NZ561447A

NZ561447A - Prop anchor

Info

Publication number: NZ561447A
Application number: NZ561447A
Authority: NZ
Inventors: Justin Vyt Zakaras; Barry William Crone
Original assignee: Itw Construction Products Australia Pty Ltd
Priority date: 2006-09-18
Filing date: 2007-09-13
Publication date: 2009-01-31

Abstract

An anchor for the foot plate of a prop used to provide temporary support for pre-cast concrete wall panels during the erection of concrete structures is disclosed. The prop anchor includes an internally threaded ferrule with a base (4) that provides stable support when placed on a casting surface for a concrete slab. The anchor includes a base part (6) co-operable with the ferrule to locate the ferrule on the casting surface, and a tubular void former (8). The void former allows a void to form between the ferrule and the upper surface of a slab cast on the casting surface, so that a prop resting on the slab can be retained in position by means extending through the void into threaded engagement with the ferrule.

Description

NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION 5614*7 After Australian Provisional Application No. 2006905132 filed 18 September 2006 Davies Collison Cave Reference: 30333897 APPLICANT(S) ITW Construction Products Australia Pty Ltd 3 Chester Street, Oakleigh, Victoria 3166, Australia An Australian company My/Our contact address is: DAVIES COLLISON CAVE 1 Nicholson Street G.P.O. Box 4387QQ Melbourne 3000 Victoria, AUSTRALIA Telephone: 61 3 9254 2777 Facsimile 61 3 9254 2770 Email: mail@davies.com.au INVENTION TITLE: My/Our address for service is: DAVIES COLLISON CAVE c/- James & Wells Level 9, James & Wells Tower 56 Cawley Street Private Bag 11907 DX CP 34005 Ellerslie Auckland NEW ZEALAND Prop anchor We/I, ITW Construction Products Australia Pty Ltd hereby declare the invention for which we pray that a patent be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: INTELLECTUAL PROPERTY OFFICE OF N.2. 13 SEP 2007 RECEIVED P:\REC\NZ\Docs\30333S97 253.doc • U/9/07 p\OPERVRSHU0327462-CAP.doc-6AW/2f>l]7 *10054637714* ",A~ 56 1 4 ^ 7 PROP ANCHOR The present invention relates to an anchor for the foot plate of a prop as may be used to provide temporary support for pre-cast concrete wall panels during the erection of concrete 5 structures.

During the erection of a building structure from pre-cast concrete wall panels, it is necessary for individual panels to be braced in their erected state until such time as the panels are interconnected to provide the required structural integrity. For this purpose, 10 each panel is supported by inclined props extending between an upper part of the panel and a floor slab on which the panels stand. Typically, a plate at the upper end of the prop is bolted into an internally-threaded ferrule cast into the wall panel during manufacture, and a foot plate at the lower end of the prop is normally secured to the slab by means of an anchor of expansion type within a hole drilled into the slab. While an expansion anchor 15 does provide a satisfactory anchorage for the foot plate, it requires the concrete of the slab to have attained its full strength in order to provide its rated anchoring capability. This, of necessity, requires the slab to be laid for a time prior to erection of the wall panels and sufficient to enable the concrete in the slab to cure to its full strength.

Construction time could be reduced by erection of the panels while the slab is still in a "green" or low strength condition. To the Applicant's knowledge, there are no commercially available anchoring systems which are capable of providing secure anchorage of the foot plate of the prop in these conditions.

According to the present invention there is provided a prop anchor comprising an internally-threaded ferrule having a base to provide stable support for the ferrule when placed on a casting surface for a concrete slab, means co-operable with the ferrule to locate the ferrule on the casting surface, and a tubular void former to form a void extending between the upper surface of a slab cast onto the casting surface and the ferrule, whereby a 30 prop resting on the slab can be retained in position by means extending through the void into threaded engagement with the ferrule.

P:\OPER\RSHV103274ft2-CAP.doc-C»AK)/21K)7 Accordingly, with the ferrule resting on the casting surface and thereby being at the maximum possible depth of embedment within the slab, it has the capability of providing 5 secure anchorage for a foot plate of a prop before the slab has attained its full strength.

Further according to the invention, there is provided a prop anchor comprising an internally-threaded ferrule having a base to provide stable support for the ferrule when placed on a casting surface for a concrete slab, and a support/void former assembly co-10 operable with the ferrule and comprising a base part securable to the casting surface to locate the ferrule on the casting surface and to hold the ferrule against rotation, the base part having a tube engageable over the ferrule, the assembly further comprising an extension tube fitted to the tube of the base part to form a void extending between the upper surface of a slab cast onto the casting surface and the ferrule, the void serving to 15 receive a threaded rod or bar engageable with the ferrule and by which the foot plate of a prop resting on the slab can be retained.

In a preferred embodiment of the invention, the base of the ferrule has a sufficient surface area to provide the required anchorage within the slab without the necessity of tying the 20 ferrule to the reinforcement, although that could be done if required.

Preferably, the base part of the support/void former assembly includes a tube designed to fit over an upper part of the ferrule and the tubular void former is fitted to the tube of the base part to form an extension thereof.

In a practical embodiment of the invention, the ferrule is designed for use with a threaded rod or bar of a diameter less than that of expansion anchors by which the foot plates of existing props are secured. Accordingly, the prop anchor of the preferred embodiment also includes a nut designed to take up clearance between the threaded rod/bar and the sides of 30 a standard slot in the foot plate of a prop. The nut is the form of a shouldered nut, having a tapered collar extending beneath the shoulder to inter-fit between the rod/bar and the sides P:\OPER\RSH\30327462-C AP.d0C*<»/0Stf2<)07 of the slot in the foot plate. Preferably, the nut is a wing nut.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a side view of a ferrule of a prop anchor in accordance with the preferred embodiment of the invention; Figure 2 is a perspective view of the ferrule shown in Figure 1; Figure 3 is a side view showing a support/void former assembly when applied to the ferrule - this Figure also shows how the anchor co-operates with the foot plate of a 10 prop; Figure 4 is a cross-section showing the support/void former assembly when applied to the ferrule; Figure 5 is a perspective view corresponding to Figure 4; Figure 6 is a perspective view of the base part of the support/void former assembly; and Figure 7 is a side view of a shouldered wing nut used to secure the foot plate of the prop.

The anchor comprises an internally-threaded ferrule 2, having a large area base 4 which 20 provides stable support for the ferrule when the base is resting on the casting surface, the base 4 also being of a size such as to provide secure anchorage for the ferrule within the slab even in conditions where the slab has not attained its full strength. The thread within the ferrule is designed to accept either a threaded rod or reinforcing bar having a partial or continuous thread such as that sold under the trade mark "Reidbar" by Reid Construction 25 Systems of Mooroolbark, Victoria.

The ferrule 2 is associated with a support/void former assembly consisting of a base part 6 which locates the ferrule 2 on the casting surface, and an extension tube 8 which fits onto the base part 6 to define within the cast slab a passage for the threaded rod or reinforcing 30 bar between the upper surface of the slab and the ferrule 2. The base part 6 comprises a lower, substantially planar, portion 10 of annular form, designed to sit on the casting PAOPER\RSHVK»274A2-CAP dccA/wmV surface around the base 4 of the ferrule 2 so as to locate the ferrule 2. It is secured to the casting surface either by means of nails or by means of pop rivets if the casting surface is made of steel. In the form shown, the base 4 of the ferrule 2 is not entirely circular, but is flattened in three zones and the interior of the annular portion 10 of the base part is 5 similarly shaped so that it co-operates with the base of the ferrule to hold the ferrule against rotation. The base part 6 also carries, via legs 12, a tubular support 14 which is designed to fit over the upper part of the ferrule 2. Accordingly, when the ferrule 2 is applied to the casting surface and the base part 6 is applied over the ferrule and fixed to the casting surface, the ferrule will be securely held in position.

The tubular support 14 of the base part 6 is inwardly stepped at its upper end to receive the extension tube 8. The base part 6 and the extension tube 8 are each formed as one-piece plastics mouldings, and the extension tube 8 is preferably formed with markings along its length to facilitate cutting of the tube to the required length corresponding to the depth of 15 the slab to be cast. A cap 16 is provided to close the upper end of the extension tube 8 to prevent ingress of concrete during casting, the cap 16 being removed after casting to thereby expose the passage leading from the surface of the cast slab to the ferrule 2.

To use the anchor when the slab has attained sufficient strength after casting, the threaded 20 rod or reinforcing bar 18 of required length is inserted through the passage within the tube 8 and screwed into the ferrule 2. The foot plate 20 (see Figure 3) of the prop is moved into position so that the upper end of the threaded rod/bar 18 engages into a slot in the foot plate and then a nut 22 is applied to lock the foot plate. As shown, the nut 22 is in the form of a shouldered wing nut, to permit initial tightening by hand prior to application of a 25 wrench for final tightening. A tapered collar 24 extending beneath the shoulder of the nut is of a size to inter-fit between the rod/bar 18 and the sides of the slot in order to take up any clearance between the two. In this regard, it is to be noted that the foot plates of most props currently available have been designed for use with expansion anchors which are of a larger overall diameter than that needed for the threaded rod/bar of the anchor system of 30 this invention and, accordingly, the slot in the foot plate will have a width greater than the diameter of the rod/bar.

P \0PER\RSH\3(tf 27462.CAP.doc-6/09/2007 With the prop anchor of the preferred embodiment of the invention, the large area base of the ferrule is embedded to the maximum possible depth of embedment from the upper surface of the slab, and the anchorage effect thereby is sufficient to retain the prop when 5 the slab has attained a pre-determined strength less than its maximum strength. On completion of the structure, the prop can be removed by unscrewing the nut and the threaded rod/bar can then be unscrewed from the ferrule and removed, with the passage extending into the ferrule through the tube then being filled.

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

Claims

P'\OPERVRSH\30327462-CAP.d«-6/t>9/2 1. A prop anchor comprising an internally-threaded ferrule having a base to provide stable support for the ferrule when placed on a casting surface for a concrete slab, means 5 co-operable with the ferrule to locate the ferrule on the casting surface, and a tubular void former to form a void extending between the upper surface of a slab cast onto the casting surface and the ferrule, whereby a prop resting on the slab can be retained in position by means extending through the void into threaded engagement with the ferrule. 10
2. A prop anchor according to claim 1, wherein the means co-operable with the ferrule comprises a base part co-operable with the base of the ferrule to locate the ferrule and securable to the casting surface.
3. A prop anchor according to claim 2, wherein the void former is fitted to the base 15 part.
4. A prop anchor according to claim 2 or claim 3, wherein the base of the ferrule is of non-circular periphery and the base part co-operates with the periphery of the ferrule base to thereby hold the ferrule against rotation on the casting surface. 20
5. A prop anchor according to any one of claims 2 to 4, wherein the base part includes a tube to fit over an upper part of the ferrule and the tubular void former is fitted to the tube of the base part to form an extension thereof. 25
6. A prop anchor according to any one of claims 1 to 5, wherein the base of the ferrule has a sufficient surface area to provide anchorage within the slab without the necessity of tying the ferrule to reinforcement.
7. A prop anchor according to any one of claims 1 to 6 further comprising a threaded 30 rod or bar engageable with the ferrule by passage through the void, and a shouldered nut engageable with the exposed end of the threaded rod/bar, the nut having a tapered collar P.\QPER\RSH\3()327462-CAP.doc«6rtW/2007 -7- extending beneath the shoulder to fit between the rod/bar and opposed sides of a slot in a foot plate of a prop to be secured by the anchor.
8. An anchor according to claim 6, wherein the threaded bar is reinforcing bar having 5 a partial or continuous thread,
9. A prop anchor comprising an internally-threaded ferrule having a base to provide stable support for the ferrule when placed on a casting surface for a concrete slab, and a support/void former assembly co-operable with the ferrule and comprising a base part 10 securable to the casting surface to locate the ferrule on the casting surface and to hold the ferrule against rotation, the base part having a tube engageable over the ferrule, the assembly further comprising an extension tube fitted to the tube of the base part to form a void extending between the upper surface of a slab cast onto the casting surface and the ferrule, the void serving to receive a threaded rod or bar engageable with the ferrule and by 15 which the foot plate of a prop resting on the slab can be retained.
10. A prop anchor according to claim 9, wherein the extension tube is formed with markings along its length to facilitate cutting of the tube to a length corresponding to the depth of the slab to be cast. 20
11. A prop anchor according to claim 9 or claim 10 having a removable cap to close the upper end of the extension tube to prevent ingress of concrete during casting the slab.
12. A prop anchor according to any one of claims 9 to 11, wherein the ferrule is 25 designed for use with reinforcing bar having a partial or continuous thread, the thread of the reinforcing bar being engageable with the thread of the ferrule by passage through the void.
13. A prop anchor substantially as hereinbefore described with reference to the 30 accompanying drawings. ? \OPER\RSH\30327
14. A prop anchor according to any one of the preceding claims when installed within a cast slab, the base of the ferrule being at the base of the slab and having a surface area which provides an anchorage effect sufficient to retain the prop when the slab has cured to a predetermined strength less than its full strength.