CA1290956C

CA1290956C - Wall tie

Info

Publication number: CA1290956C
Application number: CA000549804A
Authority: CA
Inventors: Ernest B. Lapish
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-10-31
Filing date: 1987-10-21
Publication date: 1991-10-22
Also published as: NZ222216A; DE3736553A1; GB8724889D0; US5035099A; GB2196664A

Abstract

ABSTRACT

A wall tie connector for masonry-veneer, panels, or curtain-wall claddings, has a ductile attachment plate for attachment to a support frame or to the masonry, the panel, or the curtain wall, and has a pair of protruding apertured flanges in which a ductile bar with at least one keying portion is keyed into an aperture to prevent rotation about its longitudinal axis. A retaining tie member is slideably mounted on the bar, and is connectable to masonry veneer, a panel or a curtain wall, or to a support member. The ductile attachment plate may have secondary flanges orthogonal to the main apertured flanges, and so arranged as to penetrate an insulation layer or to key into a masonry wall.

Description

~, X~ 35 f;

FI~LD OF TH~ IMYENTION

This invention relates to a method and means for tying cladding ~uch as glass curtain wall~, or panels, or block or brick veneerg to an accompanying framework, and has partlcular appllcation for the accommodation of substantial in-plane movement of the framework structure vertically, horizontally, or pivotally with respect to the cladding, whilst at the ~ame time accommodating out-of-plane ~tresses arising from applied face loads.

The invention has particular, though not sole, application to a~eismic wall connections.

~RWND

The conætruction of brick or block buildings, and glass-walled buildings, is often performed with the use of a wooden, concrete or metal frame as the supporting mRmber, to which the outer wall, or "veneer~, of bricks or blocks or pansls or glass is linked by ties to prevent it from toppling outwards. It i~ well recognized by structural engineers experienced in the aseismic design of buildings that brittle non-structural elements such as masonry veneer~, precast panels or curtain wall constructions must be separated from the seismic resisting frame 80 as not to dify the seismic response of a building structure subjected to lateral loadR.

Substantial relative dynamic in-plane displacements of the veneer and the frame may occur under seismic attack during an earthquake, or under severe wind loadings, and can result in failure of currently known ties, resulting in severe damage to veneer walls and/or the support structure. Other strains apply in wooden-framed brick or block veneer buildings in the period after construction, when the wooden frame has a 90!~56 tendency to shrink and/or warp ~llghtly a~ lt lo~es molsture to the atmosphere, and the brick or block veneer expa~ds moisture from the at ffphere i8 ab80rbed.

P~IOR ~RT

Many different attempts have been made to provide veneer anchor6 to interconnect a veneer wall such a~ a ma30nry wall to a supporting frame work. These attempts have concentrated on the provision of a certain degree of adjustment between an anchor attached to a 6upport, and a wall tie which iB secured to the masonry wall, by embedding it into ths mortar layer between masonry unit~.

SCNWALB~R~ US Patent 4021990 Discloses a veneer anchor and dry wall construction system and method which utilise~ a wire U-shaped or V-shaped tie capable of moving vertically with respect to a channel formed in a anchor plate having a vertically projecting bar portion.

DAVIES US Patent 3213576 Discloses a fa tenlng mechanism for the marble front of a burial crypt. ~hi6 is concerned with a plate which is securely anchored to a concrete wall, the plate being slotted, so that it~ position can be adjusted vertically, prior to fixing, 80 that a marble facing can be supported on a ledge extending from the plate.

HUSL~R US Patent 3788021 Discloses an interconnection system for structural ele~ents.
It is concerned with the provision of an elastomer b~tween two channels, 80 that the two channels are resiliently connected together and also insulated one from the other.

HALA US Patent 4021989 Discloses a rotatably pivotal stons anchor and 3tone anchor construction system. This system allows for rotational adjustment of one end of the anchor from the other, allowing ~,~g()~56 one end to be fixed to a concrete wall, with the other having a button on the end th~rsof capable of fittlng lnto a reces~
ln an outer masonry plate.

LOPEZ US P~tent 4473984 Discloses a curtain-wall masonry-veneer anchor construction.
This utilises an eye bolt, connected to a V-shaped wire tie.

CHAMBERS US Patent 3715850 Discloses an adjustable mounting device. This u~es a circular plate having a plurality of apertures therein, enabling it to be positioned in any one of a number of positlons relative to a slotted plate.

HOHMANN US Patent 4598518 Discloses a pronged veneer anchor and dry wall conQtruction ~ystem. This utilises a U-shaped or V-shaped wlre tie almilar to that of Schwalberg described above.

ALLAN US Patent 4373314 Discloses a masonry veneer wall anchor. ~hi~ ~how~ an L-shaped metal bar having a series of slots in ths protruding vertlcal face thereof, each ~lot of which can recei~e a triangular wire tie, allowing the wire tie to be in~erted in the slot, for vertical adju~tment during placement of the tie on the relevant brick surface during construction of the masonry wall.

STORCH US Patent 3377764 Discloses anchoring means for masonry walls. This show~ a pair of perpendicular interconnected wire loops, each of which can be embedded in the mortar layer of separate masonry walls which are to be tied together.

~ARGTB EID~R West German Patent 2905238a Di~closes a "wnll facade substructuren. This has asymmetrically ~haped wall and facade profiles allowing for relative vert$cal di~placement by the provision of two .~

~ ~9(~356 channels, one of whlch has A s~rie~ of vertical ~lot~ thereln by whlch it may be att~chad to the other channel.

It will be noted that some of the~e connectors provide for vertical and to a leBser extent horizontal adjustment of the tle relative to an anchor plate during lnstallation. However these prior art connectors were not deslgnad to resist seismic attack or other dynamic movements. Some of them are sultable only for adju~tment during installation and are then locked fixedly in place. Thi~ may be suitable for masonry to ma~onry cavity connections but is not suitable for veneer wall constructions where significant relative displacements of a veneer wall and its support are possible.

For example, the Schwalberg tie consists of a vertical bar (26) which restrains a horizontal tie (56~. When the out of plana sei~mic load is applied to the tie at the mid-span of the bar, the bar can only bend outwards on each reversal of the cyclic loading, so that the vertical bar bends into the shape of a hoop. This bending in one direction only thu~
increases the slackness between the co~ponents, thereby radically altering the ~hape and ~ymmetry of tho hysteresis loop. When the Schwalberg horizontal tia is at the bottom, or top of the vertical bar, the shape of the hysteresis loop will be completely different when compared with the mid span position.

All the other cited ties of a similar configuration will have these types of irregular and unpredictable hysteresi~ cyclic performance loops.

s~ s~r OF nNVe~TIo~

It i~ an object of thi~ invention to provide an improved wall tie connector which allows for considerable in-plane movements of a veneer relative to its support fra~e, without compromising significantly the degree by which the veneer is supported by the frame.

1 X9()~35fi In one aspect, the lnventlon provides a wall ti~ conn~ctor for connecting a first wall structure to a second wall structure lncluding: a ductils attachment plate having means for attachment to a fir~t wall structure, said attachment plate having a palr of main flanges protruding from the plane of the attachment plate, each flange having an aperture thereln; a ductile elongate m~mber which can be ecured to said attachment plate by passing through aaid apertures ln said main flanges~ a retaining member having mean~ at or adjacent a first end thereof for attachment to a second wall structure, said retainlng member having an aperture at or sdjacent a second end thereof through which the ductile elongate msmber can pass to connect said retaining member to the attachment plate; wherein the ductile elongate member can be keyed to at least one of said apertures to prevent rotation of the elongate member about its longitudinal axi8t and wherein said retaining member aperture i8 only slightly larg~r than the width of the elongate member 80 that in use the retaining member is closely coupled to ~aid elongate member in ths axial direction of the retaining member and forms a sliding fit thereon 80 as to allow the retaining member to slide from side to side along the elongate member.

The width of the elongate member being meaæured in the direction of the major axis of the retaining member as this is the direction of push/pull forces exerted by face loads, e.g. as may be experienced in an earthquake.

The elongate member is in the form of a rod having at least one keying portion along its length ~called the ~keyed rod") 80 that it can be keyed into complementary shaped apertures in one or both of the flanges or the aperture in the retaining member ~or two or more of them) and 80 prevented from rotating about its longitudinal axis.

In its simplest form the elongate member may comprise a coach or carriage bolt which has a short neck length adjacent the ~ ~ ~O ~

head wlth a pair of flats which enables it to be keyed again~t rotatlon by fittlng closely lnto a corre~pondlng flat sided aperture ln one of the maln flanges.

More preferably the elongate rod has at least a pair of opposite flat longltudLnal faces along it~ length to key it to "vertical" ~ubstanti~lly rectangular slots within each of the main flanges and also to key Lt to a substantially rectangular aperture or substantially rectangular "vertical~
slot in the retaining me~ber. Other cross-sections can be uaed, e.g. the rod could hsve a polygonal cros~-sectlon with a multiplicity of "flats~ or, the rod could have a circular cross-section with a spline or an arcuate cut along its length to give a keying portion within the rod 80 that the rod is keyed to a complementary aperture ln at least the retaining member which in turn prevents the rod from rotating. Conveniently the rod has a square cross-section, and i8 formed with pre-bent ends, to prevent lateral displace~ent of the rod relative to the flange~.

Where the rod has pre-bent ends it will be generally convenient to provide key-hole type slot3 in the flanges, with the enlarged portion of the key-hole slots towards the top, 80 that the pre-bent square cro~s-section rod, wlth its associated retaining tie member can be in~erted through the larger upper end of the slots, and then rotated through 90 to lock it in place.

Where th~ wall ~tructure (e.g. a stud) is covered by insulation it i~ preferred that the attach~ent plate has additional central stiffening ~eans such as central orthogonal flange~ which can penetrate the insulation layer covering the ~upportlng framework, and keep main face of the attachment plate ~paced away from the insulation layer.

~ ~9o~s~i DRAWINGS

Th~e and other aspect~ of thi~ lnv~ntlon, whlch ~hould be considered in all its novel aspectY, will become apparent from the following description which is glven by way of example only, wlth reference to the accompanylng drawings, in whlch:

Flqure 1: illustrates a per~pectlve vlew of a first embodiment of the wall tie, connecting a masonry vene~r to an insulation covered metal stud.

Fiqure 2- illustrates a top plan view of the wall tle of figure 1, showing the possible ductile bendlng movement of the rod.

Fiqure 3:illustrates a top plan view of the wall tie of figure 1, showing the retaining member at the extreme end of the rod, and shows possible ductile bending vement of the cantilevered end of the attachment member.

Fiqure 4:illustrates a perspective Vi8W of a second embodiment, in which the attachment plat0 is connected to a load bearing bracket, which 18 in turn connected to the metal BtUd.

Fiqure 5: shows a third embodiment of the invention, in which the attachment plate is turned around and attached directly to a masonry veneer wall, whilst the retaining member is connected directly the supporting metal stud framework.

Fiqure 6:~hows a fourth embodiment of the invention, in which the attachment plate has the ductile rod fixed in place, and the retaining member ha~ a slot in one end.

Fiqur~ 7: shows a fifth embodiment of the invention, in which a simplified attach~ent plate i~ ~ecured to a timber ~tud.

~ x9o~

YI~ST ~O~IME~NT -- FIGURES 1 - 3 The wall tie of Figure 1 has three~ main components, an attachment plate 10, a keyed rod 11 and a retaining member 12.

The attachment plate 10 has a çlingle or a plurality of apertures 19 for the reception of fasteners 20, which are preferably self-tapplng screws, bolts or the lika for attachment to a stud 13, which i8 sho~n as a metal stud, covered by a layer of in~ulatlon 14.

The attachment plate 10 has a maln face 21 through which the fasteners can pass, a pair of protruding flanges 22, 23, and a pair of orthogonal flanges 25, capable of piercing the layer of insulation 14 and prassing against the end ~rall of the metal stud 13 ~o that the main face 21 stands proud of the layer of insulation ~as shown in figures 2 and 3).

It is preferred that the flange~ 25, stop short of the slotted flange~ 22, 23 80 that the central portion indicated by numeral 26 i9 supported by the flanges 25, but the outer edges of the main face 21 are unsupported in the regions marked 27 - 28. The importance of these unsupported regions 27, 28 will become apparent from an inspection of Figure 3.

The f langes 22, 23 are provided with substantially rectangular slots 30, 31 which are preferably in the form of "key-hole" type slot~, having an enlarged substantially circular upper portion 32, and a main portion 33 having straight sides. The main portion 33 is preferably only slightly wider than the width of the keyed rod 11. Indeed, the keyed rod 11 is preferably of rectangular, or more preferably squara crosf~-Yection, 80 that it can ~lide up and down the main portions 33 of the slots, but i8 prevented from rotating within the main portion of the ~lots. Nevertheless, the upper circular portions 32, are preferably sufiiciently large that the square cross-section rod 11 can be rotated in ~ X9(~9~;i6 g thi~ portion of the slots.

Prsferably the ~quare cross-ssctlon rod 11, is provlded wlth pre-bsnt ~nds 34, 35 whlch are bent at ~ub~tantlally rlght angles ~o the main axis of the rod, to restraln the ~nds of the rod from passing through the maln portion~ 33 of the slots, i.e. to prevent the rod from falllng out of the slot~
when in service.

The setaining member 12 has a substantlally vertical portion 40, ~nd a ~ubstantially horizontal portion 41, i.e. it has a twisted neck 42 jolning the two ends tog~ther 80 that one end can be slotted onto the rod, and the other end attach to a masonry veneer wall 43.

Preferably the end 40 has an aperture 43 therein which has a width 44 only sllghtly larger than the corresponding width of the rod 11 80 that the retaining member 12 forms a sliding fit on the rod 11, and can slide along the length of the rod.
By thls ~eans, the retainlng member 12 is closely coupled to the rod 11, in the axial direction of the retaining member 12, a~ will be explained below. As shown in figure 1, the aperture 43 i8 square to correspond to the cross-~ection of the rod 11, although this aperture could be of any other suitable Yhape, e.g. containing at least one flat 80 that it prevent~ the rod from rotating and i8 closely coupled to the square cross-section of the rod.

The horizontal portion 41 of the retaining member, preferably has recesses 46, 47 surrounded by fins 48, 49 to assist in keying the horizontal portion 41 into the mortar-masonry veneer wall and for the sngaging of vertical reinforcing bars located in the veneer.

It is particularly preferred that both the attachment plate 10, and the keyed rod 11, are formed of ductile materials.
It will be generally convenient to form them of ductile steel~, and by wPy of example, the following ~teela are ~ ~90956 -- ~o --suggested: structural mlld steal, which i~ pref~rably pl~ted, or one of th~ v~rietl~s of stalnleas ~teel. Other alloy~ ~ay be used, and lt wlll be apparent to those ~kllled in the art, that the ductile nature of these components can be cho~en as rsquired. It is preferred that lf the ductlle materlal i9 a metal which is subject to corroslon, that the mutal be coated with a compatibls anti-corro~ion layer, such as zinc, 8.g-, by hot-dip galvanizing after fabrication.

OP~RATION OF ~IRST XMBODIM~NT

In use, the wall tis can be reàdily assembled and in~talled by tradesmen. The retalnlng member 12 can be fed on to the keyed rod 11 (or supplied as a pre-assembled pair). The attachment plate 10 can be secured to a stud 13 by pu~hing the flanges 25 through the insulation layer 14 then using fastener~ such as ~crews or bolts, rivets, nails, etc.
passing through apertures 20, through the insulation layer 14, and into engagement with the stud 13. The fasteners can be used to pull the ends of the flangeA 25, tight agalnst the end wall of the stud, 80 that the central region 26 of the attachment plate is stiffened.

The retaining member 12 and rod 11, can now be attached to the attachment plate, as the retaining member is held with portion 41 in the vertLcal position, i.e. with the ends of the rod 11 facing upwardly, and one end passlng through the enlarged end 32 of the slots.

The other end of the rod 11, is then passed through the other slot, and the entire assembly pulled upwardly until the rod is positioned in the enlarged upper ends 32 of both slots.
At this point, the rod 11 can be rotated through 90, until the portion 41 of the retaining member 12 is in a substantially hori~ontal position, and then the rod and retaining ~ember can be slid down the slot~ until it reaches the position shown in figure 1. The retaining member 12 can then be bedded into the mortar of -the masonry veneer wall, 'i ~ X90956 "

and further maAonry element~, l.e., bricks or blocks can be bullt up o~ the wall in order to cover thq horLzont~l por ion 41. The wall will then be built up until another wall tle is required, and the process repeated.

Figures 2 and 3 show the dlsplacement of the ductlle members, i.e. the ductlle rod 11, and the ductile attachment plate 10, under severe face load.

If the retalning member 12 i~ positioned about the mid portion of rod 11, then face loads will cau~e the rod to flex back and forth in the bending manner ~hown in figure 2.
Extreme bending movement at the central portion of the rod 11 may also result in flexing of the ends of the flanges 22, 23.

If the retaining member 12 i8 at one or other end of the rod 11, then severe face loads will cause the appropriate flange, in this case flanqe 23 to flex back and forth about the unsupported portlon 28 of the main face 21 (which is ~ufficiently clear of the insulation layer to allow it to flex back and forth as shown in figure 3).

The retaining member 12 may be formed of any suitable material, e.g. metal or plastic. It need not be ductile, and in the case of a plastic retaining member 12, it wlll likely be of an elastic plastics material with a configuration such that portions 40 and 42 are strengthened to prevent deformation under axial horizontal loadings.

SBCOND EM~ODIM~N~ - FIGUR~ 4 In the second embodiment, the attachment plate 10 does not directly contact the stud 13, but instead contact~ a load bearing bracket 16, which in turn connects to the stud 13 by appropriate fasteners ~uch as screws 17 or the like. It will generally be convenient to provide additional apertures (not shown) in this bracket 16, 80 that the screws or other asteners pas~ing through the attachment plate 10, secure it ~ ~30~35~

to the load retalnlng bracket 16, and al~o to the stud 13.
Depending upon the ~chickn~s of thls lnsulatlon layer 14, the attachment plate 10 may be connected only to load bearing bracket 16.

In this case the keyed rod is a coach bolt 111 having a circular cross-section shank for most of lts length, a ~hort threaded portion 112 at one end, and a short keying portion 113 at the other end adjacent a head 114. The keylng portlon i~ provlded by a pair of opposite flat faces 115 ~which are oriented vertically 80 as to fit snugly within the slot 117 and prevent rotation of the bolt ~bout its longitudlnal axis). Conveniently the flats 115 are of such a size that the bolt can only be inserted in slot 17 in the orlentation shown in figure 4.

The retaining member 12 has a circular aperture 120 in end 40, ~o that it i~ closely coupled to the bolt in its axial direction, but can sllde from side to side of the bolt.

In use, the free end 112 of the bolt 111 is paqsed through slot 117, aperture 120 of the retaining member, then slot 118 as shown. A nut 121 or other securlng mean~ 18 used to hold the bolt in place and prevent the keying portion 115 from escaping from the slot 117. The nut may be secured by appropr~ ate locking means such as an anaerobic adhesive, locknut, spllt pin, or the like.

T~IRD E:NBODIME~T - FIGURIS 5 This shows the use of an attachment plate 10 of the same style as that shown in figure 4 ~i.e. with the shorter orthogonal flanges 25, shown in Figure 1), but in thl~ case with the attachment plate 10 secured to a masonry veneer wall rather than to a stud. The attachment to the masonry veneer, can be by way of a threaded brick tie 50 embedded in a mortar layer 51 between bricks 52, 53.

1 2~0956 A retalnlng member 60 19 connected to a ~tud 13, by meam~ of screws or the like, passlng through the oaln wall 62 of tho stud. An ln~ulatlon layer 63 18 conveniently connecte~l to the end wall of the stud by appropriate fastenera 64. Note that the retaining msraber whlch 18 poElitioned vestically, wlll cut through a portion oi the insulation.

It 18 pre~erred that the retalning me~ber ha~ an elongated slot 65 of ~ubstantially rectangular cross-section, which i8 agaln closely coupled to the rod 11, in the axial diractlsn of the retalning member, but allows the retainlng m~Dber to move up or down with respect to the rod.

It is preferred that the retaining member also has a drip lug 66 positioned below the slot.

Assembly and operation of the third embodiment is similar to that o the first embodiment, except that the attachment plate 10 is sscured to the masonry veneer wall, with its flanges 25, acting to space the main face 21 away from the face o the masonry veneer, to enable the ends 27, 28 to flex in the manner shown in figure 3. In use the rod 11 can also f lex in the manner shown in figure 2.

FOURTH ~MBODIM~NT -- FIGURE 6 This shows an embodiment similar to Figure 1, but with the keyed connector rod 11, fixed in place within two apertures 71, 72, and the retaining member 70 having a vertical slot 73 which allows the up and down movement of the retaining men~er 70 relative to the attachment plate 10.

Prsferably one end 75 of the rod 11 is bent over, whilst the other end 76 iR straight 80 that the rod can be inserted from either snd, but inserted from the left in the example shown i.e. through the complementary ~square) aperture 71, through slot 73, then through aperture 72, and held in place by ~uitable fastening means e.g. a pin 78 which may be secured 9~

ln place. Many other fastenlng me~ns may be used.

FIrr8 ~soDIM~T -- Flguro 7 This shows a simpllfied attachmsnt plats 80 nailsd flush agalnst the faas of a timber stud 81 80 that the flangad ends 83, 84 of the plate overhand the sideb of the stud. A
square-section rod 85 is keyed into the lower portion of ~lota 86, B7 in the flanges and to a sguare hole 88 in the snd of a retaining member 90. The rod may have pre-bsnt ends 91 as shown.

Screws 93 can be used to tlghtly hold the centr~ of th~ plate 80 agalnst the stud, with nalls in apertures 94 near the edges of th¢ stud to provide additional stiffening ~eans.
Different nailing patterns can be used depending upon the extent of stiffening required and the nails could also replace the screws 93. Alternatively, pre-formed nail-plats fixings may be punched in the attachment plate and used to secure the attachment plate to the stud.

Th8 slots 86, 87 can have key-hole ends 95 to facilitate sntry of the rod 85 (as previously described).

The reta~ning member 90 can have tabs 92 to as~lst in keying it into the mortar of a masonry veneer wall.

Such a configuration can be used with studs of wood, metal, or any other material which are not covered by a layer of insulation.

aDVANTAG~S

In the foregoing embodiments, horlzontal movement is made possible b5~ the retaining member sliding along the rod, vertical moven!ent is possible with the rod sliding in the slot~ in the attachment plate 4 (embodiments 1 - 3 or 5), or ths slot in the retalning member ~embodiment 4), and 5~

rotatlonal ~oYement 1~ made posslble about the ma~or axl~ of the tle by the combin~d left or rlght hand plvotal actlons of the ~lldlng vertlcal and horlzontal cGmponent~. Additlanally, out-of-pla~o face load~ can be accommodated by:

(a) the rod as shown ln flgure 2 flexlng back and forth in the manner of a ductile simply ~upported beam ~as it i~ prevented from rotating about its axis and thus prevented from fllpplng over)l and (b) by cantllever flexing of the ductile attachment plate when out-of-plane face loads are applled to elth~r end of the ductile rod as shown in figure 3.

The wall tie connector of this invention is 80 structured that the flexural components, together with their closely coupled ~echanism provides a controlled symmetrical cyclic hysteresi~ load deflection loop, having a constant pinch of the loop due to the sliding fit and slackness between the component part~, but able to resist out-of-plane loads irrespective of the location of the retaining ~ember along the elongate member, or of its vertical positioning in the slotted flanges of the attachmunt plate or in the slot contained in the retaining member.

VARIATIONS

The stiffening means may take the form of an additional central rectangular plate or washer in front or behind the main face of the attachment plate. Or it may take the form of orthogonal flanges faclng away from the stud (i.e. towards the retaining member), or the plate main face 21 may be swaged, or in the case of direct contact with the stud (as in figure 7) the centre of the attachment plate may simply be tlghtly held again~t this face of the stud.

Many different types of attachment means may be used to attach the attachment plate to a fir~t wall structure such as a stud. In additlon to the bolts, screws, nall~ or nalllng-plates mentloned above, appropriate adh~slves may be used, or thu stud ~ay be provlded w1th a channel or reces~ into which a part of the sttachment plate may be fltted.

The rod 1~ prevented from rotatlng about it~ longltudinal axis by the interactlon of at lea~t part of the length of ths rod and one or more of the apertures in whlch the rod i~
positioned. ~hus the rod may be a coach bolt, or a square sectlon or polygonal ~ection bar or have a po~ltive or negative arcuate profile to make wlth a negative or positive arcuate profile in the ductile elongate member.

Finally, it will be appreciated that various alterations or modifications can be made to the foregoing without departing from the spirit or scope of this invention.

Claims

1. A wall tie connector for connecting A first wall structure to a second wall structure including:

a ductile attachment plate having means for attachment to a first wall structure, said attachment plate having a pair of main flanges protruding from the plane of the attachment plate, each flange having an aperture therein;

a ductile elongate member which can be secured to said attachment plate by passing through said apertures in said main flanges;

a retaining member having means at or adjacent a first end thereof for attachment to a second wall structure, said retaining member having an aperture at or adjacent a second end thereof through which the ductile elongate member can pass to connect said retaining member to the attachment plate;

wherein the ductile elongate member can be keyed to at least one of said apertures to prevent rotation of the elongate member about its longitudinal axis;

and wherein said retaining member aperture is only slightly larger than the width of the elongate member so that in use the retaining member is closely coupled to said elongate member in the axial direction of the retaining member and forms a sliding fit thereon so as to allow the retaining member to slide from side to side along the elongate member.

2. A wall tie as claimed in claim 1 wherein the ductile elongate member has a keying portion along at lease a major portion of its length to key it to the aperture in the retaining member.

3. A wall tie as claimed in claim 1 wherein the ductile elongate member has a keying portion at at least one end thereof to key it to at least one of the apertured in the said pair of flanges.

4. A wall tie as claimed in claim 1, wherein the ductile elongate member is a coach bolt.

5. A wall tie as claimed in claim 1, wherein the ductile elongate member is a rod having a substantially square cross-section.

6. A wall tie as claimed in claim 1, wherein the attachment plate has additional central stiffening means.

7. A wall tie as claimed in claim 6, wherein the stiffening means comprises a pair of orthogonal rearwardly extending flanges which are positioned substantially central of the attachment plate so that the attachment plate has a pair of unstiffened zones one on either side of the central stiffening means to allow ductile movement of the main flanges.