GB2464483A

GB2464483A - Facade system for buildings

Info

Publication number: GB2464483A
Application number: GB0818936A
Authority: GB
Inventors: Mikkel Kragh; Jan Wurm
Original assignee: Ove Arup and Partners International Ltd
Current assignee: Ove Arup and Partners International Ltd
Priority date: 2008-10-15
Filing date: 2008-10-15
Publication date: 2010-04-21
Also published as: WO2010043862A2; WO2010043862A3; GB0818936D0

Abstract

The invention relates to a facade system for multi-storey building and comprises structural elements mountable to a primary structure e.g. floor slabs of the building, wherein the structural elements provide thermal insulation. Each facade panel may comprise two vertical mullions 1 placed either side of a spandrel 2 and a window 3. The panels are preferably secured to the building frame by brackets at the back of the panels which take the horizontal and dead load of the panels. Extruded rubber gaskets (13 and 14 figure 2) may be used along the horizontal and vertical sides of the panel for weather and air tightness. The panels may be formed from fibre reinforced plastic (FRP) profiles made by pultrusion. Later embodiments relate to a panel for a facade system, and a method of assembling and manufacturing said facade system.

Description

FACADE SYSTEM FOR BUILDfNQ This invention relates to a facade system for multi-storey buildings, in particular to a curtain walling system.

Modem multi-storey buildings generally include a primary framework structure, of steel and/or concrete, with exterior walls of glass, metal, plastic, granite or the like, which form a facade for the building. The exterior walls, which will be selected for their appearance and for weather resistance, are generally made of panels formed into continuous areas extending about the building. This type of non-load bearing facade is commonly known as curtain walling. Known curtain walling systems use a secondary frameWork that is secured to the primary framework, with panels fixed to the secondary framework. The secondary framework can be an aluminium framework, used to support glass panels.

The need for a secondary framework in systems of this type is disadvantageous, as it results in added steps in assembling the facade system, and also generally requires additional space between the primary framework and the facade panels.

Viewed from a first aspect, the present invention provides a facade system for multi-storéy buildings comprising structural elements mountable to a primary structure of the building, wherein the structural elements provide thermal insulation.

In the prior art systems, the aluminium structural components conduct heat and do not provide any thermal insulation. Consequently, to provide the requisite thermal insulation the prior art facade systems must include thermal breaks as well as non-structural thermally insulating elements. The present inventors have identified that this results in a problem, as the facade systems become complex and bulky, and must extend outward from the building structure by some distance. By using thermally insulating material for the structural elements the structural enclosure is itself thermally insulating and hence the necessary structural strength and thermal insulation for the facade system are provided in a unitised manner. This enables a thinner facade system, with less components, as well as enabling the structural elements to act as part of the cladding for the building. Sucha system can be made to fit almost flush with the plane of the building frame, which provides better utilisation of the footprint of the building giving more floor space, and an improved appearance.

Preferably, the structural elements comprise a composite material, in particular a fibre reinforced polymer (FRP) material. FRP provides the required combination of structural strength and low thermal conductivity. In a preferred embodiment glass fibre reinforced polymers (GFRP) is used.

The preferred form of the structural elements is pultruded FRP elements.

Pultrusion is an effective way to produce FRP components, and pultruded elements with complex profiles can be formed in long lengths, and widths up to 1.2 m. Pultrusions can be formed in widths significantly larger than that available for aluminium extrusions, thus providing further advantages over known aluminium systems. Moreover, pultrusions can be cut to any desired length, giving great flexibility in the size and shape of the elements of the facade system. Preferably the profiles include hollows for air and/or additional thermal filler material.

In a preferred embodiment, the structural elements are joined to adjacent structural elements so as to transmit horizontal loads between the structural elements. The horizontal loads may be loads resulting from forces applied out of plane with the structural elements, for example loads arising from wind forces which deflect the structural elements out of plane. To enable loads to be transmitted, the structural elements may include interlocking elements for providing an interlocking joint to adjacent structural elements, preferably adjacent structural elements placed above and below. The interlocking elements may comprise a tongue and groove arrangement.

In a preferred embodiment at least some joints between side-by-side structural elements are arranged such that horizontal loads are not transmitted, i.e. these loads are transmitted only to structural elements above and below. Where the structural elements have vertical and horizontal edges, this means that the joints at the horizontal edges are preferably arranged to transmit loads that are out of plane with the structural elements, and the system preferably includes vertical joints that do not transmit such loads to adjacent elements.

Preferably, loads resulting from the dead load of the structural elements are not transmitted to adjacent structural elements, but instead brackets are provided for transmitting the dead load of the structural elements to the primary structure. The brackets may mount the structural elements coplanar with the exterior plane of the primary structure.

The structural elements may span vertically between horizontal elements of the primary structure, which may for example be floor slabs. Preferably the support elements are about the same length as the height between elements of the primary structure. This provides a convenient connection between floor slabs of a primary building structure and other elements of the facade system, and also enables the facade system to have repeating elements for each storey of the building.

The structural elements may join to adjacent structural elements above and below at the same level as the horizontal elements of the primary structure (i.e. at slab level), preferably however the joints are located part way between the horizontal elements, for example at cill-level. This joint location provides better accessibility to the joints during installation and also gives reduced bending moments within the structural elements due to the "Gerber-principle".

In a particularly preferred embodiment the structural elements comprise panels mountable to the primary structure. A facade system comprising panels can be assembled easily by simply mounting the panels to the exterior of the primary structure. The panels in the preferred embodiment are generally rectangular panels, arranged to be placed with sides of the rectangles oriented horizontally and vertically, but panels of different shapes and/or panels at an angle may be used.

Preferably the panels comprise mullions for providing the main structural strength of the panel. This enables the panels to include other non-structural elements, such as windows, shades, vents and so on. The mullions may be FRP pultrusions as discussed above. The mullions may be placed vertically, horizontally or at an angle. In a particularly preferred embodiment each panel comprises two vertically extending mullions either side of a non-structural element. Advantageously the two mullions can have an identical profile, being a mirror image of each other. This reduces the number of different profiles required.

The panel may include a spandrel section, for thermal insulation, and this is preferably mounted between two mullions, The spandrel may be an FRP pultrusion as discussed above. The arrangement of a spandrel and two mullions provides good structural properties across the width of the panel, and the mullions and spandrel may be fitted together form a U-shaped frame, which provides design flexibility and enables a window or the like to be easily incorporated into the panel. Preferably the mullions and spandrel are designed to fit together with a tongue and groove type interlocking arrangement. The panel may incorporate a window with a similar fitting to the mullions.

In an alternative arrangement, an 0-shaped frame may be used, comprising a complete panel with a hole punched out, such that the upright mullions and the spandrel may be integral parts of a single pultruded profile. The punched hole can be fitted with a window or the like.

Where the structural element comprises a panel with two mullions, the facade system preferably comprises two brackets for supporting the dead load of the panel, one on each mullion. This arrangement provides a stable support for the panel, with a simple bracket arrangement where each bracket supports mainly vertical load and horizontal loads out of plane with the panel. There is minimal twisting load, In an alternative arrangement, where a spandrel is present a single central bracket may be located on the back of the spandrel panel. This arrangement reduces installation time but will require additional engineering of the spandrel panel.

The facade system preferably comprises seals and/or gaskets for air and weather tightness. Gaskets may form part of the joints between adjacent structural elements. For example, a generally vertical gasket may be fitted between sides of adjacent elements or panels, and a generally horizontal gasket may be fitted between top and bottom of elements or panels above and below. In a preferred embodiment the gaskets allow for relative movement of adjacent panels and variations in the distance between panels when fitted whilst maintaining a weather tight seal. This avoids excessive loads being transmitted between adjacent structural elements as a result of relative movement, and thus reduces the load bearing requirements of any brackets joining the structural elements of the facade system to the primary structure of the building. It also means that the facade system has a good degree of dimensional tolerance in assembly. The horizontal gasket preferably fits to the tongue and groove arrangement that transmits horizontal out of plane loads. The tongue and/or groove hence forms a keyway to secure the gasket. Panel components can be joined and sealed by the use of adhesives or the like.

With the use of two separate mullions, the mullions may form uprights that are joined at the top and/or bottom by cross members in the form of a top closing piece and/or a bottom closing piece. This provides additional stiffness, and the top closing piece and/or a bottom closing piece can enclose a spandrel, a window or the like that is fitted between the mullions. The closing piece(s) preferably join to the mullion through a mechanical interlock. Where the mullion is a pultruded profile with parallel outer skins, the closing piece(s) are preferably fitted between the skins. This joint may be secured by a friction fit and/or adhesive. The mullion may include strengthening ribs, and in this case the ribs are machined out to enable fitment of the closing piece(s). Similar machining may be applied to ribs of a spandrel that is enclosed by the closing piece.

Preferably, one of the closing pieces forms a part of the frame of the window, and hence this closing piece may have a recess to accommodate a glazing unit that is between the mullions. With this arrangement the closing piece performs two functions, both providing a mounting point for the glazing unit and also providing stiffness by joining the two mullions. As the closing piece preferably has a continuous profile, an additional infihl section may be provided to fit into the recess and thereby ensure that the closing piece fits between skins of the mullion.

In a preferred embodiment the panel includes a top closing piece and a bottom closing piece, and the tongue and groove arrangement that transmits horizontal out of plane loads comprises a tongue in one of the closing pieces and a groove in the other closing piece. This arrangement enables the tongue and groove to be formed as features of a pultruded or extruded closing piece profile, and hence the closing pieces can be simply cut to length, with no machining or moulding required to produce the tongue and groove arrangement.

In a particularly preferred arrangement, the mullion and the top closing piece or bottom closing piece are joined by a corner moulding. With this arrangement the mullion and closing piece can be continuous profiles that are cut to length, with the complex geometry of the corner connection focused on a single small moulded element. By keeping the interface geometry constant the length and the width of the panel can vary without requiring additional moulds. This arrangement makes very effective use of the forms that can be achieved using continuous profile elements and the more complex forms that are possible with moulding, whilst avoiding the disadvantages of either process, as the moulded part is small, and the machining and fixings required to assemble the continuous profile parts is minimal.

This arrangement is considered to be inventive in its own right and therefore, viewed from a second aspect, the present invention provides a panel for a building facade system comprising: an extruded or pultruded mullion, an extruded or pultruded closing piece, and a moulded corner joint that forms a corner connection between the mullion and the closing piece.

Compared to prior art aluminium systems, a facade using this panel will have a reduced number of pieces. In addition, machining will be limited to straight cuts for adjusting length and to removing ribs (if necessary). Instead of labour intensive mechanical fixings, parts can be secured together by structural bonding andlor mechanically interlocking joints. These advantages are realised when conventional extruded components are used, but this system has particular utility with structural elements that provide thermal insulation, and thus in preferred embodiments the panel and mullions may have features as discussed above.

In particular the preferred material for the mullion and closing piece is pultruded FRP, and there may be two mullions, each mullion secured to a single closing piece by a respective corner moulding. FRP is particularly suited to structural bonding, and with the arrangement of at least the preferred embodiments the on-site process may be reduced to simply lifting panels into place, ensuring appropriate fltment of gaskets between adjacent panels, and securing the panels via brackets to the primary structure.

Preferably the corner moulding includes a first leg for engagement with a hollow in the profile of the mullion, and a second leg for engagement with a hollow in the profile of the closing piece. This simple mechanical connection provides a strong and rigid joint leading to a stiff panel. For a rectangular panel the first leg is vertical when fitted, and the second leg is horizontal, with a right angle between the two legs. In a preferred embodiment, one or both hollows have an irregular internal profile, with the corresponding leg having a corresponding external profile. The legs may fit in the corresponding hollows by a friction fit andlor with the use of adhesive.

The corner moulding may be arranged to fit flush with outer surfaces of the mullion and closing piece or, may be concealed within the mullion profiles. Preferably, the closing piece includes a tongue or groove for forming an interlock joint with an adjacent panel, and the corner moulding includes a corresponding tongue or groove element, such that the assembled closing piece and corner moulding provide a continuous tongue or groove. Advantageously, this continuous tongue or groove ensures continuity of a keyway for a gasket that connects to the closing piece as part of a joint between panels. In a preferred embodiment, a keyway for a gasket extends along the outside edge of the mullion, and the corner moulding has a corresponding keyway along at least a part of its first leg, such that this keyway and the keyway formed by the tongue or groove intersect. In this way a continuous keyway for a gasket for air and weather tightness can be formed about the change in direction of the surface in which the keyway is housed, i.e. extending around the corner joint in the panel.

Viewed from a third aspect, the present invention provides a method of assembling a facade system on a multi-storey building comprising: mounting structural elements to a primary structure of the building, wherein the structural elements provide thermal insulation.

In preferred embodiments, the structural elements have features as set out above and the method includes providing and assembling those features in accordance with the comments above.

The method may include mounting the structural elements in an array across the face of the building.

Viewed from a fourth aspect, the present invention provides a method of manufacturing a panel for a building facade system having an extruded or pultruded mullion, an extruded or puitnided closing piece, and a moulded corner joint, the method ôompnsing: cutting the mullion and closing piece to desired lengths, and using the moulded corner joint to connect the mullion and the closing piece about a corner of the panel.

In preferred embodiments, the structural elements have features as set out above and the method includes providing and assembling those features in accordance with the comments above. The method may include assembling a plurality of panels, and affixing the panels to a primary structure of a multi-storey building.

The invention also extends, in further aspects, to structural elements for use in or arranged to be used in the facade system of the first aspect. Such structural elements may include mullions, panels and the like, made of thermally insulating material, preferably pultruded FRP.

In all the aspects and embodiments discussed above the structural elements or panels may include materials selected for their acoustic properties. For example, layers of acoustically insulating material may be present. Where hollow extruded or preferably pultmded profiles are used then acoustically and/or thermally insulating materials may be provided within the hollows.

Certain preferred embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 shows a portion of a building facade consisting of four panels assembled together; Figure 2 is an exploded view showing the components of an embodiment of a building facade panel; Figure 3 shows the profile of the spandrel section of the panel; Figure 4 shows the profile of the mullions of the panel; Figure 5 shows the profile of the bottom closing piece of the panel; Figure 6 shows the profile of the window frame of the panel; Figure 7 shows the profile of the top closing piece of the panel; Figures 8A to 8D show the corner moulding that fits at the left hand of the panel asseeninFigure2; Figure 9 is a face on view of the four panels; Figure 10 is a close-up view of cross-section W-W in Figure 9, showing detail of the joint between the window and the spandrel; Figure 11 is a close-up view of cross-section W-W in Figure 9, showing detail of the interlock of the top closing piece and bottom closing piece at the horizontal joint between two panels; Figure 12 is a close-up view of cross-section X-X in Figure 9, showing detail of the interlock of the top closing piece and bottom closing piece at the horizontal joint between two panels; Figure 13 is a close-up view of cross-section Y-Y in Figure 9, showing detail of the joint between the mullion and the spandrel; Figure 14 is a close-up view of cross-section Z-Z in Figure 9, showing detail of a joint between the window and the mullion; and Figure 15 is a close-up view of cross-section X-X or Z-Z in Figure 9, showing detail of the vertical butt joint between two panels.

A part of a building facade system is shown in Figure 1, comprising four facade panels. Each panel consists of two vertical mullions 1, placed either side of a central spandrel 2 and window 3. The detail of the components securing these main parts of the panels together and details of the joints between panels is set out in more detail below.

The system shown is intended for use with a building frame comprising floor slabs extending outward from a central column support, but it will be appreciated that other building frame arrangements can be accommodated.

The panels are secured to the building frame (not shown) by brackets at the back of the panels, with each panel being the same height as the distance between elements of the building frame, which will typically be the height of a storey of the building. The brackets are for transfer of horizontal loads and the dead load (weight) of the panel. The bracket joins to the building frame and a part of the bracket is fixed to the panel by a metal counter-plate that is slotted along a vertical cavity of the mullion 1 and is fixed to the protruding part of the bracket by a pair of bolts. In this way the panel is mounted coplanar with the exterior of the building frame.

The panel is structurally connected along a horizontal "stack-joint" to the panels above and below for the transfer of horizontal loads between panels above and below each other, i.e. loads applied out of plane, such as loads arising from wind forces. Joints between the sides of adjacent panels take the form of "butt-joints", which transfer no forces but provide a continuous seal along the vertical panel edges.

In this preferred embodiment, brackets are placed on the mullions I at either side of each panel, at about the height of the lower edge of the spandrel 2, such that the stack joint between two panels is at a point midway up the height of the storey of the building.

By way of example, with this panel design a typical floor to floor height and panel height would be in the range 3600 to 4000 mm, with a panel width of about 1500 mm. The spandrel 2 and window 3 might have a width of about 900 mm with the spandrel height being around 1200 mm. In this case the stack joint would be around 900 mm away from the upper end of the support bracket. The depth of the panel would be about 105 mm in this embodiment.

In Figure 2, a single panel, and associated parts is shown in exploded view. The mullions I join directly to the spandrel 2 along the vertical sides of the spandrel 2 and interlock with the spandrel 2 to form a U-shaped frame. On the top and bottom edge a top closing piece 4 and bottom closing piece 5 are slotted into the open ends of the mullions 1 and the spandrel 2 to form the stack-joint interface. The bottom closing piece -10-.

also forms the bottom part of the window frame, which is completed by window frame elements 6 that are slotted into the mullions 1 and the spandrel 2 around the inside of the U-frame. The window 3 is formed by the window frame and by a glazing unit 23. An influl profile 7 is used to connect the bottom closing piece 5 to the mullions I on either side. An angle profile 8 mechanically fixes the bottom closing piece 5 to the mullion I at either side. Left and right corner mouldings 9 provide a mechanical interlock of the top closing piece 4 and the mullions 1. Between adjacent panels a horizontal gasket 13 and vertical gasket 14 are provided to ensure weather and air tightness, as well as being used to accommodate dimensional tolerances associates with the manufacture and assembly of the panels. The gaskets 13, 14 can be extruded rubber.

In general forces between the various components are transferred by contact and positive interlock connections. The components are fixed in position by mechanical fixings at strategic points andlor by the sealants or structural adhesives that fill the gaps between the profiles and provide the required weather and vapour tightness.

The connections between the various components will now be described in more detail with reference to the profiles of the pultrusions, which are shown in Figures 3 to 7, the corner moulding, shown in Figures 8A to 8D, and cross-sections showing detail of selected points, shown in Figures 10 to 15. The profiles of Figures 3 and 4 are shown at the same scale as each other, as are the profiles of Figures 5 to 7. The plate thickness of the profiles is 5 mm, except for the bottom closing piece 5 shown in Figure 5, which has a plate thickness of 6 mm to provide sufficient stiffness for the dead load of the glazing unit 23.

Figure 3 shows the profile of the spandrel 2. The C-profile of the mullion 1 along the interface to the spandrel 2 and window 3, as shown in Figure 4, allows the spandrel 2 to slot in as shown in Figure 13. This joint is fixed in position by a two component sealant (polyurethane or silicone) that fills the gap between the overlapping profiles. The same mullion profile can be used on either side of the spandrel 2, with left and right hand mullions I having identical profiles that are rotated by 180 degrees about a line normal to the plane of the panel. Left and right hand mullions I are placed symmetrically on either side of the spandrel 2 and window 3.

The vertical "posts" of the window frame profiles 6 are slotted into the C-profiles of the mullions 1, with the gap between the overlapping skins being filled with a single component polyurethane sealant. This joint is shown in cross-section in Figure 14. The window frame profile 6 is shown in Figure 6, and includes a recess ii that receives the glazing unit 23. An angled member 12 fits flush with the inner skin of the mullion I and covers the window frame profile 6.

The bottom closing piece 5 is shown in profile in Figure 5. The solid infill profile 7 is structurally bonded to the bottom closing piece by a two component polyurethane, a two component epoxy or an acrylate, and sits in the recess of the bottom closing piece 5 to extend across the width of the mullion 1. This can be best seen in Figure 12, which shows a cross-section of the horizontal joint between two panels, including the horizontal gasket 13. The ribs of the mullion I are machined out at the lower end to allow the bottom closing piece 5 and affixed infill profile 7 to slide in between the skins of the mullion 1. Figure 11 shows a cross-section of the horizontal joint between two panels similar to Figure 12, but cutting through the window 3 instead of the mullion 1, and hence illustrates the arrangement of the bottom closing piece 5 where it joins the glazing unit 23. In this case the recess 10 forms part of the window frame, as noted above. These components are fixed in position by a single component polyurethane along the edges of the closing piece 5 and infill profile 7. The bottom closing piece 5 is also mechanically fixed to the mullion by an angular profile 8 that is bolted to the bottom closing piece 5 and the rib of the mullion 1.

The connection of the horizontal window frame profile 6 and the spandrel 2 is shown in Figure 10, and resembles the connection between the spandrel 3 and the top closing piece 4. The elements slot into each other, and the gap between the overlapping skins is filled with a single component polyurethane. An angled member 12 fits flush with the inner skin of the spandrel 2 and covers the window frame profile 6. The horizontal and vertical angled members 12 and window frame profiles 6 have chamfered ends and form chamfered joints at the corners of the window 3.

The ribs of the mullion 1 and the spandrel 2 are machined out at their upper ends to allow the top closing piece 4 to slot in between the skins of the spandrel 2 and mullion 1. The top closing piece 4 is shown in profile in Figure 7. Figure 11 shows the spandrel 2 with the top closing piece 4, and Figure 12 shows the similar arrangement of mullion 1 and top closing piece 4. Again the components are fixed in position by the linear seal (a single component polyurethane) along both edges of the top closing piece 4.

The angular corner mouldings 9 are slotted into cavities of both the vertical mullions 1 and the horizontal top closing piece 4. The corner mouldings 9 are made in a left handed and right handed orientation, which are mirror images. The left handed corner moulding 9 (i.e. the moulding shown on the left in Figure 2) is shown in various views in Figures 8A to 8D.

As can be seen in these Figures, the corner moulding 9 includes a vertical leg 15 and a horizontal leg 16, extending at right angles to each other. The vertical leg 15 is sized to fit into a hollow 17 in the outer side of the profile of the mullion 1, as seen in Figure 4. The outer side of the mullion profile is the side that is at the outer edge of the panel after assembly. The horizontal leg 16 of the corner moulding 9 is sized to fit the hollow 18 in the profile of the top closing piece 4, as seen in Figure 7. These components are fixed in position by a linear seal around flanges 19 of the corner moulding 9, and by the mechanical interlock between the horizontal leg of the corner moulding 9 and the top closing piece 4 and the vertical leg of the corner moulding 9 and the mullion 1, which locks the structural frame of the panel together. The corner moulding 9, when assembled with the top closing piece 4 and mullions 1 sits between the outer skins of the mullions 1 where the ribs are machined out (as mentioned above).

The top closing piece 4 has two tongues 20 extending upward, and the left and right corner mouldings 9 also have corresponding pairs of tongues 21. When fitted in the mullions I and spandrel 2 the tongues 20, 21 are aligned and extend upward out of the top of the mullions I and spandrel 2. This can be seen in cross-section in Figures 11 and 12.

The bottom closing piece 5 has grooves 22 that receive the tongues 20, 21 when panels are joined top and bottom to form the stack joint between panels. The gap between the pairs of tongues forms a keyway for the horizontal gasket 13, and the alignment of the tongues of the corner mouldings 9 and the top closing piece 4 provides continuity of this keyway. The horizontal gasket 13 ensures that the desired mechanical interlock between the two panels is achieved, and hence completes the stack joint.

As noted above, the stack joint transmits horizontal loads between panels. The joint design allows for a relative vertical movement of 10 mm between panels, and to ensure that horizontal forces are transmitted a minimum of 6 mm of engagement of the tongue with the groove is maintained.

The butt joint is shown in cross-section in Figure 15. The vertical gasket 14 simply provides a seal between the mullions 1 of adjacent panels, and does not carry any significant load. The joint design allows for a horizontal in-plane movement of� 10 mm.

All of the profiles shown in Figures 3 to 7, as well as the infihl profile 7 and angled members 12 are formed as fibre reinforced plastic (FRP) pultrusions. Pultrusion is a process whereby fibres are pulled from a creel through a resin bath and then on through a heated die. Woven fibre fabrics may also be introduced into the die to provide fibre direction other than at 0°. The resultant profiles are similar to extruded profiles. The die completes the impregnation of the fibre, controls the resin content and cures the material into its final shape as it passes through the die. This cured profile is then cut to length.

The pultrusion process is a very fast, and therefore economic, way of impregnating and curing materials. The resin content can be accurately controlled and fibre cost is minimised since the majority is taken from a creel. The structural properties of laminates can be very good since the profiles have very straight fibres and high fibre volume fractions can be obtained. Hence, FRP pultrusions are well suited to the present application.

The matrix of the FRP material is a polymer. It is possible to use a variety of different types of polymer for the process. The most widely used polymer type is polyester, which is relatively low cost. Epoxy polymer can also be used -this material has superior mechanical properties but is significantly more costly than polyester and can be more difficult to process by pultrusion. Phenolic polymer has very good fire performance but lower strength and less durability. It is also possible to pultrude using acrylic polymer. This material is transparent, durable and can be highly filled with fire retardant.

Fibres can be used in the form of continuous, unidirectional groups (known as rovings), woven mat (e.g. bi-directional mat) or chopped strand mat (CSM). The unidirectional fibres provide the principal strength and stiffness along the axis of the pultrusion. The bi-directional mat provides off-axis properties. CSM can be used on the surface of the pultrusion to provide a resin-rich surface and mask the woven pattern of the underlying reinforcement.

There are three main fibre types that can be used practically in the pultrusion process, which are glass fibre, aramid fibre and carbon fibre. A suitable matrix and fibre combination can be selected according to the particular requirements of the facade system.

A preferred material is a GFRP pultrusion with the following composition (in accordance with EN 13706-1:2002 (E): -E-Glass fibre reinforcement, in accordance with ISO 3598 or ADVANTEX'.

-Surface veil.

-lsophthalic unsaturated polyester matrix resin.

-Fire retardant additive.

-Ultra-violet (UV) stabilising additive.

-Effective flexural modulus 23 GPa and other minimum values shown in EN13706-3:2002 (E) item 4.4.

Protective polyester surfacing veils are used and are selected to be compatible with the polyester resin matrix used in the FRP. The surfacing veils are used to produce a resin rich surface finish having fire retardancy.

The thermal conductivity of FRP material is low in comparison to metals, such as aluminium or steel. This low thermal conductivity is partly attributable to the low thermal conductivity of the matrix polymer. The fibre reinforcement also has a large influence, particularly since pultrusions have a high fibre volume fraction. Aramid fibre is the reinforcement with the lowest thermal conductivity -it is lower than common polyester matrix material. As FRP material has a lower thermal conductivity than aluminium extrusions the facade system described here provides substantial advantages over known facade systems that utilise aluminium extrusions as a frame for windows and the like. In addition, pultrusions can currently be produced up to a width of 1.2 m, which is significantly larger that the widths that can be achieved for aluminium extrusions.

The design of the various parts allows them to be simply cut to the required size from longer lengths of pultrusion. This provides a high degree of flexibility in the size and shape of the panels, and allows the same profiles to be used in various panel sizes arid shapes. For example, to produce a wider panel it is simply necessary to change the spandrel 2 and window 3 for widened components. The mullions 1 and corner mouldings 9 can remain the same and the top and bottom closing pieces 4, 5 and other horizontal profiles can simply be cut to a greater length.

The corner moulding 9 is a particularly important part in this context. By keeping the interface geometry constant the length and/or width of the panel can be varied without requiring additional moulds, and in many cases without needing to change all or even any of the pultruded profiles. The corner moulding 9 is manufactured by injection moulding with an appropriate polymer. Injection moulding is well suited to the shape required for the corner moulding 9.

The glazing unit 23 can be any suitable unit, which will be selected for the particular building that the facade system is for, with the size and structural abilities of the other panel components being adjusted as appropriate. This preferred embodiment is based on the use of a double glazed unit, which is assumed not to contribute to the overall stiffness of the panel. The exemplary double glazed unit used comprises 2 x 6 mm clear laminated safety glass on the inner face and a 10 mm monolithic glass on the outer face with a 14 mm cavity.

Assembly of the panel can proceed as below. Prior to assembly the various pultrusions are cut to size, the ribs of the mullions 1 are machined out at the upper and lower ends, and spandrel ribs are machined out at the upper end.

1. Angle profiles 8 are positioned and bolted to the bottom of the mullions 1, 2. Bracket counter-plates are inserted, positioned and clamped to mullions 1, 3. Vertical gaskets 14 fitted and cut to length for the butt joints between the mullions 1 (gaskets may be fitted on site) 4. Cavities of structural mullions I and spandrel 2 filled with rockwool-type insulation between ribs 5. Adhesive is applied to the inside of the C-profile of the mullions I where the spandrel 2 will be located, 6. Spandrel 2 is aligned with the top of the mullions 1 and pressed into the C-profile to form a U-shaped frame, 7. Lengths of window profiles 6 are measured and cut to length and seals are fitted 8. Bottom closing piece 5 is marked up and the infill profiles 7 are bonded to the bottom closing piece 5, 9. Window seal fitted to bottom closing piece 5, 10. Corner mouldings 9 are loosely fitted into both ends of top closing piece 4, 11. Top closing piece 4 and corner mouldings 9 are aligned and fitted into the top of the U-shaped mullionlspandrel frame, 12. Structural adhesive is injected along the parallel joints of the top closing piece 4 and the skins of the mullions I and spandrel 2, 13. Adhesive is injected at the joints of the top closing piece 4 and mullions 1 to structurally bond the corner moulds 9, and the corner mouldings 9 and top closing piece 4 are firmly fitted to the U-shaped mullionlspandrel frame, 14. The top window frame profile 6 is positioned in the bottom of the spandrel 2, and structural adhesive is injected along the parallel joints of the top window frame 6 and outer skins of the spandrel 2, 15. Adhesive is applied to the inside of the C-profiles of both mullions I where the vertical window frame profiles 6 will be located, 16. The left and right posts of the window frame 6 are aligned and fitted along the C-profile to match the chamfered corner connection of the horizontal window frame profile 6, 17. The bottom closing piece 5 with the bonded infill profiles 7 is aligned and inserted into the base of the mullions 1, 18. Adhesive is injected along the parallel joints of the bottom closing piece 5 and skins of the mullions 1, 19. Bolts are used to fix the bottom closing piece 5 to angle profile 8, 20. Structural silicone joint is applied to bond the glazing unit 23 to the window frame profiles 6 and bottom closing piece 5, 21., Structural silicone is applied along all weather joints, and 22. The horizontal gasket 13 is cut to size and fitted (this may be done on site).

The facade system can be provided with a protective or decorative coating on the interior andlor exterior surfaces, for example for colour or weather resistance.

Translucent GFRP components can be used, along with translucent insulation material in the cavities of the pultrusions the whole system in order to maintain a degree of translucency for the whole panel. This provides improved light levels, even where windows are not suitable or desirable, and produces an aesthetically pleasing finish of w type which is not possible with conventional aluminium systems. In addition the facade system may incorporate addonsu such as rain-screen or sunshade panels (glass, metal, FRC panels, etc) giving a maximum degree of design flexibility.

Only a single panel type is depicted in the preferred embodiment. However, various panel types can be made in accordance with the invention, and differing panel types can be used ma single facade. For example solid panels without windows can be used, or panels with varying heights of window and spandrel. It is also possible to have asymmetric mullions and/or panels with mullions of different widths, although it will be appreciated that this increases the number of components required.

In an alternative to the use of mirror image left and right corner mouldings 9, the corner pieces can be made with an identical shape if the profile of the top closing piece 4 is made with mirror symmetry about a vertical line, i.e. mirror symmetry about a vertical line with the profile oriented as in Figure 7. This means that only one mould is required.

However, the disadvantage of this approach is that the bottom closing piece 5 would need a similar degree of symmetry with regard to the interlocking tongue and groove arrangement, which places constraints on the shape of this part and has a knock on effect on the placement of the window frame recess 10. As a result, the use of symmetrical closing pieces is generally preferred only where there no window is required.

In a further alternative, corner mouldings 9 can be used at all four corners of a panel. These can be made as four separate mouldings, or by symmetrical design of profiles for the closing piece(s) 4, 5 and/or mullions 1, the number of mouldings required can be reduced to two (with one-fold mirror symmetry) or even to one (with two-fold mirror symmetry). This increases the advantages that are realised by restricting the complex geometry to a small number of moulded parts, but is of course offset by the additional constraints that arise in connection with the profiles of the pultruded components.

The preferred embodiment described above uses vertical mullions in a generally rectangular panel, However, the invention also extends to panels of different shapes and orientations, and mullions placed horizontally or at an angle. Many of the advantages provided by the present invention in relation to the ease of construction of panels, the combination of structural and thermal elements, and so on apply irrespective of the orientation of the panels. The use of angled panels and/or angled or horizontal mullions provides increased flexibility in the appearance and construction of the facade system.

Claims

CLAIMS: 1. A facade system for multi-storey buildings comprising structural elements mountable to a primary structure of the building, wherein the structural elements provide thermal insulation.
2. A facade system as claimed in claim 1, wherein the structural elements comprise a composite material, preferably a fibre reinforced polymer (FRP) material.
3. A facade system as claimed in claim I or 2 wherein the structural elements comprise pultruded profiles.
4. A facade system as claimed in claim 1, 2 or 3, wherein the structural elements are joined to adjacent structural elements so as to transmit horizontal loads between the structural elements.
5. A facade system as claimed in any preceding claim, wherein the structural elements include interlocking elements for providing an interlocking joint to adjacent structural elements
6. A facade system as claimed in any preceding claim, wherein the structural elements are arranged with interlocking elements such that horizontal loads are transmitted to adjacent structural elements placed above and below, and the joints between side-by-side structural elements are arranged such that horizontal loads are not transmitted..
7. A facade system as claimed in any preceding claim, wherein loads resulting from the dead load of the structural elements are not transmitted to adjacent structural elements, and brackets are provided for transmitting the dead load of the structural elements to the primary structure.
8. A facade system as claimed in any preceding claim, wherein the structural elements span vertically between horizontal elements of the primary structure.
9. A facade system as claimed in claim 8, wherein the structural elements join to adjacent elements above and below at a location part way between the horizontal elements.
10. A facade system as claimed in any preceding claim, wherein the structural elements comprise panels mountable to the primary structure.
11. A facade system as claimed in claim 10, wherein the panels comprise mullions for providing the main structural strength of the panel.
12. A facade system as claimed in claim 11, wherein the panel includes a spandrel section mounted between two mullions.
13. A facade system as claimed in claim 12, wherein the mullions and spandrel fit together with a mechanical interlocking arrangement.
14. A facade system as claimed in claim 12 or 13, comprising two brackets for supporting the dead load of the panel, one on each mullion.
15. A facade system as claimed in any of claims 11 to 14, comprising two vertically extending mullions that are joined at the top and/or bottom by one or more cross members in the form of a top closing piece andlor a bottom closing piece.
16. A facade system as claimed in claim 15, wherein the mullions comprise pultruded profiles with parallel outer skins and the closing piece(s) is/are fitted between the skins.
17. A facade system as claimed in claim 16, wherein the panel includes a top closing piece and a bottom closing piece, and comprise interlocking elements that transmit horizontal out of plane loads between adjacent panels above and below in the form of a tongue in one of the closing pieces and a groove in the other closing piece.
18. A facade system as claimed in claim 15, 16 or 17, wherein the mullion and the top closing piece or bottom closing piece are joined by a corner moulding.
19. A facade system as claimed in any preceding claim, comprising seals and/or gaskets for air and weather tightness, the gaskets forming part of the joints between adjacent structural elements.
20. A facade system as claimed in claim 19, wherein the gaskets allow for relative movement of adjacent panels and variations in the distance between panels when fitted whilst maintaining a weather tight seal.
21. A facade system as claimed in claim 19 or 20, wherein the structural elements include interlocking elements in the form of a tongue and groove arrangement for providing an interlocking joint to adjacent structural elements above and below and a horizontally extending gasket fits to the tongue and groove arrangement.
22. A panel for a building facade system comprising: an extruded or pultruded mullion, an extruded or pultruded closing piece, and a moulded corner joint that forms a corner connection between the mullion and the closing piece.
23. A panel as claimed in claim 22, comprising features as claimed in any of claims 11 to 21.
24. A panel as claimed in claim 22 or 23, wherein the mullion and the closing piece comprise pultruded FRP.
25. A facade system as claimed in claim 18 or a panel as claimed claim 22, 23 or 24, wherein the corner moulding includes a first leg for engagement with a hollow in the profile of the mullion, and a second leg for engagement with a hollow in the profile of the closing piece.
26. A facade system as claimed in claim 18 or a panel as claimed in claim 22, 23 or 24, wherein the closing piece includes a tongue or groove for forming an interlock joint with an adjacent panel, and the corner moulding includes a corresponding tongue or groove element, such that the assembled closing piece and corner moulding provide a continuous tongue or groove.
27. A method of assembling a facade system on a multi-storey building comprising: mounting structural elements to a primary structure of the building, wherein the structural elements provide thermal insulation.
28. A method as claimed in claim 27, wherein the structural elements are as claimed in any of claims 2 to 21.
29. A method of manufacturing a panel for a building facade system having an extruded or pultruded mullion, an extruded or pultruded closing piece, and a moulded corner joint, the method comprising: cutting the mullion and closing piece to desired lengths, and using the moulded corner joint to connect the mullion and the closing piece about a corner of the panel.
30. A method as claimed in claim 29, wherein the panel comprises a panel as claimed in any of claims 23 to 26.
31. A facade system for multi-storey buildings or panel for a building facade system substantially as described herein with reference to the accompanying drawings.31. A method of assembling a facade system on a multi-storey building or a method of manufacturing a panel for a building facade system substantially as described herein with reference to the accompanying drawings.