NZ617663A - Formwork restraint - Google Patents

Abstract

A formwork restraint (10) for a reinforcement bar (12) in a concrete structure is disclosed. The formwork restraint includes a restraint portion (20) for receiving the reinforcement bar. The formwork restraint further includes a support portion (36) adapted to connect the restraint portion to a reinforcing formwork arrangement (14) to maintain a desirable relationship between the reinforcement bar and the reinforcing formwork arrangement. A formwork system and method of providing a concrete structure is also disclosed.

Description

FORMWORK RESTRAINT FIELD In one preferred arrangement, the present invention relates to a formwork restraint.

BACKGROUND TO THE INVENTION In the construction of buildings a concrete slab may be provided with a number of starter bars extending a suitable distance upwardly away from the concrete slab. The starter bars typically provide both a reference point and reinforcing for a further section built upwardly from the concrete slab.

When preparing a concrete slab, starter bars are typically either fixed in position with the use of wire ties before the concrete is poured. With wire, the process of wire tying involves positioning each starter bar and twisting and cutting the wire to form numerous ties to hold the starter bars in position. This process is particularly labour intensive and time consuming.

Other system of fixing starter bars include: (i) continuity systems where pre- bent bars are positioned to extend through a number of holes in a casing; and (ii) anchor systems where ends of the starter bars are pushed into anchors.

These systems tend only to be suitable for particular situations and can be complex and costly.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. The applicant makes no admission that any reference constitutes prior art - they are merely assertions by their authors and the applicant reserves the right to contest the accuracy, pertinency and domain of the cited documents. None of the documents or references constitute an admission that they form part of the common general knowledge in NZ or in any other country.

It is against this background and the problems and difficulties associated therewith that the present invention has been developed.

OBJECT OF THE INVENTION It is an object of the invention to address some of the foregoing problems or at least to provide the public with a useful choice.

SUMMARY OF THE INVENTION According to a first aspect of preferred embodiments herein described there is provided a formwork restraint for a reinforcement bar comprising: a restraint portion for receiving the reinforcement bar; and a support portion adapted to connect the restraint portion to a reinforcing formwork arrangement to maintain a desirable relationship between the reinforcement bar and the reinforcing formwork arrangement when the reinforcement bar is received by the restraint, wherein the support portion comprises at least three elongate arms being positioned and peripherally spaced between the restraint portion and the reinforcement formwork arrangement, wherein the elongate arms space the restraint portion from the restraint link arrangement and at least one of the arms having a clip for clipping the corresponding arm to a bar of the restraint link arrangement.

Preferably the support portion comprises a spacer for spacing the restraint portion at least a predetermined distance laterally away from the reinforcing formwork arrangement. The reinforcement bar may comprise a starter bar and the reinforcing formwork arrangement may comprises a trench mesh.

In one preferred arrangement the support portion comprises three elongate arms each having a clip for clipping the corresponding arm to a bar of the reinforcing formwork arrangement. In another preferred arrangement the support portion comprises a securing portion having a first slot adapted to receive and hold at least two substantially parallel bars of the reinforcing formwork arrangement.

Particularly preferred arrangements of the present invention provide an advantageously convenient and labour saving alternative to having to wire tie each starter bar to a trench mesh in a formwork arrangement. Having to provide numerous wire ties in such a system is often labour intensive or otherwise problematic.

According to a second aspect of the preferred embodiments herein described there is provided a formwork system for maintaining the position of a plurality of starter bars relative to a reinforcing mesh structure, the system comprising: a plurality of starter bar holders each having a first portion for receiving a respective starter bar and a second portion extending therefrom for connecting the respective starter bar to the reinforcing mesh structure; wherein the first portions and the second portions of the starter bar holders are adapted to maintain the starter bars and reinforcing mesh structure in a desirable relative position.

Preferably the formwork system includes spacer elements for spacing base portions of the starter bars above the ground such that in use the base portions of the starter bar holders restrain movement of the starter bars relative to the reinforcing mesh structure at positions spaced away from the reinforcing mesh structure According to a third aspect of preferred embodiments herein described there is provided a formwork holder comprising: a first portion for receiving an elongate formwork element; and a second portion extending from the first portion for engaging a planar formwork arrangement to hold the elongate formwork element and planar formwork arrangement in relative position when the formwork element is received by the first portion.

According to a fourth aspect of preferred embodiments herein described there is provided a formwork restraint for a plurality of starter bars comprising: a body having a plurality of connection elements spaced therealong; the connection elements each defining an opening for receiving a corresponding starter bar.

According to a fifth aspect of preferred embodiments herein described there is provided a method of providing a reinforced concrete structure, the method comprising: providing a plurality of starter bars; a reinforcing mesh structure and a plurality offormwork restraints; and coupling first portions and second portions of the formwork restraints with the starter bars and reinforcing mesh structure respectively; wherein the first portions are positioned to restrain relative movement of the starter bars and the reinforcing mesh structure.

According to a sixth aspect of the preferred embodiments herein described there is provided a support for a starter bar system comprising: a first member and a second member, with a third member therebetween; wherein the first and second members are adapted to support a mesh above the ground and the third member is adapted to support a starter bar.

According to a seventh aspect of the preferred embodiments herein described there is provided a formwork restraint adapted to be positioned on a starter bar to engage horizontally extending formwork bars therebelow.

Preferred embodiments of the present invention are considered to provide a number of advantageous systems and methods including: (i) A formwork restraint that holds a starter bar in a vertical position during a concrete pour; (ii) A formwork restraint that allows a starter bar to be inserted through a hole in a holder and for lower clips to be clipped onto a trench mesh to provide a relatively stable cradle during a concrete pour; (iii) A formwork restraint that restrains a starter bar an advantageous distance above a trench mesh and which then extends downwardly to support a number of parallel bars of the trench mesh in a single slot; (iv) A formwork restraint that holds starter bars at relatively equal spacings during a concrete pour; and (v) A formwork restraint system that allows for the ready placement and alignment of starter bars relative to a trench mesh where each starter bar is relatively positioned at three locations.

It is to be recognised that other preferred forms and preferred advantages of the present invention will be apparent from the drawings and detailed description, along with the claims provided herebelow.

BRIEF DESCRIPTION OF DRAWINGS In order to facilitate a better understanding of the present invention, several preferred embodiments of the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a formwork restraint according to a first preferred embodiment of the present invention; Figure 2 is a perspective view of the formwork restraint shown in Figure 1, with the formwork restraint fitted to a starter bar and a trench mesh; Figure 3 is a perspective view of a formwork system according to a second preferred embodiment of the present invention; Figure 4 is a top view of a formwork restraint according to a third preferred embodiment of the present invention, the formwork restraint of Figure 4 also being shown in Figure 3; Figure 5 is a side view of a formwork restraint according to a fourth preferred embodiment of the present invention; Figure 6 is a fop view of the formwork restraint shown in Figure 5; and Figure 7 is an illustrative view of a method according to a fifth preferred embodiment of the present invention; Figure 8 is a perspective view of a formwork restraint according to a further preferred embodiment; and Figures 9 to 11 are engineering drawings showing possible measurements and relatively sizings of several of the preferred embodiments.

DETAILED DESCRIPTION OF THE DRAWINGS Referring to Figure 1 there is illustrated a formwork restraint 10 according to a first preferred embodiment of the present invention. The formwork restraint 10 is further illustrated in Figure 2 as advantageously maintaining a desirable relationship between a reinforcement bar 12 and a reinforcing formwork arrangement 14. In the embodiment, the reinforcement bar 12 is provided as a starter bar 16 and the reinforcing formwork arrangement 14 is provided as a trench mesh 18.

The formwork restraint 10 includes a restraint portion 20 for receiving the starter bar 16. The restraint portion 20 comprises a body 24 having a top portion 26 and a lower portion 28. The top portion 26 is reduced in diameter in comparison to the lower portion 28. The top portion 26 has an outer diameter of 40mm and an inner diameter of 12mm. The inner diameter of 12mm is defined by a passage 27 that extends through the body 24. The passage 27 is adapted to receive the starter bar 16 which has a diameter of about 11mm. In order to accommodate starter bars of a different diameter a narrower passage 27 may be used. Other forms of restraint portion 20 are envisaged.

The formwork restraint 10 includes a support portion 36 that is adapted to connect the restraint portion 20 to the mesh .18, as shown in Figure 2. The mesh 18, in this embodiment, is provided as a series of overlay ed reinforcement bars 38 that are welded together and supported on spacers (not shown) disposed on the ground. The mesh 18 is provided as an integral welded mesh that is manufactured as a sheet.

The support portion 36 of the formwork restraint 10 comprises three arms 40 including a first arm 42, a second arm 44 and a third arm 46. Each of the three arms 40 is formed from flexible plastics material. The restraint portion and support portion 36 are formed in one piece and are able to advantageously withstand the pressure of a concrete pour.

Each of the arms 42, 44, 46 includes a releasable connector 48 for connecting each of the corresponding arms to the mesh 18. Each releasable connector 48 is provided in the form of a clip 50 having an internal diameter of 11mm to firmly engage and connect with the bars of the mesh 18. As indicated above, the restraint portion 20, and the arms 42, 44 ,46 (including the releasable connectors 48) are integrally formed in one piece. This advantageously assists with ensuring that the formwork restraint 10 is able to withstand the pressure of a concrete pour, when connected to the starter bar 16 and mesh 18.

In this embodiment, each of the arms 42, 44, 46 are of the same fixed length and connect to the mesh structure 18 at similarly spaced locations 56, 58, 62.

Other embodiments may have arms of different length and be suited to different circumstances. As shown in Figure 2, the arm 42 engages a first bar 64, the arm 44 engages a second bar 66 and the arm 46 engages an intermediate bar 68 therebetween.

In operation a person constructing the formwork connects the clips 50 to the bars 64, 66, 68. The length of the three arms 40 ensures that they are suitably positioned. The three arms 40, by their resilient nature, ensure that support portion 36 provides a spacer that serves to space the restraint portion at least a predetermined distance 69 laterally away from reinforcing mesh structure 18. It is presently preferred that the length of each of the arms 42, 44 and 46 is between about 250mm and 400mm and that the distance 69 is between 350mm and 400mm. In the present embodiment the length of the arms 42, 44 and 46 is about 330mm. Other lengths are of course possible.

By spacing the the restraint portion 20 away from the mesh structure 18, using the arms 40, the formwork restraint 10 is able to advantageously maintain the alignment of the reinforcement bar 12 during a concrete pour. The three elongate arms 42, 44 and 46 and the restraint portion 20 accordingly maintain a desirable relationship between the starter bar 16 and the mesh 18, when the starter bar 16 is received in the restraint portion 20 as shown in Figure 2. In this embodiment the lower bend 67 of starter bar 16 is supported by a trench chair (not shown).

When laying a foundation in a trench, the use of a number offormwork restraints 10 is considered to be particularly advantageous to improve the formwork alignment and provide significant labour savings. This is especially the case in comparison to conventional techniques including those using thin wire to tie the starter bar 16 to the mesh 18 to hold the mesh 18 in position above the ground. Depending upon the circumstances, with the use of a number offormwork restraints 10, it may be possible to ' support the mesh 18 from the starter bar 16, without having to use spacers to directly support the mesh 18 from the ground.

Referring to Figure 3 there is shown a formwork system 70 according to a second preferred embodiment of the present invention. The formwork system 70 advantageously maintains the position of a plurality of starter bars 72 relative to a reinforcing mesh structure 74. The formwork system 70 is used to provide a reinforced concrete foundation in an elongate trench 76.

The system includes starter bar holders 78 each having a first portion 82 for receiving a corresponding one of the starter bars 72 and a second portion 84 that extends therefrom for connecting the corresponding starter bar 72 to the reinforcing mesh structure 74. The first portions 82 and the second portions 84 of the starter bar holders 78 are adapted to maintain the starter bars 72 and the reinforcing mesh structure 74 in a desirable aligned relationship as shown in Figure 3.

The starter bars 72 are provided as right angled starter bars having horizontally extending base portions 86. In the formwork system 70, the base portions 86 of the starter bars 72 are supported by spacers (not shown) that are positioned on the ground on the bottom of the trench 76. Relative to the mesh structure 74, the starter bars 72 are restrained by the spacers (not shown) and the first portions 82 of the starter bar holders 78. The first portions 82 restrain the starter bars 72 at positions spaced away from the mesh structure 74.

The formwork system 70 includes at least one formwork restraint 94. The formwork restraint 94 forms a further preferred embodiment of the present invention and is further illustrated in Figure 4. The formwork restraint 94 is advantageously adapted to hold four starter bars as shown in Figure 3. The formwork restraint 94 comprises an elongate body 96 having four connection elements 98 spaced at regular intervals along the elongate body 96.The connection elements 98 each define an opening 100 that is adapted for receiving a starter bar. In the formwork system 70 the formwork restraint 94 is used to assist with maintaining the spacing of the starter bars 72 at regular intervals of about 400mm. The arrangement of Figure 4 is considered to be advantageous.

Referring to Figure 5 there is shown a formwork restraint 110 according to a fourth preferred embodiment of the present invention. The formwork restraint 110 advantageously supports a right angled starter bar 112.

In the embodiment, there is provided a restraint portion 114 and a support portion 116. As shown in Figure 6, the restraint portion 1 14 defines a passage 118 for receiving the starter bar 112. The walls of the passage 118 allow for the restraint portion 1 14 to be moved laterally over starter bar 112, as opposed to having to be threaded therealong. This is considered to be advantageous.

The support portion 116 is advantageously adapted to connect the restraint portion 114 and the starter bar 112 to a formwork structure 120 to maintain alignment between the starter bar 112 and the formwork structure 120.

As shown in Figure 6, the support portion 116 comprises a first securing portion 122 and second securing portion 124. The securing portions 122,124 both include an extending portion 126 and an elongate U shaped slot 128.

Each extending portion 126 extends outwardly and downwardly away from the restraint portion 114 and bends to extend into each corresponding U shaped slot portion 128. The form and arrangement of the first and second securing portions 122, 124 is shown in Figures 5 and 6. The first and second securing portions 122, 124 form a V shaped section 130 (Figure 6) and a C shaped section 132 (Figure 5). Each U shaped slot 128 includes a closed end 134 and an open end 136. Between the closed ends 134 and the open ends 136 each U shaped slot 128 includes an upper elongate member 138 and a lower elongate member 140 which defines a securing slot 142 therebetween.

Each of the first and second securing portions 122, 124 include an a closure portion 144 at their corresponding open ends 136 on their lower elongate members 140. The closure portions 144 are moveable between an open and closed condition to allow three substantially parallel bars 146 of the mesh structure 120 to be received in and extend between the two securing slots 140. Both slots 128 engage both sides of the bars 146.

The first and second securing portions 122, 124 operate to hold the three bars 146 during a concrete pour. Movement of the bars 146 within the slots 120 is restrained by the closed end 134 and the closure portions 144. The closure portions 144 are biased towards a closed condition by virtue of the lower elongate members 138 being made from resilient plastics material.

Figures 5 and 6 also illustrate a support 150 according to a further preferred embodiment of the present invention. The support 150 includes a first member 154 and a second member 156 connected by a third member 158.

The third member 158 is adapted to support the starter bar 112 below the three bars 146 that extend over the starter bar 1 12. The three bars 146 are supported by the first member 184 and the second member 186 with the third member 158 providing a holder 160 for the starter bar 112. In this embodiment the holder 160 comprises a depression 162 shaped to receive the starter bar 112. The support 150 is considered to be advantageous for the reasons that it can support a trench mesh and starter bar at one location.

Referring to Figure 7 there is shown a method 170 of providing a reinforced concrete structure, according to another embodiment of the present invention. At block 172 the method comprises providing a plurality of starter bars 174, a mesh 176, a plurality offormwork restraints 178 and a plurality of spacers 180. At block 182 the starter bars 174 are placed underneath the mesh 176 within a trench. This serves to hold the mesh 176 in place.

Concrete is then poured into the trench. At block 184, once the required amount of concrete has been poured, another mesh layer is positioned and another layer of concrete is poured. In the method 170, the starter bars 174 are fixed in position using the spacers 180 to hold the right angled base portions of starter bars 174 above the ground. The starter bars 174 are positioned relative to the mesh 176 using the formwork restraints 178 and are regularly spaced using further formwork restraints 186. Advantageously the starter bars 174 are fixed by being held at three locations. This is considered to be beneficial in withstanding the pressure applied by the concrete as it is poured into the trench.

Referring to Figure 8 there is shown a further embodiment in the form of a formwork restraint 200. The formwork restraint 200 includes a connector 202 for attaching to formwork bars 204. The connector 202 includes a first connector 206 provided as a pair of snap connectors 208 as well as a second connector 210 provided as a par of snap connectors 212. The first connector 206 is arranged to snap onto a formwork bar 214. The second connector 210 is arranged to snap onto a formwork bar 216. As shown the releasable connector 202 is adapted to snap to the formwork bar 214 and the formwork bar 216 so as to span four formwork bars 204. This is considered to provide the formwork restraint 200 with advantageous stability.

The formwork restraint 200 advantageously comprises a single unitary body 218 formed from plastics material, where the body 218 is formed in a single mould. The releasable connector 202 is provided by a base portion 220 for supporting an extension 222 for assisting with maintaining an L-shaped starter bar 224 in an upright condition 226.

In this embodiment the extension 222 provides an upper portion 228 through which the upright portion 232 of the starter bar 224 can extend. The upper portion 228 extends upwardly from the base portion 220 and is advantageously configured to limit movement of the upright portion 232 of the starter bard 224 to the extent of a channel 236 provided by the upper portion 228.

The base potion 220 advantageously provides a lower portion 238 through which a horizontal portion 240 of the starter bar 224 can extend. The lower portion 238 is advantageously configured to limit movement of the portion 240 to movement within a channel 242. The channels 236 and 242 provide openings within the body 218 for restraining the starter bar 224.

In order to fix the formwork restraint 220 in position, the formwork restraint 220 is slid down the portion 232 of the starter bar 224 to engage the formwork bars 204 and receive and restrain the horizontal portion 240 of the starter bar 224.

Figures 9 to 1 1 provide engineering drawings showing measurements and dimensions and relative sizing of components of several of the preferred embodiments described above. Other embodiments, sizings and so forth are, of course possible.

It will be recognised that the embodiments described, as shown in the accompanying drawings, provide a number of advantages including: (I) The ability to maintain a desirable relationship between a starter bar and a mesh in a formwork system where the starter bar is restrained a predetermined distance away from the mesh. (ii) The ability to support both a starter bar and mesh in relative position for a concrete pour in a trench mesh environment, where the starter bars are spaced at regular intervals along the mesh. (iii) A method of readily positioning starter bars relative to a mesh in a trench where the starter bars are restrained at a first location with respect to the mesh, a further location above the mesh, and a further location below the mesh.

It is to be recognised that various alterations and equivalent forms may be provided without departing from the spirit and scope of the present invention.

This includes modifications within the scope of the appended claims along with all modifications, alternative constructions and equivalents.

In the present specification, the presence of particular features does not preclude the existence of further features. The words "comprising", "including" and "having" are to be construed in an inclusive rather than an exclusive sense.

THE

Claims (9)

CLAIMS 1. DEFINING THE INVENTION ARE AS FOLLOWS :

1. A formwork restraint for a reinforcement bar comprising: a restraint portion for receiving the reinforcement bar; and a support portion adapted to connect the restraint portion to a reinforcing formwork arrangement to maintain a desirable relationship between the reinforcement bar and the reinforcing formwork arrangement when the reinforcement bar is received by the restraint; wherein the support portion comprises at least three elongate arms being positioned and peripherally spaced between the restraint portion and the reinforcement formwork arrangement; wherein the elongate arms space the restraint portion from the restraint link arrangement and at least one of the arms having a clip for clipping the corresponding arm to a bar of the restraint link arrangement.

2. A formwork restraint as claimed in claim 1 wherein the support portion comprises a spacer for spacing the restraint portion at least a predetermined distance laterally away from the reinforcing formwork arrangement.

3. A formwork restraint as claimed in claim 1 or 2 wherein the support portion comprises a releasable connector for connecting the restraint portion to the reinforcing formwork arrangement.

4. Aformwork restraint as claimed in any one of claims 1 to 3 wherein the three elongate arms each having a clip for clipping the corresponding arm to a bar of the reinforcing formwork arrangement.

5. A formwork restraint as claimed in any one of claims 1 to 3 wherein the support portion comprises a securing portion having a first slot adapted to receive and hold at least two substantially parallel bars of the reinforcing formwork arrangement in the first slot.

6. A formwork restraint as claimed in claim 5 wherein the securing portion comprises a second slot spaced apart from the first slot such that the first and second slots are both adapted for receiving and holding the at least two substantially parallel bars of the formwork arrangement either side of the reinforcement bar when the reinforcement bar is received by the restraint.

7. A formwork restraint as claimed in claim 5 or 6 wherein the securing portion is biased toward maintaining the or each slot in a closed condition for preventing movement of the at least two substantially parallel bars of the reinforcing formwork out of the slot.

8. A formwork restraint as claimed in any one of claims 5 to 7 wherein the securing portion includes a closure that is moveable between a first condition and a second condition, at an open end of the or each slot.

9. A formwork restraint substantially as herein described with reference to the accompanying drawings.