sand or earth-based subgrade is used as a base for footings, foundations and ground slabs.

While the attachment 18 has primarily been described in relation to fixing a position of cast-in-place anchor bolts 2, the attachment may be used in other applications. One such application is illustrated in Figure 6. Figure 6 shows timber setdown 38 suspended above reinforcement 10. The setdown 38 is commonly suspended via conventional bar chairs 40. Flowever, bar chairs 40 are not height adjustable, and so methods for suspending the setdown 38 at different heights is often improvised. For example, in Figure 6, the frontmost setdown is suspended via a cut piece of PVC piping 42. The present attachment 18 can be utilised to suspend setdown 38 at the desired height. In this regard, a threaded rod 3 and nut 14 can be secured to the setdown 38 for support thereof. An attachment 18 can be secured to a base of the rod 3. The nut 14 can be screwed up and down the rod 3 to adjust a height at which the setdown 38 is installed.

Figure 7 shows another application in which the present attachment 18 may be utilised. In this case, a steel column 6 is to be mounted on a steel plate 44 suspended above concrete reinforcement 10. In instances where legs 2b of the steel plate 44 are threaded, the attachments 18 can be secured to a lower ends of the legs and be rotated thereabout to allow for vertical adjustment of the plate 44.

Figure 10 illustrates a further alternative attachment 318. In relation to this embodiment, like features are shown with reference numerals incremented by 300 and the preceding description of those features are intended to apply. In this embodiment of the attachment 318, an underside of the base 328 is provided with one or more downwardly extending projections 354 configured to press against the formwork when installed, allowing concrete to pass between the projections 354 and the base 328 so that when formwork is stripped away, the base 328, or a substantial portion thereof, is not visible and/or exposed.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Claims

CLAIMS:

1. An atachment for positioning a cast-in-place anchor bolt relative to concrete formwork prior to pouring of concrete therein, comprising: an upper body having an opening for receiving and supporting a lower end of the bolt such that it is spaced from the formwork; legs extending downwardly from the upper body; and a substantially continuous base configured for, in use, placement against and securement to formwork so as to fix a position of the bolt relative thereto, the base being associated with respective lower ends of the legs so as to maintain the upper body thereabove.

2. The atachment of claim 1, wherein the opening of the upper body is configured to threadingly secure to a lower end of the bolt.

3. The atachment of claim 1 or 2, wherein the base comprises one or more features configured for alignment with respective indicators provided on the formwork.

4. The atachment of claim 3, wherein the features comprise respective indentations formed in the base.

5. The atachment of any one of the preceding claims, wherein the base is generally ring-shaped.

6. The atachment of any one of the preceding claims, wherein the base comprises openings through which fasteners can be driven to secure the attachment to formwork.

7. The atachment of claim 6 as appended to claim 5, wherein the openings are disposed at respective quadrants of the base.

8. The atachment of claim 6 or 7 as appended to either of claim 3 or 4, wherein each feature of the base is associated with a respective opening of the base.

9. The atachment of any one of the preceding claims, wherein the base comprises a wall extending upwardly from an outer perimeter of the base.

10. The atachment of claim 9 as appended to claim 3 or 4, wherein the wall comprises the one or more features.

11. The atachment of claim 3 or 4, wherein the features are symmetrically disposed about an outer perimeter of the base.

12. A method of securing a cast-in-plate anchor bolt relative to concrete formwork prior to pouring of concrete therein, comprising: Securing the atachment of any one of the preceding claims to a lower end of the anchor bolt; and fixing the atachment to concrete formwork such that the anchor bolt is spaced from the formwork.

13. The method of claim 12, further comprising: prior to fixing the atachment, marking the formwork to indicate a position that the atachment and/or associated anchor is to be secured; and aligning features of the atachment with the marking.

14. A method of supporting a setdown above concrete reinforcement prior to pouring of concrete, comprising: securing the atachment of any one of claims 1 to 11 to a lower end of a threaded rod provided with a height adjustment means; securing an upper end of the rod to the setdown such that it rests on the height adjustment means; and adjusting the height adjustment means such that the attachment is positioned on a base underlying the concrete reinforcement and the setdown is positioned at a desired height above the reinforcement.

15. The method of claim 14, wherein the height adjustment means comprises a nut that is rotatable along the threaded rod to effect height adjustment of the setdown.