GB2076103A - Connections between concrete members - Google Patents

Abstract

The invention relates to prefabricated structures and more particularly to a method for securing together two concrete members 11, 12 in fixed relationship by forming keyways 13a in the two members and locking the members together with a key 21 entered into both keyways. In a preferred embodiment the keyway in each concrete member includes a metal liner 19, which may be secured as by welding to metal reinforcement in said member and thus, when the key is a metal member, the reinforcement in one concrete member can be connected to the reinforcement in the other member via metal members, whereby an extremely strong, rigid, and weather resistant connection of the two concrete members is obtained. <IMAGE>

Description

SPECIFICATION Improvements in or relating to prefabricated structures The present invention relates to prefabricated structures and has particular application to a method for securing together two concrete members in fixed relationship.

Prefabricated structures are well known in the building art and there are many known means for securing together the component units of the structure and thus, such units are frequently secured by metal fasteners, such as nut and bolt arrangements, and/or by the interlocking of elements of the units, and/or by grouting, in which latter case the structure is rendered substantially permanent.

A difficulty with conventional metal fasteners is that such fasteners are open to corrosion and the fasteners engage with the concrete, rather than any metal reinforcement in the concrete, so that the strength of such joints, with time, is always suspect.

As stated above it is well known to provide the units with interlocking elements the most common of which is a tongue and groove arrangement used, for example, when panels are to be supported between pillars and whereby said panels have their end regions engaged in recesses in the pillars. This system suffers from the disadvantages that as most concrete casting methods are relatively rough a substantial clearance is required for the interlocking parts and a "tight" securement of the interlocking parts cannot be obtained without the use of grouting, which renders the connection permanent. Further, the abutting faces of the interlocking elements are concrete faces and there is no inter-connection between metal reinforcements of the connected units.

The present invention seeks to provide a method of securing together two concrete members in fixed relationship and whereby a tight and accurate location of the two concrete members can be obtained and an inter-connection between metal reinforcements for the two concrete members can be achieved.

According to the present invention there is provided a method for securing together two concrete members in fixed relationship comprising the steps of forming a keyway in each member in such manner that the keyways in the two members register when said members are in desired relationship, and securing the members by slidably inserting a key in both keyways whereby the key bridges the junction of said members.

Preferably the method includes the steps of cutting the keyways in pre-formed members, conveniently by grinding, but most preferably the keyways are formed during the casting of the members.

Preferably the method includes the steps of lining each keyway with a sheet metal liner, hereinafter referred to as a "keyway liner", and in one method pre-formed liners are inserted into pre-formed keyways whilst in a more preferred method the pre-formed keyway liners are cast in said members.

When the two concrete members include metal reinforcements the method preferably includes the steps of securing the keyway liners to the reinforcements of the respective members, conveniently by welding.

Preferably the method includes the steps of forming each keyway to have surfaces facing away from the direction of the second member and extending in the length direction of the keyway, and providing co-operating surfaces on the key, extending in the length direction of the key, to prevent the key from being pulled out of the keyway other than in the length direction of the key.

Preferably the method includes the step of sealing the key in said keyways to prevent erosion of the key and, more preferably, sealing the key in the keyways with a mastics material and forcing mastics material into the junction between the two members to protect that part of the key bridging said members.

When one or the other or both of said concrete members comprises a plurality of concrete elements, each of which is to be attached to the other member, the method preferably includes the steps of forming a keyway in each concrete element such that said element keyways are in axial alignment when the said concrete elements are in the desired relationship with the other member, and inserting the key, or keys in end to end relationship, into the keyways so that the, or each, key extends across the junction of at least two more said elements.

The invention also envisages, in combination, two concrete members intended to be retained in fixed relationship by a key, each said member presenting a keyway open at that face of the member intended to be presented to the other member, and said keyways extending in parallel registered relationship to receive a key when said members are assembled in the desired relationship, and a key intended to be inserted longitudinally into said registered keyways.

Preferably each keyway is defined by a metal liner embedded in a recess in its respective member and, when a member includes a metal reinforcement, said metal liner is conveniently secured to said metal reinforcement.

Preferably the key and each keyway present cooperating abutment surfaces, inclined to the general plane of the key and arranged to prevent displacement of the key from the keyway other than in the length direction of the key.

The invention further envisages a combination of two concrete members in which one of said concrete members comprises a plurality of concrete elements, each of which is intended to be retained in fixed relationship with the other member, and wherein each concrete element includes a keyway and the keyways of all said elements are axially aligned when said elements are in their desired position relative to said other member and whereby a common key has one side edge region inserted into the keyway in said other member and its other side edge inserted into all the aligned element keyways.

Preferably the key comprises an elongate element, of uniform cross-section throughout its length, defined by a plate-like mid-region with enlarged side edge regions. Each enlarged side edge region may be of circular, triangular, rectangular or any other configuration, conveniently presenting an identical configuration to each side of the central plane of the element, whereby to present surfaces engageable with the keyways to prevent the key being pulled from a keyway other than longitudinally.

Preferably the key is made from a rigid material, more preferably from a metal or plastics material.

The invention will now be described further by way of example with reference to the accompanying drawings in which: Fig. 1 shows a cross-section on the line 1111 in Fig. 2.

Fig. 2 shows a front view of part of a plurality of concrete elements keyed together in accordance with the invention.

Fig. 3 shows a view, in the longitudinal direction of the keys and keyways, of a corner assembly for concrete members.

Fig. 4 shows a cross-section through a second arrangement for the key and keyways, at right angles to the longitudinal axis for the key, and, Fig. 5 shows a view similar to Fig. 4 of a third arrangement for a key and keyways.

In the arrangement illustrated in Figs. 1 and 2 two concrete members, generally indicated by reference numerals 11 and 12, present abutting surfaces 11 a, 1 2a respectively. The concrete member 11 comprises three concrete elements 13, 14 and 1 5 in stacked relationship and, in combination, presenting the surface 1 a and the concrete member 12 is defined by three concrete elements 16, 1 7 and 1 8 in stacked relationship and, in combination, presenting the surface 1 2a.

The elements 13,14,15,16,17 and 18 are of panel like construction with a configuration to one side of the central plane for each panel diametrically opposite to the configuration on the other side of the central plane of the element, and the central planes of all the elements 13, 14, 15, 16, 17 and 18 lie in a common plane, generally indicated by the plane XX in Fig. 1.

The element 13 has a keyway 1 3a in that surface forming part of surface 11 a, the mid-plane of the keyway 1 3a lies on the axis XX and said keyway 1 3a is open at both ends. The keyway 1 3a comprises, from the surface 11 a, a neck part 1 3b and an undercut part 1 3c, in the illustrated example presenting a part cylindrical surface based on an axis parallel to the surface 1 1a and lying on the axis XX.

The keyway 1 3a may be cut, as by grinding, in the element 13 but preferably the keyway 1 3a is formed whiist the element 13 is being cast.

The keyway 1 3a is lined with a keyway liner 19, of sheet metal, which may be inserted into the keyway 1 3a after the keyway 1 3a has been formed but preferably the keyway liner 19 is placed in the mould for the element 1 3 and the element 13 is cast around the keyway liner 19, so that the liner 1 9 forms the keyway 1 3a in element 13.

When the element 1 3 includes a metal reinforcement 20 the keyway liner 1 9 is preferably secured, as by welding, to the reinforcement 20, preferably prior to casting of element 13.

The elements 14 and 1 5 present keyways 1 4a and 15a respectively and the keyway liner 1 9 is located in each said keyway 1 4a and 15a. The keyways 1 4a and 15a, and their respective keyway liners 19, are identical in configuration and identically arranged as for the keyway 1 3a so that when the elements 13, 14 and 1 5 are assembled to define surface 11 a the keyways 13a, 14a and 15a, and the liners 1 9 therein, are in axial alignment.

The elements 1 6, 1 7 and 18 defining surface 1 2a have keyways 16a,17a, and 1 8a respectively, with liners 1 9 therein, identical with the keyways 13a, 14a and 1 5a and the keyway liners 1 9 therein, the keyways 16a, 17a and 1 8a and their respective keyways being diametrically opposite to the keyways 13a, 14a and 15a and their respective liners across the junction of the surfaces 11 a, 1 2a so that, when correctly assembled, the mid-planes of all the keyway liners 19 lie on the common plane XX and the keyway liners 1 9 define an opening extending from top to bottom (as viewed in Fig. 2) of the assembly 11,12.

The assembly 11, 12 is retained in fixed relationship by two keys 21 and 22 each of which comprises an elongate member of uniform crosssection, the cross-section of each of the keys 21 and 22 being substantially identical with the cross-section of the opening through the assembly 11, 12 defined by the aligned keyway liners 1 9.

The key 22 has a length equal to the vertical height of the element 1 5 or 1 8 plus half the vertical height of the element 14 or 1 7 (as viewed in Fig. 2) and the key 21 has a length equal to half the vertical height of the element 14 or element 17 plus the vertical height of the element 13 or 1 6 so that, when assembled in end-to-end relationship, the keys 21 and 22 present a length, equal to the vertical height of the assembly 11, 12 as viewed in Fig. 2.

When there is adequate access to both ends of the slot defined by the liners 19, as for example when the assembly 11 and 12 can be substantially horizontal, the keyway 22 is driven into the opening defined by the keyway liners from the free end of element 1 5 and 1 8 and the key 21 is driven into the opening defined by the liners 1 9 from the free end of the elements 1 3 and 1 6.

When there is not free access to both ends of the opening defined by the keyway liners 19, as for example when the assembly 11 and 1 2 is substantially vertical with the elements 1 5 and 1 8 resting on the ground, the key 22 may be driven vertically into the opening defined by the liners 1 9 with the elements 1 3 and 1 6 removed and, thereafter, with the elements 1 3 and 1 6 replaced, the key 21 can be driven into the upper part of the opening defined by liners 1 9.

It will be appreciated that with the above defined arrangement the keyways 21 and 22 engage with the keyways defined by the liners 1 9 on both sides of the junction of surfaces 11 a, 1 2a and, due to the "dumb-bell" shape of the keys 21 the elements 11 and 12 are locked together in fixed relationship. Further, as the keyway 22 extends through the elements 15 and 18 and partially through the elements 14 and 17, and as the key 21 extends through the elements 13 and 16 and partially through the elements 14 and 17 the elements 13, 14, 1 5, 1 6, 1 7 and 1 8 are locked together on the axis XX and the only way in which the assembly of elements 13, 14, 1 5, 1 6, 17 and 1 8 can be broken is by extraction of the keys 21 and 22 in the axial direction of said keys 21 and 22.

In the example illustrated in Figs. 1 and 2 the elements 13, 14, 15, 16, 17 and 18 are of identical height, as viewed in Fig. 2, but it will be appreciated that the elements may be of different vertical heights, to each side of the abutting surfaces 11 a, 1 2a, and, for example, member 11 may be a single element and the member 12 may comprise one or more elements in stacked relationship.

The arrangement illustrated in Fig. 3 shows an assembly comprising a corner post 31, a panel 32 secured to the post 31, and a panel 33 secured to the post 31 at right angles to the panel 32. The panel 32 is secured to the post 31 by a key 34 and the panel 33 is secured to the post 31 by a key 35.

The key 34 and 35 have an identical configuration to the keys 21 and 22 illustrated in the Fig. 1 and Fig. 2 embodiment, and said keys 34 and 35 act in identical manner to the keys 21 and 22 and, although not illustrated, the keys in post 31, panei 32, and panel 33 may include keyway liners, identical with the liners 1 9 in the Fig. 1 and Fig. 2 embodiment.

Fig. 4 shows an alternative cross-sectional configuration for a keyway, keyway liner, and key for securing together two elements 41 and 42 in abutting relationship and in this embodiment the keyways 41 a and 42a include a rectangular undercut, the liners 43 and 44 conform with the configuration of the keyways 41a and 42a respectively, and the key 45 is defined by an elongate member comprising a plate-like mid region 45a with enlarged side edge regions 45b and 45c of rectangular configuration.

In the arrangement illustrated in Fig. 5 for securing together two members 51 and 52 the keyways 51a and 52a are of dovetail configuration, the keyway liners 53 and 54 conform with the configurations of the keyways 53 and 54, and the key 55 comprises a plate-like mid-region 55a with enlarged side edge regions 55b and 55c, the overall cross-sectional configuration of the key 55 being substantially identical to, or closely similar to the opening defined by the liners 53, 54.

It will be appreciated that, by the method proposed by the present invention, two or more concrete members can be secured in fixed relationship, when a structure is being assembled from prefabricated units arranged in rows and in staggered relationship between adjacent rows, such as the relationship for brick or breeze block assembly, horizontally adjacent units can be secured together with a key, as defined by the present invention, vertically adjacent assemblies can be secured together by a keyway and key in accordance with the invention traversing horizontally across the abutting faces of adjacent layers, and, in another embodiment, adjacent members in one layer may be keyed to an adjacent layer by passing a key through the keyway formed by the two adjacent members in abutting relationship and further engaging the key in a recess, in the form of a keyway, in the element below or above the adjacent members.

In an alternative arrangement, to afford a convenient cavity wall construction, the inner and outer slabs defining the cavity walling may be accurately and securely locked together by a key, in accordance with the invention, extending across the cavity and engaging in keyways defined by the inner and outer blocks.

When the keys and keyways are to be used in external structures the keyway liners, and the keys, may be treated in accordance with conventional anti-corrosion processes or constructed of rigid materials resistant to corrosion, such as plastics material.

With the arrangements proposed thus far an assembly of concrete members, secured together by keys, can be broken down to its component elements, without damage, by simply extracting the keys longitudinally from the assembly but, for.

a more permanent construction, the keys and keyways may be grouted in or any cavities between the elements and the keyway liners, or the liners and the keys, may be charged with a mastics material and any spacing between the adjacent surfaces of the elements may be charged with a mastics material to further afford protection against corrosion and to render the assembly of a more permanent nature.

Whilst the present invention has been described by way of example with reference to specific embodiments the invention is not limited thereto and many modifications and variations within the scope of the appended claims will be apparent to persons skilled in the art.

Claims (20)

1. A method for securing together two concrete members in fixed relationship comprising the steps of forming a keyway in each member in such manner that the keyways in the two members register when said members are in desired relationship, and securing the members by slidably inserting a key into both keyways whereby the key bridges the junction of said members.

2. A method as claimed in claim 1 including the step of forming the keyway in each member whilst the member is being cast or moulded.

3. A method as claimed in claim 1 or 2 including the steps of forming a keyway liner of sheet material and inserting said keyway liner into a pre-formed recess in the respective concrete member.

4. A method as claimed in claim 1 or 2 including the steps of forming a keyway liner of sheet metal and casting the concrete member to include said liner.

5. A method as claimed in claim 4 including the steps of securing the keyway liner to a metal reinforcement for the concrete member and casting said member to include the liner and the reinforcement.

6. A method as claimed in any preceding claim comprising the steps of forming the keyway to have surfaces facing away from the direction of the second member and extending in the length direction of the keyway, and providing cooperating surfaces on the key, extending in the length direction of the key, to prevent the key from being pulled out of the keyway other than in the length direction of the key.

7. A method as claimed in any preceding claim including the step of sealing the key in said keyways to prevent erosion of the key.

8. A method as claimed in claim 7 including the steps of sealing the key in the keyways with a mastics material and forcing mastics material into the junction between the two members to protect that part of the key bridging said members.

9. A method as claimed in any preceding claim in which one of said concrete members comprises a plurality of concrete elements each of which is to be attached to the other member and comprising the steps of forming a keyway in each concrete element such that said element keyways are in axial alignment when the said concrete elements are in the desired relationship with the other member, and inserting the key, or keys in end to end relationship, into the keyways so that the, or each, key extends across the junction of at least two or more said elements.

1 0. in combination, two concrete members intended to be retained in fixed relationship by a key, each said member presenting a keyway open at that face of the member intended to be presented to the other member, and said keyways extending in parallel registered relationship to receive a key when said members are assembled in the desired relationship, and a key intended to be inserted longitudinally into said registered keyways.

11. A combination as claimed in claim 10 in which each keyway is defined by a metal liner embedded in a recess in its respective member.

12. A combination as claimed in claim 11 in which each concrete member includes a metal reinforcement and said metal liner is secured to said metal reinforcement.

13. A combination as claimed in claim 10, 11 or 12 in which the key, and each keyway, present co-operating abutment surfaces inclined to the general plane of the key and arranged to prevent displacement of the key from a keyway other than in the length direction of the key.

14. A combination as claimed in any preceding claim in which one of said concrete members comprises a plurality of concrete elements, each of which is intended to be retained in fixed relationship with the other member, and wherein each concrete element includes a keyway and the keyways of all said elements are axially aligned when said elements are in their desired position relative to said other member and whereby a common key has one side edge region inserted into the keyway in said other member and its other side edge inserted into all the aligned keyways in said elements.

1 5. A combination as claimed in any one of claims 10,11,12,13 or 14 in which the key comprises an elongate element of substantially uniform cross section.

16. A combination as claimed in any one of claims 10,11,12,13, l4orl5inwhichthekeyis made from a metal or rigid plastics material.

17. A method, as claimed in claim 1, and substantially as hereinbefore described.

1 8. An assembly of concrete members retained by the method set forth in claim 1.

1 9. A combination of concrete elements with a key as claimed in claim 10 and substantially as hereinbefore described.

20. An assembly of concrete members secured together in fixed relationship by a key or keys as claimed in claim 10 and substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.