GB2129029A

GB2129029A - Fixing devices

Info

Publication number: GB2129029A
Application number: GB08327637A
Authority: GB
Inventors: Howard Peter John Taylor
Original assignee: Dow Mac Concrete Ltd
Current assignee: Dow Mac Concrete Ltd
Priority date: 1982-10-19
Filing date: 1983-10-14
Publication date: 1984-05-10
Also published as: DK481283D0; BE898015A; DK481283A; NL8303493A; FR2534614A1; DE3337737A1; IT1169583B; IT8323336A0; GB8327637D0

Abstract

A method of securing a fixing device in a cast concrete member includes wrapping a bar (14) in a split rubber sleeve (16) locating the sleeve and bar in a desired location and casting the concrete around the bar and the sleeve. When the concrete is sufficiently cured the sleeve is flexed and removed leaving a portion of the bar exposed for fixing articles thereto. The bar may have attachments to a second bar to form a 'ladder' so that one stile is embedded in the concrete. The wire 14 may have shoulders or a screw-thread to prevent a hook or other attachment means from slipping along the bar. <IMAGE>

Description

SPECIFICATION Fixing devices This invention relates to fixing devices for use with concrete articles and to concrete articles incorporating such devices.

Once a concrete article has been produced, whether reinforced or otherwise, it is notoriously difficult to secure items to that concrete article because of the inherent characteristics of concrete. To overcome this long-standing problem, particularly in the industrial sphere, provision has been made at the time of manufacture of the concrete article, such as a beam, floor unit, or a column, to enable the ready fixing of items at a variety of different locations once the concrete article is in situ or possibly beforehand. One such proposal involves the incorporation of a dovetail section channel member of galvanised metal which is filled initially with a plastics material such as foamed polystyrene to prevent the channel becoming filled with concrete during manufacture of the concrete article.To secure any given item after installation special anchorages are used which by turning through 900 become firmly anchored in the dovetail section channel. To ensure firm anchorage of the channel itself tags are provided at intervals along the base of the dovetail section channel but the overall cost of this arrangement including the necessity for special anchorage bolts is high, particularly bearing in mind that much of the channel remains unused throughout its life.

Another solution to the problem involves the incorporation of a generally square section channel of galvanized steel which has pairs of elongate slots at its base distributed along the length, each pair of slots having between them an outwardly deformed section which enables the channel to be adequately keyed to the concrete with the aid of tags inserted in the slots. Again special connectors for securing items in the channel are necessary and these tend to increase the cost of manufacture and assembly. Both forms of channel may be used in very short lengths, if appropriate, to provide limited freedom of adjustment with respect to a precise fixing location on another member.

The channel members are particularly useful with brick ties or with the fixing devices of external cladding.

Other forms of fixing are also known but they are inherently less satisfactory than the pre-prepared channels since they necessitate substantial in situ operations on every occasion when an item is to be fixed to a concrete member.

According to the present invention there is provided an assembly of a concrete member and a fixing device, said assembly comprising a channel in the concrete and an elongate metal member located in the channel and spaced from the longitudinal walls thereof, but having portions thereof embedded in the concrete as to enable a load to be accommodated, the fixing device engaging the elongate metal member at a desired location on a non-embedded portion thereof.

Further according to the present invention there is provided a method of manufacturing an assembly of a concrete member and a fixing device, said method comprising the steps of locating an elongate metal member in a mould together with an elastically resilient sleeve fitted around a part of the elongate metal member and having an external form of required size and shape to define a channel in the concrete, casting concrete around the sleeve and parts of the metal member not covered by the sleeve so that one surface of the sleeve substantially coincides with the local surface of the concrete member, and, after the concrete has cured, removing the sleeve thereby leaving the elongate metal member partly embedded in the concrete and partly exposed in the channel which has been formed by the sleeve.

The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a fragmentary cross-section illustrating the method in accordance with the invention as applied to a first embodiment of an assembly of a concrete member and a fixing device; Figure 2 is a fragmentary section illustrating a second embodiment of the assembly after the method has been completed; Figure 3 is a longitudinal, horizontal, section, to a reduced scale, illustrating the first embodiment of the assembly when incorporated in a concrete member; Figure 4 is a longitudinal, horizontal, section to a reduced scale illustrating the second assembly in accordance with the invention; Figure 5 is a fragmentary section illustrating a modification of the assemblies of Figures 2, 3 or 4;; Figure 6 is a longitudinal, vertical, section illustrating a further modification which can be applied to the first or to the second embodiment or to the modification of Figure 5; and Figure 7 is a longitudinal, vertical section of a still further modification which can be applied to the first or to the second embodiment or to the modification of Figure 5.

The method in accordance with the invention will now be described in greater detail with reference to Figures 1 and 2.

When a concrete article 10 incorporating a fixing device 12 is to be manufactured, an elongate metal wire member or bar 14 of circular section has mounted thereon a rubber (or other elastically resilient material) sleeve member 1 6 of substantially semi-annular or U-section having an internai cross-section complementary to the external section of the wire member 14, this rubber member being provided with a cut 18 so that it can be readily withdrawn from its location on the elongate wire member 14. The cut 18 will be as narrow as possible, consistent with ease of removal and to avoid ingress of wet concrete mix.

The assembly of wire member 14 and rubber sleeve member is then mounted in position within a mould and the plane face of the rubber member is made to lie in the required surface corresponding to the surface of the completed concrete article 10 to which items are to be fixed.

The member 14 may be secured in the mould by bracing, spacing the rubber from reinforcement rods or risers or it may be secured through the relevant mould face. If the latter means of securing is adopted, nails may be used which pass through the rubber from the inside outwardly into the mould. Alternatively, bolts may be used with the head disposed internally and a nut externally at the mould face. The heads of the bolts will be accommodated in countersunk recesses of the rubber.

The concrete article is then cast conventionally and after the curing has been completed to an adequate degree, the rubber member is fixed and removed leaving the metal wire member 14 securely in position with portions 14' or 20 embedded in the concrete of the concrete member 10. This feature is particularly clearly shown in Figures 3 and 4. The rubber member 16 can be reused on many occasions before deterioration sets in. The channel formed by the rubber member, will, of course, correspond in crosssection and length to the shape of the rubber member.

The rubber sleeve member will have a length dimension corresponding to the required length of wire member for fixing purposes and the ends will be chamfered as best shown at 22 in Figures 3 and 4.

The chamfered ends of the rubber sleeve may be used as an aid when removing the sleeve from the cured concrete article. At the stripping stage a corner of the sleeve is lifted with a screwdriver and the corner gripped with pliers. The stripping can then be readily progressed.

In the construction of Figures 2 and 4 the wire member 14' has the other 'stile' 24 embedded in the concrete member defining the base of this channel but this extends parallel to the member which actually accommodates one end of a hook member 26 or other fixing device such as shown in Figure 2. It will be understood that once the hook member 26 is in situ a force will normally be applied to it so that there is no freedom of movement. To take into account the possibility that there may be some freedom of movement an appropriately shaped plastics plug 28 can be used as illustrated in Figure 6. As seen in this Figure the hook member may be screw threaded so that it can act to support a hanger for pipes or other services.

In another modification, illustrated in Figure 1, the rubber sleeve 1 6 has cast-in ferrules 30 which will assist handling and location in the mould.

Such ferrules 30 will be spaced at regular intervals and have tapped bores to receive bolts from the outside which pass through apertures in the mould wall. Such apertures will be matched to the spacing of the ferrules by a template. By this modification the rubber will be automatically stripped from the concrete article at the de-moulding stage. If the ferrules do not receive bolts at the pre-casting stage, then they can be applied subsequently to assist removal of the rubber sleeve.

The bar 14' of Figure 3 will normally be used where a comparatively long length is required, whereas the bar 14 will be used for shorter lengths. For both fixings the wire or bar will be protected by galvanizing or by a plastics coating or even be made of stainless steel. Where the ladder fixing 14' is used the rubber sleeve 1 6 will be suitably modified to accommodate the crosspieces.

The fixing devices may form part of the reinforcement of the concrete article 10 or be secured thereto.

The two embodiments and the modification of Figures 1 and 5 are intended for incorporation in concrete articles so that the rod 14 is at any desired orientation. However, when inclined with respect to the horizontal and in particular when vertical, it will normally be desirable to employ either of the modifications of Figures 6 and 7. In Figure 6 at least the exposed portion of each bar 14 or 14' is provided with a series of spaced shoulders 32 so that a hooked member such as 26 cannot slip along the bar while items to be mounted are secured to the free end portion of the member. The shoulders 32 may extend along the whole length of the bar 14 since they will improve keying in the concrete of the embedded portions.

In the modification of Figure 7, the bar 14 or 14' is screw-threaded at least along the exposed portion for the same purpose as in the modification of Figure 6. The friction provided by the turns of the thread will normally be sufficient to prevent sliding of the hook 26, but for greater security the corresponding contact surface of the hook may also be screw-threaded.

It will be readily apparent that the method and the constructional parts required are very simple but effective in practice and extremely economical in relation to the known devices which serve the same purpose.

Claims

1. An assembly of a concrete member and a fixing device, said assembly comprising a channel in the concrete and an elongate metal member located in the channel and spaced from the longitudinal wall thereof, but having portions thereof embedded in the concrete so as to enable a load to be accommodated, the fixing device engaging the elongate metal member at a desired location on a non-embedded portion thereof.

2. An assembly according to claim 1, wherein end portions of the elongate metal member are embedded in the concrete defining longitudinal ends of the channel.

3. An assembly according to claim 1 or claim 2, wherein the elongate member is secured at intervals along its length to a second elongate metal member, the said second member being embedded in concrete defining the base of the channel.

4. An assembly according to any one of claims 1 to 3, wherein the fixing device is hooked to engage the elongate metal member.

5. An assembly according to any one of the preceding claims wherein a plastics plug engages in the channel to retain the fixing device in position.

6. An assembly according to any one of the preceding claims, wherein the channel is of U-section and the elongate metal member is a steel bar of circular section.

7. An assembly according to any one of the preceding claims wherein the elongate metal member has abutment means spaced along at least the non-embedded portion thereof.

8. An assembly according to any one of claims 1 to 6 wherein the elongate metal member is screw-threaded at least over the length of the non-embedded portion thereof whereby to increase frictional contact with the fixing device.

9. A method of manufacturing an assembly of a concrete member and a fixing device, said method comprising the steps of locating an elongate metal member in a mould together with an elastically resilient sleeve fitted around a part of the elongate metal member and having an external form of required size and shape to define a channel in the concrete, casting concrete around the sleeve and parts of the metal member not covered by the sleeve so that one surface of the sleeve substantially coincides with the local surface of the concrete member, and, after the concrete has cured, removing the sleeve thereby leaving the elongate metal member partly embedded in the concrete and partly exposed in the channel which has been formed by the sleeve.

10. A method according to claim 9, wherein the sleeve is slit longitudinally to facilitate removal after the concrete has cured.

1 A method according to claim 9 or claim 10, wherein end portions of the elongate member are embedded in the concrete.

12. A method according to claim 9 or claim 10, wherein the elongate member is secured to a second, parallel, elongate member and the second member is embedded in the concrete.

13. A method according to any one of claims 9 to 1 2 wherein the sleeve is provided in its surface corresponding substantially to the local surface of the concrete with internally-threaded ferrules or bushes, the method further comprising engaging screws or bolts in respective ferrules and gripping the heads of the screws or bolts after curing to enable removal of the sleeve.

14. A method according to any one of claims 9 to 12, wherein the sleeve is provided in its surface corresponding substantially to the local surface of the concrete with internally threaded ferrules or bushes, the method further comprising engaging screws or bolts in respective ferrules prior to pouring the concrete and with the screw or bolt heads on the outside of the mould so that after curing de-moulding takes place with automatic removal of the sleeve from the channel formed thereby.

1 5. A system for providing at least one fixing point in a surface portion of a concrete article, said system comprising the provision of an elongate metal member, closing one portion of the metal member in a flexible sleeve with other portions of the metal member projecting from the sleeve, inserting the metal member and sleeve assembly in a mould, pouring concrete into the mould and, after the concrete has cured sufficiently, removing the flexible sleeve whereby to leave a portion of the elongate metal member exposed in a recess in the concrete defined by the sleeve while the said other portions of the elongate metal member initially exposed are embedded in the concrete of the article, the exposed portion serving to retain a fixing device.

1 6. A system according to claim 1 5 wherein said other portions are end portions of the elongate metal member and are embedded in the concrete.

1 7. An assembly according to claim 1 5 wherein the elongate metal member includes a further elongate metal member connected thereto by transverse members the further member and transverse member constituting said other portions and are embedded in the concrete.

1 8. A system according to any one of claims 1 5 to 1 7 wherein the fixing device is of hooked form which engages the exposed portion of the elongate metal member as incorporated in the concrete article.

1 9. A system according to claim 18 is further comprising a plastics plug engaging at least a part of the recess in the cured concrete defined by the flexible sleeve and serving to assist retention of the fixing device.

20. A system according to any one of claims 1 5 to 19, wherein the recess in the concrete article is of U-section and the elongate metal member includes a steel bar of circular section.

21. A system according to any one of claims 15 to 20 wherein the elongate metal member is screw-threaded at least over the length of the non-embedded portion thereof whereby to increase frictional contact with the fixing device.

22. A system according to any one of claims 1 5 to 20 wherein the flexible sleeve is provided with screw threaded ferrules or bushes and the system further comprising engaging screws or bolts in the ferrules to facilitate removal thereof after the concrete has cured.

23. An assembly of a concrete member and a fixing device substantially as hereinbefore described with reference to the accompanying drawings.

24. A method of manufacturing an assembly of a concrete member and a fixing device substantially as hereinbefore described with reference to the accompanying drawings.