EP0869227A2

EP0869227A2 - Concrete reinforcing structures

Info

Publication number: EP0869227A2
Application number: EP98302544A
Authority: EP
Inventors: Stephen Render
Original assignee: Gray Engineering Ltd
Current assignee: Gray Engineering Ltd
Priority date: 1997-04-02
Filing date: 1998-04-01
Publication date: 1998-10-07
Also published as: GB9706722D0; GB2323864A; EP0869227A3

Abstract

A structural element adapted to be incorporated in a reinforcement cage for a diaphragm wall, and incorporating means for attachment of a plurality of reinforcing members of the cage to the element at positions spaced from one another.

Description

This invention relates to structures of reinforcing members for reinforcing concrete. Specifically it relates to the construction of a "cage" of reinforcing members for use in making a reinforced-concrete diaphragm wall.

Structures, commonly known as cages, of reinforcing bars for reinforcing concrete diaphragm walls are usually manufactured on site by welding at least the main reinforcing bars together. Typically a cage comprises longitudinal and transverse main reinforcing bars, which may be welded to one another, and further reinforcing bars which may be held to the main reinforcing bars in the required position and orientation by use of binding wire.

Such cage construction is inconvenient, and accordingly it is a broad object of the present invention to facilitate cage construction on site.

According to one aspect of the present invention, we provide a structural element adapted to be incorporated in a reinforcement cage for a diaphragm wall, and incorporating means for attachment of a plurality of reinforcing members of the cage to the element at positions spaced from one another.

Preferably the means for attachment of reinforcing members to the structural element comprises clamping means. Such clamping means may comprise U-bolts secured to the structural element and each able to receive a reinforcing member or members between its limbs and have such member or members engaged by a bridging piece between said limbs, there being nuts on free end portions of the limbs to bear against the bridging piece and, when tightened, to clamp the reinforcing member or members by the bridging piece.

Alternatively the clamping means may comprise clamps generally of a type which is well known for use in scaffolding structures, comprising a base portion, and a clamping portion movable, e.g. pivotable, relative to the base and defining with the base a formation for reception of a reinforcing member or members, and fastening means operable between the base portion and clamping portion to effect relative movement therebetween and apply a clamping force to the reinforcing member or members held therebetween.

The structural element conveniently comprises frame members each of which is in the form of a generally planar member bent from steel bar such as commonly is used as concrete reinforcement bar, in the form of at least part of a generally square or rectangular figure and two of such frame members being held in spaced parallel relationship to one another by support members extending therebetween.

The support members conveniently are also members of reinforcement bar material, each preferably being in the form of an elongate closed loop with its opposite ends welded to the frame members.

According to another aspect of the invention, we provide a reinforcement cage for a diaphragm wall, comprising at least one structural element according to the first aspect of the invention and a plurality of reinforcing members attached thereto.

Preferably the reinforcement cage comprises a plurality of structural elements as aforesaid, with reinforcing members extending longitudinally and laterally therebetween.

According to yet a further aspect of the invention, we provide a method of making a reinforcement cage for a diaphragm wall, comprising securing a plurality of reinforcing members to at least one structural element in accordance with the first aspect of the invention, by use of said attachment means of the element.

The invention will now be described by way of example with reference to the accompanying drawings, of which:-

Figure 1 is a perspective view of a structural element in accordance with the invention, showing the manner of its use in accordance with the invention;

Figure 2 is a diagrammatic elevation of a reinforcement cage for a diaphragm wall, with structural elements in accordance with the invention included therein.

Referring firstly to Figure 1 of the drawings, this shows in perspective view a structural element in accordance with the invention, and its method of use in accordance with the invention. The structural element comprises two frame members 10, 11, which are each formed of steel bar bent into a U-shaped configuration of substantially rectangular external envelope. The frame member 10 comprises

parallel limbs

12, 13 joined by a part 14 extending therebetween, the free ends of the

limbs

12, 13 terminating in

portions

15, 16 respectively bent back to extend parallel to the respective limbs: thus the free ends of the

limbs

12, 13 are themselves generally of U-shaped configuration. The frame member 11 is of the same shape as the frame member 10, and both members are substantially planar.

Instead of the illustrated generally U-shaped configuration, one or both of the frame members 10, 11 could be a closed loop of substantially rectangular configuration, with the free ends of the bar forming such a loop possibly welded to one another.

The frame members 10, 11 are secured to one another in spaced parallel relationship by a number of support members extending therebetween. One of such support members is indicated at 17 in Figure 1 and such support member comprises an elongate closed loop of steel bar made by bending a length of such bar into the closed loop and welding its ends together. The opposed ends of such a loop are welded to the respective frame members. As illustrated, there are a total of three such support members joining the limbs as 12, 13 of each of the frame members 10, 11, and four such loops joining the parts as 14 of the two frame members.

The structural element is provided with a total of eight attachment means for attaching reinforcing members thereto. The frame member 10 has two attachment means provided at the free ends of its

limbs

12, 13 and two where such limbs join the part 14, and the frame member 11 is similarly provided. Each of such attachment means provides for clamping of a reinforcement bar to secure it to the structural element, and as illustrated each of such attachment means comprises a U-bolt. The U-bolts on the frame member 10 are indicated at 20, 21, 22, 23 while the U-bolts on the frame member 11 are indicated at 24, 25, 26, 27. As most clearly seen for the U-bolt 26 on the frame member 11, a generally U-shaped spacer member 28 of bent steel bar is interposed between each U-bolt and its frame member so that the free ends of the limbs of each U-bolt are spaced sufficiently far from the frame member to be able to receive without inhibition a bridging member and nuts whereby the bridging member can be caused to clampingly engage a member placed between the limbs of the U-bolt. The U-bolts are secured to the frame members by fillet welding between the adjacent surfaces of the respective U-bolts, spacers and frame members.

As an alternative to the U-bolts above described, the structural element could be provided with attachment means each generally in the form of a clamping device such as is well known for use in scaffolding structures. Such a clamping device comprises a base portion which would be fixed to the structural element, and a clamping portion defining with the base portion a formation in which a reinforcing bar can be received, the clamping portion being able to be moved relative to the base portion by a fastening means to clamp the reinforcing bar in the formation.

It will be appreciated that more or fewer than the eight attachment means illustrated could be provided, in accordance with the number of reinforcing bars required to be thus secured to the structural element.

In Figure 1 of the drawings, a number of reinforcing bars are placed in assembled relation with the structural element. Five "bundles" each of three reinforcing bars are depicted at 30, 31, 32, 33, 34, and the

bundles

30, 34 are held and clamped in position in engagement with the U-bolts 23, 27 and 22, 26, respectively. Further reinforcing

bars

35, 36 extend transversely of the reinforcing bar bundles 30 to 34, and are held to the latter by wire ties as indicated at 37 in respect of the bundle 31 and bar 35. Other sizes or types of reinforcing bars or combinations thereof could be used as appropriate.

Parallel to the reinforcing bar bundles 30 to 34 there are individual reinforcing

bars

38, 39, 40, 41, 42 and of these the bar 38 is held by U-bolts 20, 24 and the bar 42 by U-bolts 21, 25, being held clamped in position by tightening of the nuts on the U-bolts. The bars 39 to 41 are held to the part 14 of frame member 10 and the corresponding part of frame member 11 by wire ties.

Alternatively clamping devices or other means could be provided for holding bars 39 to 41 and/or other reinforcing bars.

Figure 2 shows by way of example how a plurality of structural elements as shown in Figure 1 would be used in a complete cage structure for reinforcing a diaphragm wall. In Figure 2, part of such a cage structure is shown with an array of a total of twelve such structural elements arranged as an upper row 50 of three such elements and three such elements indicated at 51, 52, 53. There is a lowermost row 54 of three elements, and intermediate rows 55, 56 thereof. Vertically extending reinforcing bars or bundles thereof as 30 to 34 and 38 to 42 would be connected between the structural elements, some such bars or bundles extending the full height of the cage and some for part only of the height. There are also transverse reinforcement bars as 35, 36. The vertically and transversely extending bars would not only be provided where they are connected to the structural elements: they would also be provided in the spaces therebetween. It will be appreciated that other reinforcement bars, e.g. extending at an angle between parts of the complete cage would be provided in order to impart the cage a degree of rigidity against distortion when being handled. More or fewer structural elements could be provided, as required, in the cage.

It will be appreciated, however, that by use of structural elements in accordance with the invention, the reinforcement cage is provided with a basic structure which can be assembled on site without welding by use of the clamping devices provided on the structural elements.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

A structural element adapted to be incorporated in a reinforcement cage for a diaphragm wall, and incorporating means for attachment of a plurality of reinforcing members of the cage to the element at positions spaced from one another.
A structural element according to Claim 1 wherein said means for attachment of reinforcing members to the structural element comprises clamping means.
A structural element according to Claim 2 wherein said clamping means comprises U-bolts secured to the structural element, each U-bolt being able to receive a reinforcing member or members between its limbs and to have such member or members engaged by a bridging piece between said limbs, and nuts on free end portions of the limbs to bear against said bridging piece and for clamping the reinforcing member or members by the bridging piece.
A structural element according to Claim 2 wherein said clamping means comprises clamps each comprising a base portion, a clamping portion movable relative to the base, and defining with the base a formation for reception of a reinforcing member or members, and fastening means operable between the base portion and clamping portion to apply a clamping force to the reinforcing member or members held therebetween.
A structural element according to any one of the preceding claims comprising frame members each comprising a generally planar member of steel bar.
A structural element according to Claim 5 wherein each frame member is of generally square or rectangular configuration, two of said frame members being held in spaced parallel relationship to one another by support members extending therebetween.
A structural element according to Claim 5 or Claim 6 wherein each support member is in the form of an elongate closed loop having its opposite ends welded to the respective frame members.
A structural element according to any one of Claims 5 to 7 wherein said frame members and support members are of reinforcement bar material.
A reinforcement cage for a diaphragm wall, comprising at least one structural element according to any one of the preceding claims and a plurality of reinforcing members secured thereto.
A reinforcement cage according to Claim 9 and comprising a plurality of said structural elements, with reinforcing members extending longitudinally and laterally therebetween.
A reinforcement cage according to Claim 10, wherein at least some of said reinforcing members are secured to said structural elements by use of said attachment means of the structural elements.
A method of making a reinforcement cage for a diaphragm wall, comprising securing a plurality of reinforcing members to at least one structural element in accordance with any one of Claims 1 to 8, by use of said attachment means of said at least one structural element.