Patent Description:
An expansion joint is a physical break or gap in the continuity of construction of a building, bridge and other such structures where movement arising from the drying shrinkage of components laid when wet, the expansion and contraction caused by thermal gain and loss, the impact of wind loading and particularly earthquakes affecting structures built in seismic zones can be accommodated.

These expansion gaps extend through floors, internal and external walls as well as ceilings and roofs effectively dividing a structure into sub-sections which can largely move independently of each other; the aim being to break the aggregate effect of the above movements into smaller more manageable deflections and thereby limit the impact of movement upon a structure.

These expansion gaps require expansion joint covers which are used not only to accommodate the movement but for instance in the case of expansion gaps in floors to allow these floors to be trafficable. Similarly, in external walls and roofs they are used to accommodate movement and to seal the building against the ingress of wind, water and other contaminants.

Due to the growth in world population and the increasing numbers of people living in cities the size of buildings is increasing and the methods of construction changing. The impact of this has been to increase the width of expansion gaps. Similarly, as many larger structures are being built in seismic zones this has had a dramatic impact on expansion gap widths in these areas. This has presented problems in the supply of effective expansion gap covers which can span these wider gaps and accommodate the increased movement. Existing expansion joint cover design as reflected in prior art collectively does not adequately address the problems of expansion joint covers designed for increasingly wide expansion gaps with similarly increases in anticipated movement.

Currently two types of expansion joint cover are used to serve all or part of these markets. The first of these is described in <CIT> wherein an expansion joint cover comprising two sloping edge members fixed either side of the expansion gap. These edge members are linked by centring bars which are further attached to a central pan by use of spring-loaded bolts. The central pan has sloping side members the angles of which correspond to the angles of their adjacent side members. Opening and closing of the expansion gap causes the centring bars to rotate thereby causing the central pan to remain in a mid-position. Small gaps are left between the central pan and the two opposing sloping edge members and these gaps accommodate the impact of small deflections upon the structure. Under earthquake conditions the expansion gap can close more than the small gaps can accommodate and in such an event the sloping side angles of the central pan meet the sloping faces of the fixed edge members. In this event the central pan is forced upwards and the springs compressed until point where the pan has been ejected from the gap and the expansion gap can close more fully.

The fundamental problem with the central pan and centring bar system is that it relies solely on centring bars and the attendant bolts and springs to effect movement and displacement of the central pan. As expansion gaps become larger the central pan becomes correspondingly wider. In most instances the central pan incorporates an infill material such as paving or cladding elements and the mass of central pans increases significantly and therefore this load places greater strain upon centring bars, bolts and springs. In addition, centring bars must become much longer to be able to span the wider expansion gaps and the greater movement that these expansion gaps are designed to accommodate. The potential for failure increases with load, the magnitude of displacement and the length of the centring bars particularly during a seismic event where enormous forces are applied over very short timeframes.

Centring bars also extend into the expansion gap and thereby can either inhibit the closing of said gap in response to structural deflection or when the expansion gap closes the centring bars can be damaged and the expansion joint cover system compromised as part of this failure.

A second type of expansion joint cover comprises a central pan or plate system which is affixed by a hinge mechanism to one side member on one side of the expansion gap and the other side is free to move. A small gap is left between the central pan or plate and the opposing side member and this gap accommodates the impact of small deflections upon the structure. Under earthquake conditions the expansion gap can close more than the small gap can accommodate and in such an event the central pan or plate pivots from the fixed, hinged end rotating to allow the expansion gap to close and open. Patent references <CIT> and <CIT> exemplify this type of system where a hinge mechanism is created at one side of the expansion gap and the central pan or plate pivots around this hinge akin to the operation of a door. Various mechanisms are used to return the central plate or pan to its original position including elasticated cords, inertial reels, magnetic contacts and gravity.

The weaknesses in this design are numerous in that the system should not be used in floors where the once the central pan or plate pivots under movement it acts as a trip hazard to pedestrians and will not meet the requirements of current disability legislation. This problem also impedes wheeled vehicles and other traffic. When used in external walls the underlying expansion gap can be left exposed to the elements and the hinged plate subjected to wind loading. In these types of system, the mechanisms used to return the central pan or plate to its original position following a seismic event are complex and cumbersome.

In some instances, services, acoustic suppression materials, fire barriers, waterproofing membranes and other devices may be incorporated within an expansion gap provided the gap is wide enough to accommodate anticipated deflection and not impact the items installed within said expansion gap. As a result, it becomes desirable to be able to inspect these items particularly after a seismic event to determine whether they have remained unaffected or need to be replaced. The normal method of achieving this is to remove the entire expansion joint cover and in doing so abutting finishes are often compromised and must be replaced. Ideally only the central plate or pan would be removed, inspection and where required repairs or replacement of affected parts undertaken, and the central pan or plate replaced afterwards. No such system currently exists.

<CIT> relates to a gap closing device for an adjacent structure which aims for free connection of the floor, side wall, ceiling and roof of an adjoining building individually constructed.

<CIT> relates to a type of highway-bridge expansion joint structure.

<CIT> relates to a seismic joint, for covering a gap defined between a first and a second structural element, comprises: a first anchoring portion to be steadily associated with the first structural element; a first interconnecting portion rotatably connected to the first anchoring portion; a covering element having a first end rotatably in engagement with the interconnecting element and a second end able to be engaged in a slidably supported relationship on the second structural element.

<CIT> relates to a type of modulus formula bridge extension joint.

Accordingly, there is a need to address the above outlined deficiencies of the prior art.

The present teachings relate to an expansion joint cover for insertion in an expansion gap comprising a first frame section for attachment to a substrate at one side of the expansion gap, the first frame section having a flat surface; a second frame section for attachment to a substrate at an opposite side of the expansion gap, the second frame section having a first connector; a centre section configured to span the expansion gap and slide on the flat surface of the first frame section, the centre section having a second connector; and a linkage section configured to engage with the first and second connectors to connect the centre section to the second frame section, wherein the linkage section can pivot within the first and second connectors to allow movement of the centre section with respect to the second frame section.

The expansion joint cover in accordance with the present teachings may be further configured such that during movement horizontal to the plane of the substrate, at least a portion of the flat surface of the first frame section can slide under at least a portion of the centre section and at least a portion of the centre section can slide on at least a portion of the flat surface.

The expansion joint cover in accordance with the present teachings may be further configured such that when movement horizontal to the plane of the substrate causes the expansion gap to close to a predetermined point, the centre section engages with a portion of the first frame section causing the centre section to move vertically with respect the plane of the substrate.

The expansion joint cover in accordance with the present teachings may be further configured so that when the centre section moves vertically, the linkage sections pivot within the first and second connectors to maintain the centre section parallel with the flat surface of the first frame section. The linkage may be one of (i) a torsion spring, which applies force resisting vertical movement of centre section with respect to the plane of the substrate and (ii) a solid linkage.

The expansion joint cover in accordance with the present invention comprises two linkage sections configured to connect the centre section to the second frame section.

Optionally, at least one of the linkage sections is a torsion spring, which applies force resisting vertical movement of centre section with respect to the plane of the substrate and at least one of the linkage sections is a solid linkage.

Optionally, the connectors are C-shaped retainers and the linkage sections are barbell shaped.

The expansion joint cover in accordance with the present teachings may further comprise a first wing section attached to a first side of the central section and extending to the first frame portion. The expansion joint cover in accordance with the present teachings may further comprise a second wing section attached to a second side of the central section and extending to the second frame portion.

Optionally, the wing section is configured to pivot with respect to the central section.

Optionally, the centre section is a flat plate.

Optionally, the centre section is a pan with central recessed portion.

Optionally, the pan comprises an arm with a roller mechanism configured to slide on the flat surface of the first frame section.

Optionally, the first frame section further comprises an inclined portion extending from the flat surface configured for engaging with the pan.

The expansion joint cover in accordance with the present teachings may further comprise a backer rod topped by a sealant between the pan and at least one of the first frame section and second frame section.

The sealant may be configured to stretch during movement horizontal to the plane of the substrate.

Optionally, the first frame section comprises a first recessed portion, the pan comprises a second recessed portion and a pre-extruded seal connects the first frame section and the pan via the first and second recessed portions.

Optionally, the second frame section comprises a third recessed portion, the pan comprises a fourth recessed portion and a seal connects the second frame section and the pan via the third and fourth recessed portions.

The pan may comprise at least one of a first side inclining towards the first frame portion and a second side inclining towards the second frame portion.

The expansion joint cover may further comprise a first protrusion which extends from the flat surface of the first frame section and is configured such that the centre section can slide on the first protrusion.

The expansion joint cover may also comprise a second protrusion which extends from the centre section and is configured to engage with the first protrusion.

The present teachings also relate to an expansion joint cover for insertion in an expansion gap comprising a first frame section for attachment to a substrate at one side of the expansion gap, the first frame section having a flat surface; a second frame section for attachment to a substrate at an opposite side of the expansion gap, the second frame section having an upper section with a first connector and a lower section with a second connector; a centre section configured to span the expansion gap and slide on the flat surface of the first frame section, the centre section detachably connected to the upper section of the second frame portion; and a linkage section configured to engage with the first and second connectors to connect the upper section of the second frame section with the lower section of the second frame section; wherein the linkage section can pivot within the first and second connectors to allow movement of the upper section with respect to the lower section and the centre section is removable from the expansion joint cover by detaching it from the upper section of the second frame section.

Optionally, the centre section is a pan configured for attachment to the upper frame section using a countersink screw that extends through a portion of the pan into the upper frame section.

Optionally, the centre section is a pan configured for attachment to the upper frame section using a bolt that extends through a portion of the pan and through a portion into the upper frame section.

The bolt may extend through an upstanding wall of the pan and through an upstanding portion of the upper frame section.

Optionally, the centre section is a flat plate configured for attachment to the upper frame section using a countersink screw that extends through the plate into the upper frame section.

The present teachings provide an expansion joint cover designed to span an expansion gap in a structure wherein the expansion gap cover moves in response to movements in the underlying structure. The joint cover has been designed to accommodate two types of movement namely cyclical and non-cyclical movement of the structure in response to drying shrinkage, thermal gain and loss and wind loading which is often termed 'normal deflection' and is generally significantly less than the movements experienced during a seismic event where movements are termed 'seismic deflection'.

Structures exhibit two differing movement types (normal and seismic), which may be subdivided into non-cyclical and cyclical movements:.

The joint cover in accordance with the present teachings has been designed to accommodate these differing movement types in two different ways and to allow the cover to be tailored to meet these deflections individually.

In a first embodiment of the present teachings herein described as Type <NUM> the device is shown in <FIG>, <FIG>, <FIG>, <FIG>.

<FIG> shows a sectional view of the Type <NUM> version of a device designed to span expansion gaps in structures said device designed to open and close in response to movements in the structure whilst completely covering the underlying expansion gap. This figure shows a device comprising a frame <NUM> designed to be affixed by bolts <NUM> (or any suitable fixing means) to the substrate <NUM> on one side of the expansion gap <NUM> wherein the frame <NUM> has a substantially flat surface <NUM> with a sloping upstand <NUM> at the end of frame <NUM> said upstand <NUM> being designed to exert force on the end of the centre plate <NUM> of a second composite frame causing this centre plate <NUM> to lift under this pressure. <FIG> also shows an assembly designed to be affixed to the opposing side of the expansion gap <NUM> wherein this assembly comprises a lower frame <NUM> which is connected to the substrate <NUM> by bolts <NUM> (or any suitable fixing means). The lower frame <NUM> has multiple C-shaped retainers <NUM> and <NUM> into which barbell shaped sections <NUM> and <NUM> are inserted said barbell-shaped sections <NUM> and <NUM> being further attached by C-shaped retainers <NUM> and <NUM> to centre plate <NUM> which forms the upper part of this assembly.

<FIG> shows C-shaped retainers <NUM>, <NUM>, <NUM> and <NUM> or which have been designed to entrap the ends of the barbell shaped sections <NUM> whilst at the same time allowing them to rotate in response to pressure on the centre plate <NUM> from the opposite frame <NUM>. Depending upon the design requirements, anticipated movement and expected load capacity requirements of a structure any number of C-shaped retainers may be formed in the underside of the centre plate <NUM> and the upper side of the lower frame <NUM> rather that the four C-shaped retainers shown.

In <FIG> the centre plate <NUM> spans the expansion gap <NUM> and extends part way across the flat surface <NUM> of frame <NUM> such that there is a space <NUM> between the leading edge <NUM> of the centre plate <NUM> and the sloping upstand <NUM> of the opposing frame <NUM>. In this form when used in a floor location preferentially the ends of the centre plate <NUM> are chamfered or sloped <NUM> and <NUM> to assist in smooth transit across the expansion joint cover by wheeled vehicles and to meet the requirements of current disability legislation. The ends of centre plate <NUM> may incorporate seals in the underside said seals being used to prevent the ingress of water and other contaminants.

This configuration allows a given magnitude of movement whereby the centre plate <NUM> is in contact with the flat surface <NUM> of the frame <NUM> and accommodates opening and closing movement of the expansion gap <NUM> whilst providing a substantially flat surface which permits pedestrians and traffic to cross the expansion joint cover. Normally this level of movement is tailored to accommodate both cyclical and non-cyclical movement of the structure in response to drying shrinkage, thermal gain and loss and wind loading. This movement is often described as 'normal deflection'.

<FIG> shows a sectional detail of the Type <NUM> invention when the expansion gap <NUM> has closed in response to 'normal movement' wherein the centre plate moves in response and the leading edge <NUM> of this centre plate <NUM> slides across the surface <NUM> of the opposite frame <NUM> until it reaches the sloping upstand <NUM>.

As shown in <FIG> the flat surface <NUM> of frame <NUM> allows the expansion gap <NUM> to close until the leading edge of the centre plate <NUM> touches the sloping upstand <NUM>. This closing movement serves to accommodate deflections arising from 'normal deflection' forces. The centre plate <NUM> remains in contact with the flat surface <NUM> of the frame <NUM> and accommodates opening and closing movement of the expansion gap <NUM> whilst providing a substantially flat surface which permits pedestrians and traffic to cross the expansion joint cover.

<FIG> shows a sectional detail of the Type <NUM> invention when the expansion gap <NUM> has closed in response to structural deflections greater than 'normal movement' such as seismic movement wherein the leading edge <NUM> of the centre plate <NUM> meets the sloping upstand <NUM> of the opposite frame <NUM> this centre plate <NUM> is forced upwards causing the barbell shaped sections <NUM> and <NUM> to rotate as shown in <FIG> thereby lifting the centre plate <NUM> whilst ensuring that it remains parallel with the plane of both the lower frame <NUM> and the opposite frame <NUM>. Further closure of the expansion gap causes the upper plate <NUM> to extend beyond the end of the opposite plate <NUM> and across the surface of the substrate <NUM>.

<FIG> shows a sectional detail of the Type <NUM> invention when the expansion gap <NUM> has opened in response to 'normal deflection' wherein the substrate <NUM> and/or <NUM> withdraws and either frame <NUM> or the centre plate <NUM> and lower frame <NUM> withdraw being connected to each other through the barbell shaped sections <NUM> and <NUM> and to the substrate <NUM> thereby extending to span the increased width of the expansion gap <NUM>. Frame <NUM> has an extended tongue <NUM> which supports the end of the centre plate <NUM> as it spans the expansion gap <NUM>. In this form when used in a floor location preferentially the ends of the centre plate <NUM> are chamfered or sloped <NUM> and <NUM> to assist in smooth transit across the expansion joint cover by wheeled vehicles and to meet the requirements of current disability legislation. The centre plate <NUM> may incorporate seals in the underside said seals being used to prevent the ingress of water and other contaminants.

As shown in <FIG> when the expansion gap <NUM> opens in response to 'normal deflection' the substrate <NUM> and/or <NUM> withdraws and either frame <NUM> or the centre plate <NUM> and lower frame <NUM> withdraw being connected to each other through the barbell shaped sections <NUM> and <NUM> and to the substrate <NUM> thereby extending to span the increased width of the expansion gap <NUM>. Frame <NUM> has an extended tongue <NUM> which supports the end of the centre plate <NUM> as it spans the expansion gap <NUM>. The length of the tongue and the cantilevered portion of the centre plate <NUM> are generally tailored to accommodate the maximum expected opening movement of the expansion gap <NUM> whether such movement arises from 'normal deflection' or 'seismic deflection.

<FIG> shows a sectional detail of the Type <NUM> invention when the expansion gap <NUM> has opened in response to 'seismic deflection' greater than the 'normal deflection' shown in <FIG>. In this instance the substrate <NUM> and/or <NUM> withdraws and either frame <NUM> or the centre plate <NUM> and lower frame <NUM> withdraw being connected to each other through the barbell shaped sections <NUM> and <NUM> and to the substrate <NUM> thereby extending to span the increased width of the expansion gap <NUM>. The centre plate <NUM> has withdrawn further than shown in <FIG> whilst still being supported by the extended tongue <NUM> and the device continues to span across and cover the expansion gap <NUM>.

<FIG>, <FIG>, <FIG>, <FIG> also serve to indicate that the movement capacity of the device can be adjusted to meet the movement requirements of a structure by varying the width of the centre plate <NUM>, the length of the flat surface <NUM> of frame <NUM> and the width of the tongue <NUM> extending from frame <NUM>. This is a substantial improvement over the design of other expansion joint systems in that an expansion joint cover can now be readily configured to match the projected deflections of the structure. Similarly, the thickness of these elements can be varied to support anticipated loadings upon the device whilst in service.

Proposed components and assembly details for the device are shown in <FIG> wherein these components can comprise shaped torsion springs <NUM> interspersed between barbell-shaped sections <NUM> and/or <NUM>. Said torsion springs <NUM> being incorporated to force the centre plate <NUM> or pan-shaped section back to its original position following a movement cycle wherein the centre plate <NUM> has been displaced as shown in <FIG> and then returned to the positions shown in <FIG>, <FIG> or another position wherein the centre plate <NUM> returns to rest on the flat surface <NUM> of the opposing frame <NUM>.

In alternative designs the device can incorporate hydraulic mechanisms as alternatives to torsion springs <NUM> said hydraulic mechanisms designed to force the centre plate <NUM> or pan-shaped section back to its original position following a movement cycle wherein the centre plate <NUM> section has been displaced as shown in <FIG> and then returned to the positions shown in <FIG>, <FIG> or another position wherein the centre plate <NUM> returns to rest on the flat surface <NUM> of the opposing frame <NUM>.

<FIG> shows one possible configuration of a barbell-shaped section <NUM> which is used to link the centre plate <NUM> to the lower frame <NUM>. The rounded ends of this component fit into and are entrapped by C-shaped sections in centre plate <NUM> and the lower frame <NUM>.

<FIG> shows one possible configuration of a torsion spring <NUM> said torsion spring being interspersed between barbell-shaped sections <NUM> by being similarly entrapped by the C-shaped retainers <NUM>, <NUM>, <NUM> and <NUM>. The purpose to these torsion springs is to return the centre plate <NUM> back to its original position following a movement cycle wherein the centre plate <NUM> has been displaced as shown in <FIG>.

<FIG> shows a drawing of one possible configuration of a suitable torsion spring <NUM> which is stressed in bending being rotated in angular deflection and offering resistance to externally applied torque whereby the coil diameter is reduced, and the body length increases as they are deflected. In this instance the device comprises two torque coils <NUM> and <NUM> and a further coil <NUM>. These coils are slightly less than the inner diameter of the C-shaped retainers <NUM>, <NUM>, <NUM> and <NUM> formed respectively in the underside of the centre plate and lower frame. The coil <NUM> does not act under torque but simply serves to locate the spring within the C-shaped retainers. <FIG> also shows the ends <NUM> and <NUM> of the torsion springs which serve to both locate the spring over the upstands formed by the C-shaped retainers and provide resistance to spring rotation. These arms <NUM> and <NUM> also contribute to the lengthening of the spring sections under torque.

<FIG> shows the action of the torsion spring <NUM> described in <FIG> where the arms of the torsion spring <NUM> are held and loop over an upstand <NUM> on the lower frame. The torsion spring coil <NUM> is then rotated through externally applied torque in an angular deflection <NUM> moving the coil <NUM> from position A to position B. When the externally applied torque is removed the torsion coil <NUM> rotates back <NUM> to its original position wherein the coil <NUM> moves from position B to position A.

<FIG> shows an assembly of barbell shaped section <NUM> and torsion spring <NUM>. That is, this is one possible configuration for inserting barbell shaped sections <NUM> and torsion spring <NUM> within the C-shaped retainers or connectors. The person skilled the art will appreciate that any combination of barbell shaped sections <NUM> and torsion springs <NUM> can be chosen.

<FIG> shows a combination of barbell-shaped sections <NUM> and torsion springs <NUM> being installed in the C-shaped retainers <NUM> and <NUM>. Optionally C-shaped retainers may contain only barbell-shaped sections <NUM> or torsion springs <NUM>. Similarly, varying combinations of barbell-shaped sections <NUM> and torsion springs <NUM> may be installed in C-shaped retainers <NUM> and <NUM>.

<FIG> shows a continuous barbell-shaped section <NUM> and torsion being installed in the C-shaped retainers <NUM> and <NUM>. In other iterations varying combinations of barbell-shaped sections <NUM> and torsion springs <NUM> may be installed in C-shaped retainers <NUM> and <NUM>.

<FIG> shows a plan view of a series of differing configurations of barbell-shaped sections <NUM> and torsion springs <NUM>. The ratio of torsion springs <NUM> to barbell-shaped sections <NUM> along the length of a specified expansion joint cover assembly will determine the magnitude of torque required to force the centre plate (shown as <NUM> in <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and <FIG>) upwards. The greater the number of torsion springs the greater the force required to rotate the barbell-shaped sections <NUM> and <NUM>.

This is an important aspect of the present teachings as it permits the device to be readily tailored to application. As noted earlier and shown in <FIG> when an expansion gap closes beyond its 'normal deflection' limit the leading edge <NUM> of the centre plate <NUM> meets the sloping upstand <NUM> of the opposite frame <NUM> and this centre plate <NUM> is forced upwards causing the barbell shaped sections <NUM> and <NUM> to rotate as shown in <FIG> thereby lifting the centre plate <NUM> whilst ensuring that it remains parallel with the plane of both the lower frame <NUM> and the opposite frame <NUM>. Further closure of the expansion gap causes the upper plate <NUM> to extend beyond the end of the opposite plate <NUM> and across the surface of the finishes <NUM>. When and if this movement is reversed the centre plate <NUM> should return to its original position. Otherwise it will create a trip hazard is installed in floors as well as allowing penetration of water and other contaminants if used in floors, walls and roofs.

When an expansion joint cover is installed in a floor, 'seismic movement' having initially caused the centre plate <NUM> to lift followed by the expansion gap <NUM> opening thereby potentially allowing the centre plate <NUM> to return to its original position the force of gravity may aid closure of the centre plate <NUM>. Hence fewer torsion springs may be required to return the centre plate <NUM> to former position in expansion joint covers installed in floors when compared to joints installed in vertical and ceiling applications.

External expansion joint covers in walls and on roofs may be subjected to substantial wind loading and cannot rely upon the assistance of gravity to close the centre plate <NUM> to its original position. In this instance a larger number of torsion springs may be required than in the equivalent floor expansion joint cover.

Expansion joint covers affixed to cover expansion joints in ceilings cannot rely upon the assistance of gravity to close the centre plate <NUM> to its original position. In this instance a larger number of torsion springs may be required than in the equivalent floor expansion joint cover.

Hence a feature of this invention is its adaptability to the requirements of the location in which it is to be installed.

As previously mentioned, in alternative designs the device can incorporate hydraulic mechanisms as alternatives to torsion springs <NUM> said hydraulic mechanisms designed to force the centre plate <NUM> or pan-shaped section back to its original position following a movement cycle wherein the centre plate <NUM> or pan-shaped section has been displaced as shown in <FIG> and then returned to the position shown for example in <FIG>, <FIG> or another position wherein the centre plate <NUM> returns to rest on the flat surface <NUM> of the opposing frame <NUM>.

Another embodiment of the expansion joint cover is shown in <FIG> inclusive wherein the centre plate <NUM> can comprise a pan-shaped section which can be infilled with finishes of varying types such as paving tiles, resins, coatings and wall cladding materials.

<FIG> shows a sectional detail of a Type <NUM> device wherein the centre plate shown in <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and <FIG> has been replaced by a pan system <NUM> into which an infill <NUM> such as paving, cladding or other materials may be installed. This both increases the load capacity and reduces the visual impact of the expansion joint cover. The pan <NUM> spans the expansion gap <NUM>. In this form the device comprises a central pan <NUM> with outward sloping ends and a central recess for the installation of varying types of finish <NUM>. The ends of the central pan <NUM> may alternatively extend at <NUM> degrees from the pan base. The expansion joint cover is fixed to the respective substrates <NUM> either side of the expansion gap <NUM> by means of screw or bolt fixings <NUM> and these fixings transfer movement forces within the structure to the expansion joint cover.

<FIG> shows a frame <NUM> fixed with said screws and bolts wherein the face of this frame that points inwards towards the expansion gap <NUM> slopes outwards. The outer face of the central pan <NUM> also slopes outwards such that the angles of both slopes are approximately the same.

<FIG> also shows an arm <NUM> that extends from the base of the pan <NUM> where this arm <NUM> entraps a roller mechanism or seal <NUM>. The combination of the arm <NUM> and roller mechanism or seal <NUM> serve to both allow the device to move smoothly when the expansion gap <NUM> opens and closes and also allow an amount of vertical deflection between the levels of the substrate on one side of the expansion gap <NUM> to the substrate on the other side. The roller mechanism or seal <NUM> slides on a flat surface <NUM> of the frame <NUM>.

<FIG> shows that a gap <NUM> has been left between the frame <NUM> and the sloping face of the central pan <NUM>. This gap <NUM> can vary in width and is designed to accommodate 'normal deflections' of the structure such that it allows the expansion gap <NUM> to close until the outward sloping face of the central pan <NUM> touches the sloping face of the opposing frame <NUM>.

In <FIG> the gap <NUM> incorporates a backer rod <NUM> made from a flexible material such as foam polyethylene topped by a sealant <NUM> which is used to accommodate movement and prevent the ingress of water, dirt and other contaminants. A further backer rod <NUM> and seam of sealant <NUM> is installed on the opposite side of the pan system for similar reasons.

In <FIG> the lower frame <NUM> is affixed to the substrate <NUM> by screws or bolts <NUM>. This frame <NUM> having C-shaped retainers <NUM> and <NUM> into which barbell shaped sections <NUM> and <NUM> are inserted said barbell-shaped sections <NUM> and <NUM> incorporating torsion springs or hydraulic mechanisms and these being further attached by C-shaped retainers <NUM> and <NUM> to the central pan <NUM>. The C-shaped retainers <NUM>, <NUM>, <NUM> and <NUM> being designed to entrap the ends of the barbell shaped sections <NUM> and <NUM> whilst at the same time allowing them to rotate in response to pressure on the sloping outer faces of the central pan <NUM> by the sloping face of the opposing frame <NUM> when the expansion gap <NUM> closes sufficiently.

<FIG> is a sectional view of the Type <NUM> device after the expansion gap <NUM> has opened in response to 'normal deflection' where the substrates <NUM> withdraw and either frame <NUM> thereby increasing width of the expansion gap <NUM>. The width of the central pan <NUM> may be tailored to accommodate the maximum expected opening movement of the expansion gap <NUM> whether such movement arises from 'normal deflection' or 'seismic deflection. In <FIG> it may be seen that the gap <NUM> between the outer frame <NUM> and the pan <NUM> has opened in response to the 'normal deflection' such that the seam of sealant <NUM> has been stretched.

<FIG> displays the Type <NUM> device following 'seismic deflection' wherein the expansion gap <NUM> has opened to its full extent and the central pan <NUM> has withdrawn opening a gap <NUM> between the face <NUM> of the central pan and the outer frame <NUM>. This smooth operation of this action is aided by the roller/seal <NUM> sliding on the flat surface <NUM>. In this instance the seam of sealant that had been inserted between the central pan <NUM> and the outer frame <NUM> is sacrificial has failed and, as a consequence has been eliminated from this drawing. The seam of sealant <NUM> and foam backer rod <NUM> remain in place.

<FIG> depicts a situation where the expansion gap <NUM> has closed in response to 'normal deflection' movement and the sloping face of the central pan <NUM> meets the sloping face <NUM> of the central pan <NUM>. This closure has forced the sealant and backer rod from the space between the central pan and the outer frame. In this instance the sealant has been ejected from the gap between the frames and has been omitted from the figure.

<FIG> depicts the Type <NUM> expansion joint cover in a situation where the expansion gap <NUM> has closed in response to 'seismic deflection' movement to an extent greater than 'normal deflection' such as during a earthquake wherein the sloping face <NUM> of the central pan <NUM> comes into contact with the sloping face <NUM> of the opposing frame <NUM> and the central pan <NUM> is forced upwards causing the barbell shaped sections <NUM> and <NUM> to rotate upwards thereby lifting the central pan <NUM> whilst ensuring that it remains parallel with the plane of both the lower frame <NUM> and the opposite frame <NUM>. Further closure of the expansion gap <NUM> causes the central pan <NUM> to extend over and beyond the top of the opposing frame <NUM> and across the surface of the abutting substrate <NUM>. This smooth operation of this action is aided by the roller/seal <NUM> which is fitted within an extension <NUM> of the central pan <NUM>. In this type of seismic deflection event the seams of sealant and backer rods which had been inserted either side of the central pan <NUM> are sacrificial have failed and have been eliminated from this drawing.

Another embodiment of the expansion joint cover in accordance with the present teachings is shown in <FIG>. This embodiment is similar to the Type <NUM> device except that a different configuration is provided for the seals used between each section of the frame and the centre pan.

<FIG> shows a sectional detail of the Type <NUM> device wherein the centre plate shown in <FIG>, <FIG>, <FIG>, <FIG> has been replaced by a pan system <NUM> into which an infill <NUM> such as paving, cladding or other materials may be installed. This allows an increase in the load capacity and reduces the visual impact of the expansion joint cover. The pan <NUM> spans the expansion gap <NUM>. In this form the device comprises a central pan <NUM> with outward sloping ends said ends having recesses <NUM> and <NUM> which are designed to engage with pre-extruded flexible seals <NUM> and <NUM>. The ends of the central pan <NUM> may alternatively extend at <NUM> degrees from the pan base. The expansion joint cover is fixed to the respective substrates by means of screw or bolt fixings and these fixings transfer movement forces within the structure to the expansion joint cover.

<FIG> shows an outer frame <NUM> fixed with said screws and bolts wherein the lower face of this frame <NUM> points inwards towards the expansion gap <NUM> and thereafter slopes outwards having a recess <NUM> at the uppermost point of the frame <NUM> wherein this recess is used to entrap the ends of a pre-extruded seal <NUM>. The outer face of the central pan <NUM> also slopes outwards such that the angles of both slopes are approximately the same.

<FIG> also shows an arm <NUM> that extends from the base of the pan <NUM> where this arm <NUM> entraps a roller mechanism or seal <NUM>. The combination of the arm <NUM> and roller mechanism <NUM> serve to both allow the device to move smoothly on the flat surface <NUM> of the frame when the expansion gap <NUM> opens and closes and also allow an amount of vertical deflection between the level of the substrate on one side of the expansion gap <NUM> to the substrate on the other side.

<FIG> shows that a gap <NUM> has been left between the frame <NUM> and the sloping face of the central pan <NUM>. This gap <NUM> can vary in width and is designed to accommodate 'normal deflections' of the structure such that it allows the expansion gap <NUM> to close until the outward sloping face of the central pan <NUM> touches the sloping face of the opposing frame <NUM>. This closing movement serves to accommodate deflections arising from 'normal deflection' forces.

In <FIG> the gap <NUM> is closed at the surface by means of a seal <NUM> the ends of which are inserted into the recess <NUM> of the outer frame <NUM> and on the other side of the gap <NUM> the ends of the seal are fitted into the recess <NUM> of the central pan <NUM>. A further seal <NUM> is installed on the opposite side of the pan system <NUM> wherein the ends of this seal <NUM> are inserted into the recess <NUM> of the lower frame <NUM> and the recess <NUM> of the central pan <NUM>.

In <FIG> the lower frame <NUM> is affixed to the substrate by screws or bolts this frame <NUM> having C-shaped retainers <NUM> and <NUM> into which barbell shaped sections <NUM> and <NUM> are inserted said barbell-shaped sections <NUM> and <NUM> incorporating torsion springs or hydraulic mechanisms and these being further attached by C-shaped retainers <NUM> and <NUM> to the central pan <NUM>. The C-shaped retainers <NUM>, <NUM>, <NUM> and <NUM> being designed to entrap the ends of the barbell shaped sections <NUM> and <NUM> whilst at the same time allowing them to rotate in response to pressure on the sloping outer faces of the central pan <NUM> by the sloping face of the outer frame <NUM> when the expansion gap <NUM> closes sufficiently.

<FIG> is a sectional view of the Type <NUM> device after the expansion gap <NUM> has opened in response to 'normal deflection'. In this figure the gap <NUM> between the outer frame <NUM> and the central pan <NUM> has opened by a similar amount to that of the expansion gap <NUM> such that the seal <NUM> has been stretched to accommodate the movement. The width of the central pan <NUM> may be tailored to accommodate the maximum expected opening movement of the expansion gap <NUM> whether such movement arises from 'normal deflection' or 'seismic deflection'. In this instance one of the pre-extruded elastomeric seals has been stretched.

<FIG> is a sectional view of the Type <NUM> device after the expansion gap <NUM> has opened in response to 'seismic deflection'. In this figure the gap <NUM> between the outer frame <NUM> and the central pan <NUM> has opened to such an extent that the pre-extruded flexible seal that was fitted between the outer frame <NUM> and the central pan <NUM> has failed and hence has been omitted from this drawing.

<FIG> show the Type <NUM> in a situation where the expansion gap <NUM> has closed in response to 'normal deflection' and where the gap <NUM> has similarly closed in response to such movement resulting compression of the seal <NUM>.

<FIG> depicts the Type <NUM> in a situation where the expansion gap <NUM> has closed in response to 'seismic deflection' to an extent greater than 'normal deflection' such as during an earthquake wherein the sloping face <NUM> of the central pan <NUM> comes into contact with the sloping face <NUM> of the outer frame <NUM> and the central pan <NUM> is forced upwards causing the barbell shaped sections <NUM> and <NUM> to rotate as shown upwards thereby lifting the central pan <NUM> whilst ensuring that it remains parallel with the base plane of both the lower frame <NUM> and the outer frame <NUM>. Further closure of the expansion gap <NUM> causes the central pan <NUM> to extend over and beyond the top of the opposing frame <NUM> and across the surface of the abutting substrate <NUM>. The seals which were installed on either side of the central pan <NUM> are sacrificial, have failed and are omitted from this drawing.

Another embodiment of the expansion joint cover in accordance with the present teachings is shown in <FIG>. This embodiment is similar to the Type <NUM> and Type <NUM> devices except that instead of seals, wings or flange are connected to the centre pan and these contact the frame at each side of the centre pan.

<FIG> shows a sectional detail of a Type <NUM> device wherein the centre plate shown in <FIG>, <FIG>, <FIG>, <FIG> has been replaced by a pan system <NUM> into which an infill <NUM> such as paving, cladding or other materials may be installed. The pan <NUM> spans the expansion gap <NUM>. In this form the device comprises a central pan <NUM> with one outward sloping end <NUM> said end having a recess <NUM> into which a flange or wing section <NUM> is installed. At the other end of the central pan <NUM> a similar recess <NUM> has been formed in the end of the section said recess being used for the installation of a flange or wing <NUM>.

In <FIG> the gap <NUM> is closed at the surface by means of a preferably metal or rigid plastic arm <NUM> wherein this section spans the gap <NUM> such that it overhangs the flat surface <NUM> of the outer frame <NUM>. The end of the arm <NUM> is engaged in the recess <NUM> such that is forms a hinge which is described in greater detail in <FIG>. At the other end of the central pan <NUM> a further hinged metal or rigid plastic arm <NUM> is installed within the recess <NUM> of the central pan <NUM> wherein this section spans the flat upper part of the lower frame <NUM>.

The sloped end <NUM> of the central pan <NUM> may alternatively extend at <NUM> degrees from the pan base. The expansion joint cover is fixed to the respective substrates by means of screw or bolt fixings and these fixings transfer movement forces within the structure to the expansion joint cover.

<FIG> shows an outer frame <NUM> fixed with said screws and bolts wherein the lower face of this frame <NUM> points inwards towards the expansion gap <NUM> and thereafter slopes outwards. The top surface <NUM> of this frame <NUM> is substantially flat except for a sloping upstand <NUM> at the end of the section. The outer face <NUM> of the central pan <NUM> also slopes outwards such that the angles of both slopes are approximately the same.

<FIG> also shows an arm that extends from the base of the pan <NUM> where this arm entraps a roller mechanism or seal <NUM>. Again, this slides on a flat surface <NUM> of the frame. The combination of the arm and roller mechanism <NUM> serve to both allow the device to move smoothly when the expansion gap <NUM> opens and closes and also allow an amount of vertical deflection between the level of the substrate on one side of the expansion gap <NUM> to the substrate on the other side.

<FIG> shows that a gap <NUM> has been left between the outer frame <NUM> and the sloping face of the central pan <NUM>. This gap <NUM> can vary in width and is designed to accommodate 'normal deflections' of the structure such that it allows the expansion gap <NUM> to close until the outward sloping face of the central pan <NUM> touches the sloping face of the outer frame <NUM>. The dimensions of the gap <NUM> are normally mirrored by the distance between the end <NUM> of the flange or wing <NUM> and the beginning of the upstand <NUM> of the outer frame <NUM>. These equal dimensions allow closing movement which serves to accommodate deflections arising from 'normal deflection' forces.

<FIG> is a sectional view of the Type <NUM> device after the expansion gap <NUM> has opened in response to 'normal deflection'. In this figure the gap <NUM> between the outer frame <NUM> and the central pan <NUM> has opened by a similar amount to that of the expansion gap <NUM> such that the flange or wing <NUM> has been withdrawn across the flat upper surface <NUM> of the outer frame <NUM> to accommodate the movement. The width of the central pan <NUM> and the flange or wing <NUM> may be tailored to accommodate the maximum expected opening movement of the expansion gap <NUM> whether such movement arises from 'normal deflection' or 'seismic deflection'.

<FIG> represents the Type <NUM> device after the expansion gap <NUM> has opened in response to 'seismic deflection'. In this figure the gap <NUM> between the outer frame <NUM> and the central pan <NUM> has opened by a similar amount to that of the expansion gap <NUM> such that the flange or wing <NUM> has been withdrawn across the flat upper surface <NUM> of the outer frame <NUM> to accommodate the movement. In this situation the end <NUM> of the flange or wing <NUM> can rotate downwards until it touches the sloping face of the outer frame <NUM>. The width of the central pan <NUM> and the flange or wing <NUM> may be tailored to accommodate the maximum expected opening movement of the expansion gap <NUM> whether such movement arises from 'normal deflection' or 'seismic deflection'.

<FIG> is a sectional view of the Type <NUM> device after the expansion gap <NUM> has closed in response to 'normal deflection. In this figure the gap <NUM> between the outer frame <NUM> and the outer face of the central pan <NUM> has closed by a similar amount to that of the expansion gap <NUM> such that the flange or wing <NUM> has been moved across the flat surface <NUM> of the outer frame <NUM> until it touches the sloping edge <NUM> of the outer frame <NUM>. The width of the central pan <NUM> and flange or wing <NUM> may be tailored to accommodate the maximum expected opening movement of the expansion gap <NUM> whether such movement arises from 'normal deflection' or 'seismic deflection.

<FIG> depicts the Type <NUM> device in a situation where the expansion gap <NUM> has closed in response to structural movement to an extent greater than 'normal deflection' such as during a seismic event wherein the sloping face <NUM> of the central pan <NUM> comes into contact with the sloping face <NUM> of the outer frame <NUM> and the central pan <NUM> is forced upwards causing the barbell shaped sections <NUM> and <NUM> to rotate as shown thereby lifting the central pan <NUM> whilst ensuring that it remains parallel with the plane of the base of both the lower frame <NUM> and the outer frame <NUM>. Further closure of the expansion gap <NUM> causes the central pan <NUM> to extend over and beyond the top of the opposing frame <NUM> and across the surface of the abutting substrate <NUM>. As the central pan <NUM> lifts the flanges or wings <NUM> and <NUM> rotate within the sockets <NUM> and <NUM> such that the ends of these flanges or wings touch the finishes <NUM> and <NUM> thereby forming ramps at either side of the central pan. These ramps facilitate the passage of people across the expansion joint cover during and following a seismic event. As can be seen, the central pan has been forced upwards and when used in a flooring application the metal flanges or wings fold downwards under the force of gravity creating a ramp which aids the passage of pedestrians and wheeled vehicles passing across an expansion joint cover.

<FIG> shows a sectional view of one type of flange for use with the device in accordance with the present teachings where it connects to the central pan forming a hinge which can pivot to form a ramp and thereby aid the passage of pedestrians and wheeled vehicles passing across an expansion joint cover installed in a floor. It will be appreciated that this configuration is merely exemplary. The person skilled in the art can choose any type of hinge structure as long as the wings or arms can move freely downwards (or towards the frame) as described herein.

In particular, <FIG> shows a typical detail of the rigid hinged flanges or wings <NUM> and <NUM> represented in <FIG>, <FIG>. This figure comprises two drawings wherein the top drawing presents the end of a central pan <NUM> with a circular recess <NUM> which is greater than <NUM> degrees into which the largely circular end <NUM> of the arm <NUM> has been inserted. The flange <NUM> of the central pan section <NUM> and the upstand <NUM> of the flange or wing <NUM> limit the magnitude of rotation that the arm <NUM> can exhibit in one rotational direction whilst the end <NUM> of the central pan <NUM> limits the rotation of the arm <NUM> in the other direction.

<FIG> shows the flange or wing in two positions where the upper drawing displays the flange or wing <NUM> in its position during phases of 'normal deflection' as shown in <FIG> wherein the upstand <NUM> meets the edge <NUM> of the central pan thereby maintaining the position of the flange or wing <NUM> parallel with the surface of the central pan. The lower drawing shows the flange or wing <NUM> in a sloping position such as may be experienced during a seismic event where the central pan is forced upwards as described in <FIG> and <FIG>. The magnitude of rotation is limited to the point where the lower face of the flange or wing <NUM> touches the outer edge <NUM> of the end of the central pan <NUM>.

As noted earlier within some structures items such as services, acoustic suppression materials, fire barriers, waterproofing membranes and other devices may be incorporated within an expansion gap provided the gap is wide enough to accommodate anticipated deflection and not impact the items installed within said expansion gap. As a result, it may be desirable to inspect these items periodically and most particularly after a seismic event to determine whether they have remained unaffected or need to be replaced. The normal method of achieving this is to remove the entire expansion joint cover and in doing so abutting finishes are often compromised and must be replaced. Ideally only the central plate or pan would be removed, inspection and where required repairs or replacement of affected parts undertaken, and the central pan or plate replaced afterwards.

<FIG> show another embodiment of the expansion joint cover in accordance with the present teachings, which meets this need to remove the central pan. In particular, <FIG> inclusive show a version of the device where the central pan can be removed to facilitate inspection of the expansion gap without affecting abutting finishes. Similarly when the central pan has been removed any components or materials located within the expansion gap can be repaired or replaced as required. It should be appreciated that while the embodiment of <FIG> is shown with respect to the pan configuration of <FIG> (Type <NUM> device), this is merely exemplary and any of the centre pan configurations shown herein are compatible with the embodiment of <FIG>.

<FIG> shows a lower frame <NUM> which includes C-shaped recesses <NUM> and <NUM> for the entrapment of the ends of barbell-shaped sections <NUM> and <NUM> said barbell-shaped sections being further attached by C-shaped retainers <NUM> and <NUM> formed in an upper plate <NUM>. A centre pan may be affixed to the upper plate <NUM>. The barbell sections <NUM> and <NUM> may optionally comprise solid formed metal sections, torsion springs or hydraulic components and serve to rotate under 'seismic deflection' raising any affixed centre pan above the level of abutting substrates thereby allowing any expansion gap to fully close. The torsion springs or hydraulic components force the affixed central pan to return to its normal position following a full closing and opening movement cycle. <FIG> also disclosed an upstanding section with an overhang <NUM>.

<FIG> shows a central pan <NUM> which has been designed to be affixed to the device disclosed in <FIG>. This central pan comprises a frame <NUM> with a recess into which an infill <NUM> such as paving, cladding or other materials may be installed. Substantially this pan is like the central pan shown and described as Type <NUM> in earlier drawings. In this iteration the central pan has an L-shaped flange <NUM> which extends from one face of the pan and a sloped face <NUM> extending from the opposite face. An arm or extension <NUM> contains a recess <NUM> into which a roller or seal may be installed.

<FIG> shows where the components described in <FIG> are fixed together. The pan <NUM> containing an infill <NUM> has been affixed to the assembly described in <FIG> by means of bolts and nuts <NUM> such that these fixings are hidden within the infill <NUM>. Alternatively, the central pan <NUM> may be fixed to the underlying device described in <FIG> by means of countersink head machine screws fixed through the upper surface <NUM> of the L-shaped flange and into the upper frame <NUM> as explained in more detail hereinafter.

<FIG> shows the first step in removal of the central pan wherein the central pan <NUM> has been levered upwards causing the barbell shaped components <NUM> to rotate lifting the pan <NUM> above the level of the abutting finishes <NUM>. L-shaped braces are then engaged within the upper frame while resting on abutting finishes such that the central pan and upper frame are secured in place. In this position a device such as an angled piece of metal <NUM> can be inserted into the inverted U-channel of the upper frame <NUM> such that the central pan <NUM> is fixed in this position. The nuts on the ends of the bolts shown as <NUM> in <FIG> can then be removed and the central pan lifted out of position as shown in <FIG>. It should be noted that while the bolts and nuts <NUM> are not shown in <FIG>, these are still present. They are simply removed from this figure for improved visibility.

<FIG> shows a situation where the bolts securing the central pan to the upper frame have been removed wherein the central pan can be lifted out of position revealing the expansion gap and allowing inspection, repair or replacement of any components located within said expansion gap. Once this inspection has been completed then the central pan can be replaced, the L-shaped brace removed, and the joint returned to its normal position.

It should also be noted that this system also allows the central pan to be replaced in the event of damage or in instances where 'seismic deflection' has occurred and the either the expansion joint cover has been lifted out of the gap and not returned to its normal position lying flush with surface of abutting finishes or the gap has opened substantially such that the space between the edge of the outer frame and the central pan are unacceptable due to either aesthetic or functional reasons. In this instance a narrower or wider central pan or plate can be installed without affecting surrounding finishes.

<FIG> shows an alternative means of fixing the central pan <NUM> to the underlying composite frame noted in <FIG> wherein the central pan <NUM> with an infill <NUM> has been attached to the underlying composite frame by means of countersink machine screws <NUM> fitted through the L-shaped flange of the central pan <NUM>. In this design these screws are visible and accessible from the surface of the device rather than hidden as shown in <FIG>.

<FIG> shows an iteration of the device where the modified central pan noted in <FIG> has been fixed with a machine screw from the surface to the underlying upper frame. This shows a modified version of the lower frame <NUM> shown in <FIG>. In this version the lower frame is connected via barbell shaped sections to an upper frame described in <FIG> which has been adapted so that a centre plate or pan can be removed to accommodate inspection of the expansion gap.

<FIG> shows the machine screw being removed from the device displayed in <FIG> and the central pan being removed.

It will be appreciated that while this configuration of figures is <NUM> and <NUM> is described with respect to the Type <NUM> device, this configuration can be used in conjunction with a any central pan or central plate as outlined in more detail hereinafter.

<FIG> displays the means by which the central pan <NUM> with its infill <NUM> can be removed from the composite frame <NUM> without having to lever the central pan or plate upwards thereby making removal of said pan simpler to remove and replace when compared to the procedure shown in <FIG> and <FIG>. The fixing screws <NUM> are removed releasing the central pan from the underlying composite frame <NUM> with the only drawback being that said fixing screws are visible in the surface of the device.

The configuration described with respect to <FIG> is applicable to any of the previous embodiments. For example, with respect to the Type <NUM> device, the countersink machine screws can be inserted through the surface of the central plate. This is shown with respect to <FIG> and described in more detail below.

Turning to <FIG>, more details of how the expansion joint cover in accordance with the present teachings functions are provided. As the central pan or plate is fixed to only one side of the substrate its ability to accommodate movement in the shear plane is therefore theoretically unlimited however movement vertical to the plane of the joint is limited by the length of the barbells units <NUM> and <NUM> as is shown in <FIG>. In this instance the Type <NUM> device design shown in <FIG>, <FIG>, <FIG>, <FIG> is used for illustrative purposes.

In <FIG> the two substrates either side of the expansion gap <NUM> have been denoted as A and B respectively. In this illustration deflection of the structure has lifted side A (or side B has lowered) such that the central pan <NUM> has been forced upwards whilst the composite frame <NUM> to which it is attached remains in its former position. The attachment of the central pan <NUM> to the composite frame <NUM> causes a drag on the roller/seal <NUM> moving it to the position denoted as <NUM>. As a result, the barbell shaped linkages <NUM> and <NUM> rotate upwards. The flange or wing <NUM> fitted to the central pan <NUM> rotates downward under the force of gravity creating a ramp which aids the passage of people or vehicles across the expansion gap cover.

<FIG> illustrates the situation where the other side B of the substrate lifts. In this event the entire central pan <NUM> which is fixed to the composite frame rises in response to the vertical deflection such that it is cantilevered above the substrate A. The flange or wing <NUM> fitted to the central pan <NUM> rotates downward under the force of gravity creating a ramp which aids the passage of people across the device.

In <FIG>, the Type <NUM> device of <FIG> is shown responding to vertical movements in the substrate. <FIG> shows another embodiment of the present teachings similar to the Type <NUM> device but which can better accommodate vertical movement of the substrate. In particular, <FIG> shows a variation of the device as shown in <FIG> inclusive wherein a central plate rather than a central pan as shown in <FIG>. In <FIG>, the expansion gap cover comprises a central plate with flanges or wings similar to those illustrated in <FIG> inclusive and in <FIG>.

<FIG> shows an outer frame <NUM> fixed with screws to a substrate wherein a lower plate <NUM> of this frame <NUM> extends towards the expansion gap <NUM>. This lower plate also has a sloped section which extends upward to a top plate or top surface. The top surface of this frame <NUM> is substantially flat save for a sloping upstand at the end of the section. An outer face of the central plate <NUM> also slopes outwards such that the angles of both slopes are approximately the same and the faces are substantially parallel.

<FIG> also shows an arm <NUM> that extends from the base of the centre plate <NUM> where this arm entraps a roller mechanism or seal <NUM>. The combination of the arm and roller mechanism <NUM> serve to both allow the device to move smoothly when the expansion gap <NUM> opens and closes and also allow an amount of vertical deflection between the level of the substrate on one side of the expansion gap <NUM> to the substrate on the other side.

<FIG> shows that a gap <NUM> has been left between the outer frame <NUM> and the sloping face of the central pan <NUM>. This gap <NUM> can vary in width and is designed to accommodate 'normal deflections' of the structure such that it allows the expansion gap <NUM> to close until the outward sloping face of the central pan <NUM> touches the sloping face of the outer frame <NUM>. The dimensions of the gap <NUM> are normally mirrored by the distance between the end of the flange or wing <NUM> and the beginning of the upstand of the outer frame <NUM>. These equal dimensions allow closing movement which serves to accommodate deflections arising from 'normal deflection' forces.

<FIG> is a sectional view of the expansion gap cover of <FIG> after the expansion gap <NUM> has closed in response to 'normal deflection. In this figure the gap <NUM> between the outer frame <NUM> and the outer face of the centre plate <NUM> has closed by a similar amount to that of the expansion gap <NUM> such that the flange or wing <NUM> has been moved across the flat surface of the outer frame <NUM> until it touches the sloping edge of the outer frame <NUM>. The width of the centre plate <NUM> and flange or wing <NUM> may be tailored to accommodate the maximum expected opening movement of the expansion gap <NUM> whether such movement arises from 'normal deflection' or 'seismic deflection.

<FIG> depicts the expansion joint cover of this embodiment in a situation where the expansion gap <NUM> has closed in response to structural movement to an extent greater than 'normal deflection' such as during a seismic event wherein the sloping face of the central pan <NUM> comes into contact with the sloping face of the outer frame <NUM> and the centre plate <NUM> is forced upwards causing the barbell shaped sections <NUM> and <NUM> to rotate as shown thereby lifting the central pan <NUM> whilst ensuring that it remains parallel with the plane of the base of both the lower frame and the outer frame <NUM>. Further closure of the expansion gap <NUM> causes the centre plate <NUM> to extend over and beyond the top of the opposing frame <NUM> and across the surface of the abutting substrate. As the centre plate <NUM> lifts the flanges or wings <NUM> and <NUM> rotate within their sockets such that the ends of these flanges or wings touch the finishes thereby forming ramps at either side of the centre plate. These ramps facilitate transit across the expansion joint cover during and following a seismic event.

<FIG> is a sectional view of the expansion joint cover of this embodiment after the expansion gap <NUM> has opened in response to 'normal deflection'. In this figure the gap <NUM> between the outer frame and the centre plate has opened by a similar amount to that of the expansion gap <NUM> such that the flange or wing <NUM> has been withdrawn across the flat upper surface of the outer frame to accommodate the movement. The width of the central pan and the flange or wing <NUM> may be tailored to accommodate the maximum expected opening movement of the expansion gap <NUM> whether such movement arises from 'normal deflection' or 'seismic deflection'.

<FIG> represents the expansion joint cover of this embodiment after the expansion gap <NUM> has opened in response to 'seismic deflection'. In this figure the gap <NUM> between the outer frame <NUM> and the centre plate <NUM> has opened by a similar amount to that of the expansion gap <NUM> such that the flange or wing <NUM> has been withdrawn across the flat upper surface of the outer frame <NUM> to accommodate the movement. In this situation the end of the flange or wing <NUM> can rotate downwards until it touches the sloping face of the outer frame <NUM>. The width of the central pan <NUM> and the flange or wing <NUM> may be tailored to accommodate the maximum expected opening movement of the expansion gap <NUM> whether such movement arises from 'normal deflection' or 'seismic deflection'.

In addition, while a roller is provided in the embodiment of <FIG> for sliding on surface <NUM>, this is not essential. A similar configuration to that of <FIG> could be employed wherein the flat plate slides on a protruding tongue.

As previously mentioned, the configuration described with respect to <FIG> is also applicable to the Type <NUM> device. That is, in such an embodiment of the expansion joint cover, the centre plate can be removed. <FIG> shows a means of fixing the centre plate <NUM> to the underlying composite frame <NUM> as noted in <FIG> wherein the centre plate <NUM> has been attached to the underlying composite frame <NUM> by means of countersink machine screws <NUM> fitted through the centre plate <NUM> and thereby securing it to the underlying composite frame <NUM>. In this design these screws are visible and accessible from the surface of the device allowing the centre plate to be removed to permit inspection of the expansion gap <NUM>. While, wings or flanges <NUM> are shown in <FIG>, these are optional and a configuration similar to the Type <NUM> device without such wings <NUM> may be used in conjunction with the removal plate configuration of <FIG>.

It will also be appreciated by the person skilled in the art that a variation of the design of <FIG> may employ the seals shown with respect to <FIG>. That is, the seals can also be used in conjunction with the flat central plate and are not restricted to the central pan embodiments. It will also be understood that the Type <NUM> device may employ the aforementioned seals (<FIG>) or wings (<FIG>) regardless of whether the plate is configured to be removable or not.

<FIG> shows a sectional detail of the Type <NUM> device wherein the centre plate shown in <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and <FIG> has been replaced by a pan system <NUM> into which an infill <NUM> such as paving, cladding or other materials may be installed. This both increases the load capacity and reduces the visual impact of the expansion joint cover. The pan <NUM> spans the expansion gap <NUM>. In this form the device comprises a central pan <NUM> with outward sloping ends and a central recess for the installation of varying types of finish <NUM>. The ends of the central pan <NUM> may alternatively extend at <NUM> degrees from the pan base. The expansion joint cover is fixed to the respective substrates <NUM> either side of the expansion gap <NUM> by means of screw or bolt fixings <NUM> and these fixings transfer movement forces within the structure to the expansion joint cover.

<FIG> shows that a gap <NUM> has been left between the frame <NUM> and the sloping face of the central pan <NUM>. This gap <NUM> can vary in width and is designed to accommodate 'normal deflections' of the structure such that it allows the expansion gap <NUM> to close until the outward sloping face of the central pan or plate <NUM> touches the sloping face of the opposing frame <NUM>.

<FIG> includes a further innovative step wherein two protrusions, semi-circular elements <NUM> and <NUM>, are shown. The first semi-circular element <NUM> is shown attached or adjacent to the end of outer frame <NUM> wherein <NUM> may be considered as an integral part of said frame or as a separate component abutting or separate from the outer frame <NUM>. Similarly, a semi-circular element <NUM> is attached to the base of the central pan <NUM> in a position such that the distance <NUM> between the sloping surfaces of the outer frame <NUM> and central pan <NUM> is equal to the distance <NUM> between the semi-circular elements <NUM> and <NUM>. When the expansion gap <NUM> closes the sloping faces of the outer frame <NUM> and central pan <NUM> touch at the same time as the semi-circular elements <NUM> and <NUM> meet. This feature is introduced for two reasons:.

It should be appreciated by the person skilled in the art that both protrusions <NUM> and <NUM> do not have to be provided to the expansion joint cover and the expansion joint cover may comprise only one as deemed appropriate.

In <FIG> and further illustrations the protrusions or elements <NUM> and <NUM> have been shown as being semi-circular components; this is for illustration purposed and said elements could be formed as sloping angles or other shaped forms.

<FIG> is a sectional view of embodiments of the device described in <FIG> after the expansion gap <NUM> has opened in response to 'normal deflection' where the substrates <NUM> withdraw and either or both frames <NUM> and <NUM> retracted thereby increasing width of the expansion gap <NUM>. The width of the central pan <NUM> may be tailored to accommodate the maximum expected opening movement of the expansion gap <NUM> whether such movement arises from 'normal deflection' or 'seismic deflection. In <FIG> it may be seen that the gap <NUM> between the outer frame <NUM> and the pan <NUM> has opened in response to the 'normal deflection' such that the seam of sealant <NUM> has been stretched.

<FIG> displays the device described in <FIG> following 'seismic deflection' wherein the expansion gap <NUM> has opened to its full extent and the central pan <NUM> has withdrawn opening a gap <NUM> between the face <NUM> of the central pan and the outer frame <NUM>. This smooth operation of this action is aided by the roller/seal <NUM> sliding on the flat surface of the outer frame <NUM>. In this instance the seam of sealant that had been inserted between the central pan <NUM> and the outer frame <NUM> is sacrificial has failed and, as a consequence has been eliminated from this drawing. The seam of sealant <NUM> and foam backer rod <NUM> remain in place.

<FIG> depicts a situation where the expansion gap <NUM> has closed in response to 'normal deflection' movement and the sloping face of the central pan or plate <NUM> meets the sloping face of the outer frame <NUM>. This closure has forced the sealant and backer rod from the space between the central pan and the outer frame such that there is no gap <NUM> between these two components. In this instance the sealant has been ejected from the gap between the frames and has been omitted from the figure.

<FIG> also shows that following 'normal closing deflection' the semi-circular elements <NUM> and <NUM> come into contact as <NUM> demonstrates. Hence the central pan or plate <NUM> is in contact with the outer frame <NUM> at points indicated by <NUM> and <NUM>.

<FIG> depicts a situation where the expansion gap <NUM> has closed in response to movement greater than 'normal deflection' and the sloping face of the central pan <NUM> has met the sloping face <NUM> of the outer frame <NUM> serving to lift the central pan <NUM> above the level of the finishes <NUM> such that the central pan <NUM> lies above the level of said finishes <NUM> by a distance indicated as <NUM>. In addition, the radiused sections <NUM> and <NUM> formed at the end of the outer frame <NUM> and base plate of the central pan <NUM> come into contact and assist in forcing the central pan upwards. This action has in turn caused to barbell shaped units <NUM> and <NUM> to rotate upwards to accommodate the lifting forces being exerted upon the central pan <NUM>. This closure has forced the sealant and backer rod from the space between the central pan and the outer frame. In this instance the sealant has been ejected from the gap between the frames and has been omitted from the figure.

<FIG> depicts the Type <NUM> expansion joint cover in a situation where the expansion gap <NUM> has closed in response to 'seismic deflection' movement to an extent greater than 'normal deflection' such as during an earthquake wherein the sloping face <NUM> of the central pan <NUM> comes into contact with the sloping face <NUM> of the opposing frame <NUM> and the central pan <NUM> is forced upwards causing the barbell shaped sections <NUM> and <NUM> to rotate upwards thereby lifting the central pan <NUM> whilst ensuring that it remains parallel with the plane of both the lower frame <NUM> and the opposite frame <NUM>. Further closure of the expansion gap <NUM> causes the central pan <NUM> to extend over and beyond the top of the opposing frame <NUM> and across the surface of the abutting substrate <NUM>. This smooth operation of this action is aided by the roller/seal <NUM> which is fitted within an extension <NUM> of the central pan <NUM>. In this type of seismic deflection event the seams of sealant and backer rods which had been inserted either side of the central pan <NUM> are sacrificial have failed and have been eliminated from this drawing.

While the embodiments described herein include a frame section with multiple C-shaped retainers into which barbell shaped sections <NUM> and <NUM> are inserted and said barbell-shaped sections being further attached by C-shaped retainers to a centre plate or pan, the present teachings are not limited to such a configuration. Any type of connector may be used in place of the C-shaped retainers. Furthermore any type of linkage section may be used in place of the barbell-shaped section. For example, although the C-shaped retainers may be considered female connectors with the barbell-shaped section including male connectors for insertion in the female connectors, this does not have to be the case. The frame and centre plate/pan may be fitted with male connectors and the linkage fitted with female connectors. Many other configurations can be envisioned as long as the linkage sections pivot within the connectors to allow movement of the centre section (plate or pan) with respect to the frame section to which it is attached. In particular, the linkage section and connectors must allow the centre section (pan or plate) to remain parallel with the frame even after it moves vertically away from the frame.

It will be appreciated that the teachings described herein provide a significant improvement on the prior art central pan and centring bar systems by eliminating the need for centring bars.

The teachings described herein also provide significant improvement on the prior art hinge type systems by providing an expansion joint cover which doesn't present a trip hazard in floors as following closing movement its top surface lies parallel to the floor plane and meets current disability legislation. Similarly, this accommodates the passage of differing vehicle types.

When used in walls the expansion joint cover described herein does not expose the expansion gap to the elements and as it lies parallel with the plane of the wall it does not suffer the same impact from wind loading. The present teachings offer the facility of removing a central plate or pan, conducting inspections, affecting replacements or repairs and replacing the central plate or pan without disturbing abutting finishes.

Furthermore, the mechanism by which the proposed device operates is considerably simpler and more robust than anything revealed in the prior art.

Claim 1:
An expansion joint cover for insertion in an expansion gap comprising:
a first frame section (<NUM>) for attachment to a substrate at one side of the expansion gap, the first frame section having a flat surface (<NUM>);
a second frame section (<NUM>) for attachment to a substrate at an opposite side of the expansion gap, the second frame section (<NUM>) having a first set of connectors;
a centre section (<NUM>) configured to span the expansion gap and slide on the flat surface of the first frame section, the centre section having a second set of connectors; and
two linkage sections (<NUM>, <NUM>), configured to engage with the first and second sets of connectors, respectively, to connect the centre section (<NUM>) to the second frame section, wherein the linkage sections (<NUM>, <NUM>) can pivot with respect to the first and second sets of connectors to allow movement of the centre section (<NUM>) with respect to the second frame section (<NUM>) and to allow vertical movement of the centre section (<NUM>) with respect to the flat surface (<NUM>) of the first frame section while maintaining the centre section parallel with the flat surface (<NUM>) of the first frame section.