The present invention relates to a system for forming a curtain wall. In particular, the invention is concerned with a unitized steel curtain wall with expanded rubber joints.

Background

A conventional curtain wall comprises an aluminium grid incorporating panels that covers a building structure and hangs like a curtain. As such, a curtain wall is non- structural and can therefore be made of lightweight materials.

A stick system is usually employed for ground-floor curtain walls or for use in low- rise buildings. In the stick system, the curtain wall is installed as long pieces (referred to as sticks) between floors vertically and between vertical members horizontally. Framing members may be fabricated off site, but installation and glazing is typically performed at the jobsite .

Curtain walls can be made from units, which are fabricated elsewhere and then installed on the building structure . A unitized curtain wall has the advantages of speed of installation, lower field installation costs, and quality control within an interior climate-controlled environment.

Current unitized curtain wall systems rely on aluminum profiles having several cavities to accommodate non-compressible rubber gaskets and aluminium legs that interlock between panels. The current systems are designed in this way to allow thermal expansion and differential movement of the building structure supporting the panels. However, this results in complex and large cross sections of the profiles and in wide frames in comparison to stick system curtain walls.

Brief Summary of the Invention

According to a first aspect of the invention there is provided a system for forming a curtain wall, the system comprising two or more units,

each unit comprising a frame formed of frame members that houses an infill panel; the two or more units comprising a first unit that is joined to a second unit; wherein the first unit is joined to the second unit by a compressible joint.

The units may be joined horizontally, commonly known as “coupling” or joined vertically, commonly known as“stacking”.

According to a second aspect of the invention there is provided a method for fixing a curtain wall to a building structure, the method comprising

providing two or more units, each unit comprising a frame that houses an infill panel; fixing a first unit to a building structure; and

fixing a second unit to the building structure, the second unit being joined to the first unit to form a curtain wall;

wherein the first unit is joined to the second unit by a compressible joint.

The units can be fixed to the building structure in the conventional way to form the curtain wall, except that the units are linked by a compressible joint. Each unit (which comprises a frame housing the infill panel) is fixed to the building in turn.

According to a third aspect of the invention there is provided a building comprising the system of the first aspect.

According to a fourth aspect of the invention there is provided a kit for forming a curtain wall, the kit comprising

at least one infill panel;

a frame for housing the infill panel; and

a compressible joint.

The invention allows a wider selection of materials to be employed, rather than being limited to the aluminium frames of typical unitised curtain wall systems. Suitable materials for the invention are steel or materials with similar or higher strength and Young’s modulus properties as steel.

The frame may be a metal frame, such as a steel frame. Steel has higher mechanical strength than aluminium. However steel profiles have been excluded to date from unitized curtain wall systems due to the fact that steel profiles cannot be produced with the level of intricacy required in cross section geometry. In contrast, aluminum profiles can have deep cavities, grooves and ridges, all of which are required for curtain wall systems based on interlocking joints fitted with non-compressible gaskets. Hence the present invention provides a range of advantages, which are not possible for conventional unitized curtain wall systems.

Potential advantages are set out below.

The invention solves the problem of the need for large frame members of aluminum, and allows the use of smaller (e.g. steel) frame members.

The present invention allows a curtain wall system to be formed, which comprises modular units including a steel frame, an edge trim and an infill panel affixed to the frame, principally glass, with expanded rubber joints between the frames which prevents air and water from entering the building and provides thermal and acoustic insulation.

The invention allows the frame size to be reduced, as compared to the conventional curtain wall systems. As such, a more slender frame with a higher vision-area to frame-area ratio can be obtained.

The invention provides smaller spatial requirements for the joint between panels by using a compressible foam rubber gasket versus the non-compressible rubber sliding interlocking gasket used in conventional unitized curtain wall systems.

The invention allows the use of smaller horizontal load transferring members by using a compact pin versus the sword-type or sleeve-type coupling connectors used in conventional unitized curtain wall systems.

The invention allows a reduction in the depth of the overall curtain wall, compared to state of the art curtain wall systems, allowing for a smaller distance from the outer surface of the curtain wall to the structure of the building supporting it, and consequently allowing the building slab and flooring to extend closer to the external face of the wall and gaining usable floor area. The invention allows larger panel sizes to be achieved compared to current unitized curtain wall systems of an equivalent breadth and depth of framing members.

The invention may achieve lower deflections caused by wind pressure and suction compared to current curtain wall systems of an equivalent width and depth of framing.

The invention enables the frame to have surface finishes specific to steel, which are not possible on state of the art aluminium frame stick curtain wall systems.

The invention may enable the wall to constitute a fire-rated glazed partition with smaller spatial requirements than other existing fire-rated glazed partitions.

Frame

The frame houses the infill panel. The frame may comprise or consist of metal, such as titanium or steel (including mild steel or stainless steel) . Steel is an alloy of iron and carbon, and sometimes other elements. In one embodiment, the frame does not comprise aluminium.

The frame is formed from frame members, which may be generally vertical (a mullion profile / split mullion) or horizontal (a transom profile / split transom) in use, i.e. when attached to a building structure . The frame may be formed from three or more, four or more, five or more, six or more, or eight or more frame members and/or nine or fewer, seven or fewer, or five or fewer frame members. A typical frame may be rectangular and formed from two parallel mullion profiles and two parallel transom profiles, such that all internal angles are right angles (90°) . Such rectangular units can be installed in horizontal and vertical rows to form a flat vertical wall.

However, it is important to note that the system allows not only for rectangular units installed in horizontal and vertical rows to form a flat vertical wall, but also for trapezoidal, rhomboidal or other polygonal panels with straight or curved sides, and arranged in inclined, faceted or stepped manners to constitute multitude envelope geometries following the same process. In addition to quadrilateral panels, the system also allows panels with various numbers of sides, such as triangular or hexagonal panels.

The frame may be understood to have a mutually perpendicular height (H), width (W) and depth (D). The frame of the invention is believed to be more slender (have a smaller depth) than conventional aluminium frames. A schematic diagram of a front view of a rectangular frame is shown in figure 7.

The frame may have a depth of 200mm or less, 150mm or less, 120mm or less, 100mm or less, 90mm or less, 80mm or less or 70mm or less and/or the frame may have a depth of at least 30mm, at least 50mm, at least 70mm or least 80mm. The actual depth is mainly governed by acting wind pressure and span.

The frame may have a height / width of at least lm, at least 2m, at least 3m, at least 4m, at least 5m or at least 6m and/or the frame may have a height / width of 10m or less, 8m or less, 6m or less, 4m or less or 2m or less.

A frame member may be understood to have a mutually perpendicular length (L), breadth (B) and depth (D). A schematic diagram of a frame member (a transom profile) is shown in figure 7. It can be seen that the length (L) of the frame member corresponds to the width (W) of the frame. This is a schematic diagram; it will be understood that the frame members will have a suitable profile to receive a compressible joint in use (e.g. a U shaped profile).

A frame member may be understood to have a length measured along a longitudinal axis and a breadth and a depth measured in a plane perpendicular to the longitudinal axis, with the length being greater than the breadth and/or the depth. The length of a frame member will determine the height or width of a frame. The depth of the frame member is equivalent to the depth of the frame.

The system may comprise a plurality of frame members, wherein the plurality of frame members have (i) the same depth; (ii) the same breadth; and (iii) a variety of lengths. For example, a rectangular frame can be formed from four frame members, all of which have the same profile (breadth and depth) with two frame members having a first length and two frame members having a second length, that is different from the first length.

The frame members of the invention can be slimmer (have a smaller breadth and/or depth) than conventional aluminium frames.

Examples of suitable frame sizes (breadth (mm) x depth (mm) or vice versa) include 55x85, 60x90, 65x120 and 70x150.

A frame member may have a length of at least lm, at least 2m, at least 3m, at least 4m, at least 5m or at least 6m and/or a frame member may have a length of 10m or less, 8m or less, 6m or less, 4m or less or 2m or less.

A frame member may have a breadth of at least 10mm, at least 20mm or at least 30mm and/or a frame member may have a breadth of 100mm or less, 60mm or less, 40mm or 20mm or less.

Two frame members can be joined horizontally (e.g. coupled) to form a mullion or joined vertically (e.g. stacked) to form a transom. The total breadth of mullion/transom will include the sum of the breadth of each frame member and any space therebetween (filled by the compressible joint).

The frame members may be attached to one another by a mitre joint (mitre/miter corner). A mitre joint is made by beveling each of two parts to be joined, usually at a 45° angle, to form a corner, usually a 90° angle.

The frame members may comprise steel, which may be extruded, machined, rolled or drawn, for example to yield a specific profile. The frame members may be hollow or solid.

A frame member may be described with reference to its profile. The profile relates to a cross-section of the frame member in a plane perpendicular to the longitudinal axis.

The profile of the frame members may be selected in order to accommodate the compressible joint. At least one frame member may have a U-section (C-section) profile. Two adjacent frame members can define a cavity to accommodate the compressible joint. For example, two U-section frame members can define a cavity that accommodates a strip of compressible rubber.

At least one frame member may comprise a steel extrusion. The frame may be constituted by steel extruded profiles, which may be joined in mitred corners.

At least one frame member may comprise a steel machined profile. The frame may be constituted by steel machined profiles, which may be joined in mitred corners.

At least one frame member may comprise a steel rolled profile. The frame may be constituted by steel rolled profiles, which may be joined in mitred corners.

At least one frame member may comprise a steel drawn profile. The frame may comprise steel drawn profiles, which may be joined in mitred corners.

A bracket may be affixed to the frame serving to hang (connect) the unit onto a receiving bracket connected to the structure of the building.

Drainage channels may be formed into the cross sectional shape profile of at least one frame member and drainage holes can be cut into it.

A continuous horizontal rubber gutter gasket can be employed to collect and drive out at the stack joint any internal cavity condensation or external rainwater that may penetrate the first line of defense provided by external rubber gaskets and may drip down in front of the expanded rubber vertical strip.

A pin, such as a highly compact steel pin, can be fitted into the frame to allow the transfer of horizontal loads at the stack joint from a top panel to a bottom panel.

Compressible joint

The compressible joint is capable of expansion and contraction in use, i.e. reversible compression. The compressible joint comprises a compressible material, which will be compressed between units once installed on a building. The compressible joint may comprise expanded rubber, also known as foam rubber or sponge rubber. The compressible joint may comprise silicone foam/sponge, polyurethane foam/sponge, EPDM (ethylene propylene diene monomer) foam/sponge, PVC foam/sponge, neoprene foam/sponge, styrene-butadiene rubber (SBR) foam/sponge, nitrile rubber foam/sponge, natural rubber foam/sponge and d blends thereof.

The compressible joint may comprise a strip or strips of compressible material, such as a strip of expanded rubber. The strips of compressible material may be placed between the units to join (couple/stack) them together. The strips may be in direct contact with the frame itself, e.g. using structural adhesive to fix the strip to a frame member. Alternatively the strips may be in contact with an edge trim that is attached to the frame.

The compressible joint may be described with reference to its Movement Accommodation Factor (MAF), i.e. the movement the joint can accept in service expressed as a percentage of its original width.

Infill panel

The infill panels provide coverage to the building for both practical and decorative purposes. The infill panel may comprise glass, metal, ceramic, plastics, and combinations thereof including GFRC (glass fibre reinforced concrete) or GFRP (glass fibre reinforced polymer). Insulated glass units may be employed as the infill panels. The infill panels may comprise resin boards and/or reconstituted materials board.

The infill panel may be attached directly to the frame or via an edge trim, for example, by structural adhesive or exterior capping.

There is a risk that the force required to compress the compressible material (e.g. expanded rubber) inside the joints between the units might produce an undesirable in plane deflection or bowing to the frames in the axial direction of the compression force. This risk is greatest in a situation where the frame members are long. This in-plane deflection can be reduced. The system can employ infill panels that resist the compression force of the compressible material (e.g. expanded rubber) inflicted on opposite sides by the frame and/or edge trim to the infill panel and prevent the frame from bending. The invention also resides in the use of the infill panel to resist the deflection of the frame caused by the compression force, e.g. from the expanded rubber.

This can be achieved by the use of localized pads, packers or setting blocks located at required intervals on each side of the frame between the frame member and the infill panel or between the edge trim and the infill panel.

A setting block provides a cushion for an infill (e.g. glass) panel to sit on and support the panel deadload. In addition, the inventor proposes that a setting block can be employed to resist the compression force due to the use of a compressible joint.

Units

The system comprises a first unit that is joined (coupled / connected or stacked) to a second unit by a compressible joint. The units should be joined together to avoid leakage between the units.

The system comprises two (2) or more units, such as three (3) or more, five (5) or more, ten (10) or more, or twenty (20) or more units. The units may be joined together in series. For example, a third unit can be joined to the second unit on one side and to a fourth unit on another side.

The compressible joint may be employed to join frame members together, and thereby join the first unit to a second unit.

Alternatively, the first unit and second unit can be joined together without connecting the frame members directly. For example, the frame may additionally comprise an edge trim, and the compressible joint may be employed to join the first unit to the second unit via the edge trim. The unit may additionally comprise a load transfer pin.

The unit may additionally comprise an interlocking element to transfer horizontal loads at the stack joint from top panels to bottom panels and thereon to brackets and to the building’s structure.

The invention may be described with reference to the following clauses.

1. A unitized curtain wall system, comprising of:

a. A frame formed by steel mullions and transoms.

b. A set of expanded rubber strips affixed to said frame, and compressed in between panels (frames) once installed on the building. c. An interlocking element to transfer horizontal loads at the stack joint from top panels to bottom panels and thereon to brackets and to the building’s structure.

d. An infill panel affixed to said frame, principally glass or any other transparent, translucent or opaque material such as plastic sheet, metal sheet, porcelain tile, stone, GFRC or GFRP panels.

e. A bracket affixed to the said frame serving to hang (connect) the panel onto a receiving bracket connected to the structure of the building.

2. A unitized curtain wall system according to claim 1, where the frame profiles are steel extrusions joined in mitered welded corners.

3. A unitized curtain wall system according to clause 1, characterized by having drainage channels formed into the cross sectional shape profile and drainage holes cut into it.

4. A unitized curtain wall system according to clause 1, characterized by having a continuous horizontal rubber gutter gasket to collect and drive out at the stack joint any internal cavity condensation or external rainwater that may penetrate the first line of defense provided by external rubber gaskets and may drip down in front of the expanded rubber vertical strip.

5. A unitized curtain wall system according to clause 1, characterized by having a highly compact steel pin fitted into the frame of the lower panel that engages into a cavity extracted from in the frame of the upper panel allowing the transfer of horizontal loads at the stack joint from top panel to bottom panel. 6. A unitized curtain wall system according to clause 1 , characterized by having said infill panels assembled as a cassette comprised of a stepped insulated glass unit with the outer glass lite bonded with a structural adhesive to a carrier profile having also an outer rubber gasket, and an inner rubber gasket placed between the carrier profile and allowing the cassette to be mounted with mechanical fixings to the frame members.

Brief Description of the Drawings

Figure 1 is the horizontal section of the curtain wall mullions (vertical frame members) .

Figure 2 is the vertical section of the curtain wall stack joint transoms (horizontal frame members).

Figure 3 is a perspective view of the cruciform joint, representing the curtain wall installation sequence step A - installation of the first bottom panel, & step B - coupling of the second bottom panel.

Figure 4 is a perspective view of the cruciform joint, representing the curtain wall installation sequence step C - fitting of the horizontal expanded rubber strip, & step D - fitting of the rubber gutter gasket and load transfer pins.

Figure 5 is a perspective view of the cruciform joint, representing the curtain wall installation sequence step E - stacking of the first top panel, & step F - stacking and coupling of the second top panel.

Figure 6 demonstrates the use of structural adhesive (upper diagrams) and external capping (lower diagrams), with a thermal break (left side diagrams) and without a thermal break (right side diagrams).

Figure 7 is a schematic diagram showing a front view of two frames (upper image) and a perspective view of a single frame member.

Detailed Description of the Invention

In this detailed description, preferred embodiments of the inventive curtain wall system with steel frame and expanded rubber joints are described only for better understanding of the subject and in such a manner that it will not produce any limiting effect.

Steel frames ( 1) are assembled by joining mullion profiles ( 1. 1) and transom profiles ( 1.2) constituted by special U-section (sometimes known as C-section) steel profiles obtained by steel extrusion, milling, rolling, drawing or other methodology that allows to produce the required cross section.

To form the frame, the mullion profiles ( 1. 1) and the transom profiles ( 1.2), are cut to the correct length, preferably with mitred ends, and fixed together by welding at the corners and/or by another method of joining the corners that achieves the effect of forming stiff frames (1).

In those cases where mullion and transom profiles are hollow, a steel corner cleat (1.4) is to be fitted in the cavities at profile ends to stiffen the corner connection and to support the horizontal-load transferring pin (4) and the panel bracket ( 1 1). For solid profiles, the corner cleat may not be used.

After the frames are assembled, infill panels (7) are joined to the frames. The infill panels (7) can be assembled separately as a cassette and then connected to the frame with mechanical fixings (6) or, alternatively, the infill panels (7) can be directly bonded to the frame, or to an edge trim pre-fixed to the frame, with a structural adhesive or with external caps.

After the frames (1) are assembled, the edge trims (5) comprised of a profile (5.1), an internal gasket (5.2) and an external gasket (5.3) are connected to them with mechanical fixings (6). The edge trim profile may be aluminium or plastic for thermal break or a combination of both (crimped compound profile). Additionally, infill panels (7) are also fitted into the panels with structural adhesive (8) or with an external capping (9).

In addition to that, brackets (1 1) are connected to the frames ( 1) with bolts ( 10), in order to later allow the units to be fixed to the building structure.

Once the frame (1), edge trim (5) and infill panel (7) are joined, strips of expanded rubber, also referred to in the industry as foam rubber and sponge rubber (2), are attached to the panel edges in order to couple units horizontally to form a row of panels. The expanded rubber strips can be placed on all the sides of the panels before being lifted to be installed. However, the preferred methodology is to attach the vertical strip (2.1) individually to each frame prior to hoisting panels into their position on the building and to fit the horizontal strip (2.2) and the rubber gutter gasket (3) in a continuous manner on the horizontal joints over a series of panels already fixed to the building structure. The compressed rubber joints can be formed by a single strip on two sides of the four sides of the panel, so that strips compress against frame on adjacent panel (preferred method); or alternatively, strips can be fitted on all sides of the panel, where strips compress against similar strips on adjacent panels.

Before proceeding to stack the next row of panels on top of the existing one, the horizontal load transferring pins (4) are fitted in place. This will allow the wind loads and other horizontal loads to be transferred to the brackets and to the building’s structure. Another function of these pins (4) is to facilitate panel alignment and to help in the correct axis of compression of the gaskets.

After the pins are fixed on a row of panels, the panels for the row above are installed, by aligning the cavity in the frame of the top panel ( 1.3) with the position of the pin (4) in the bottom panel. A plastic cap (4.2) on the steel pin (4.1) is preferred to allow a smooth insertion and to prevent noises from panel movements during the life of the building at any given point in time.

It is important to note that as panels are installed, the expanded rubber strips (2) are to be compressed between the steel frame ( 1) in such a degree that they allow differential building movements and panel deflections from horizontal and vertical loads, resulting in widening and narrowing of joints, while always retaining enough compression to ensure air and water tightness of the system.

The process of coupling panels horizontally and stacking panels vertically is repeated over and over as needed to complete the wall. Finally, insulation, fire safing, and other internal finishes can be installed to close the gap between the back of the wall and the building structure.