RISER ASSEMBLY

Abstract

A riser assembly for construction of riser apertures in concrete floors comprises a frame member with a channel forming a shutter. A joist spanning the riser aperture is connected to the channel with a fixing which can slide axially within the channel when connected to the joist. A method of constructing the riser aperture is also disclosed, permitting the adjustment of the position of the joist by sliding the joist axially along the channel after the riser aperture is formed. Upper and lower walls of the channel converge to form a dovetail, which anchors the channel along its length within the settable material forming the floor around the riser, and also helps to retain the fixing within the channel.

Description

The present invention relates to a riser assembly for construction of riser apertures in concrete floors. In the modern construction of buildings, using concrete for the construction of floors in e.g. high-rise or multi-story buildings is convenient and efficient. Concrete is poured in situ to form floors and, using slip-forming techniques, can be used to form walls in situ also. The passage of service conduits for water, power, signals and waste etc. through multiple floors of high-rise buildings is usually accommodated by riser apertures passing through each floor at the desired location of the service pipes, permitting continuous passage of the service pipes through the riser aperture, and thus through the floor. Generally the position, size and shape of the riser aperture is considered when the building is designed, and can be cast in place when the floor is being constructed, using shuttering to define the boundary between the riser aperture and the surrounding floor. However, if service conduits need to pass through the floor which have not been accounted for in the design process, there can be considerable effort and lost site time as well as waste of materials in cutting, unbolting and re-fixing the service conduits and related support work in the riser aperture, often requiring hot works permits where metalwork is to be cut on site.

GB2265640, US2008/320365, GB2256211, and EP1860251 are useful for understanding the invention.

SUMMARY

The present invention provides a riser assembly for the construction of a riser aperture in a cast floor, the riser assembly comprising:

• • a frame member adapted to exclude settable material from the riser aperture, the frame member comprising a channel having an axis and a channel opening, the channel comprising an outer wall connected to upper and lower channel walls wherein the upper and lower channel walls extend between the outer wall and the channel opening;
  • a joist adapted to span at least a part of the riser aperture; and
  • a fixing adapted to connect the joist to the channel, wherein the fixing is adapted to slide axially within the channel when connected to the joist.

The invention also provides a method of constructing a riser aperture in a floor, the method comprising surrounding at least a part of the riser aperture with a frame member adapted to exclude settable material from the riser aperture, the frame member comprising a channel having an axis and a channel opening, the channel comprising an outer wall connected to upper and lower channel walls, wherein the upper and lower channel walls extend between the outer wall and the channel opening;

• • connecting a joist across at least a part of the riser aperture by connecting the joist into the channel opening by at least one fixing, wherein the fixing is slidable within the channel when connected to the joist; and adjusting the position of the joist by sliding the joist axially along the channel.

Typically the position of the fixing in the channel is locked by tightening the fixing (e.g. torqueing a threaded member in a nut) when the joist is in the desired location relative to the axis of the channel.

Optionally the channel has an inner wall which can be accessible from the riser aperture, and the upper and lower channel walls are connected between the inner wall and the outer wall, but in some examples, the inner wall can be optional.

Optionally the inner wall and outer wall are parallel, and in most cases will be horizontal in use. Optionally the inner wall is in a single plane. Optionally first (outer) ends of the upper and lower channel walls are connected to the outer wall, and second (inner) ends of the upper and lower walls are spaced from the outer wall and the first ends, and typically can be connected to the inner wall, or can themselves form the inner wall.

The outer wall, the upper and lower walls, and the inner wall can all be formed from a continuous sheet of material, e.g. a metal such as steel.

The channel opening can be provided between the second ends of the upper and lower channel walls, e.g. on the inner wall. The channel opening is thus accessible from the riser aperture. Optionally the outer wall of the channel is cast in the settable material forming the floor surrounding the riser.

The frame member typically also includes at least one shutter connected to the channel. Optionally upper and lower shutters are connected to the channel, optionally at the inner wall of the channel. Optionally the channel has lips extending between the upper and lower channel walls and the channel opening, and optionally the lips are aligned in a common plane at the inner wall of the channel, typically defining the channel opening between the lips. Each shutter is typically attached to a respective lip, typically each lip having a respective shutter. The shutters contain the settable material in the desired area, and define at their inner surfaces the inner wall to the riser aperture. Typically the shutters are generally L-shaped having a vertical component which is conveniently attached to the channel, and a horizontal component, which is typically set in or on the floor.

Optionally, the spacing between the first ends of the upper and lower channel walls at their connection to the outer wall is greater than the spacing between the second ends of the upper and lower walls that is further away from the outer wall, e.g. in line with the channel opening. Optionally the upper and lower walls at least partially converge as they extend from the outer wall, such that the convergent sections are non-parallel, and typically form a dovetail with the outer wall, typically along the length of the channel. This profile anchors the channel along its length within the settable material forming the floor around the riser, and also helps to retain the fixing within the channel.

Optionally the fixing is selectively lockable in the channel. In other words, the fixing can optionally be inserted into the channel in a first configuration, and while in the channel can then shift to a second configuration in which the fixing is locked in the channel. Optionally the fixing comprises an asymmetric (e.g. elongate) nut which can be rotated between the first and second configurations. Optionally the fixing has at least one outer wall arranged at the same angle as the inner surface of the upper and/or lower channel walls, such that the at least one outer wall of the fixing engages the inner surface (within the channel) of the upper (or lower) channel wall for example along its length when the fixing is locked in the channel in the second configuration.

Optionally the convergent sections of the upper and lower channel walls are straight. Optionally the angle between the outer wall and the upper channel wall is the same as the angle between the outer wall and the lower channel wall. For example, the angle between the outer wall and the upper and lower channel walls can be an acute angle, e.g. between 90° and 70°, e.g. 80°. This is one example, and different angles can be used with different examples. Optionally the upper and lower channel walls are set at different angles with respect to the outer wall of the channel, which in use is generally in a vertical orientation when cast into the settable material.

Optionally the frame member is rectilinear, and can be a quadrilateral, e.g. rectangular or square. The frame member typically defines at least one part of the boundary of the riser aperture, e.g. by excluding settable material such as concrete from the riser aperture and from the channel during casting of the floor surrounding the riser location. The joist typically spans between parallel sides of the riser aperture, each having a respective frame member. More than one joist can be provided. The joist is connected to the channel in at least one frame member by the fixing so that it is slidable relative to the channel at least at one end, but is typically connected between respective channels in frame members on opposite sides of the riser aperture, so that the joist is slidable at each end. Typically the opposite frame members are parallel.

Optionally a wall (e.g. an internal wall) can be constructed above the joist. Optionally the joist and the wall are at least partially in the same vertical plane and optionally the joist supports the wall.

Optionally the joist can be connected to the channel with more than one bracket at one end of the joist.

Optionally at least one frame member can be connected across the riser aperture by a fixing permitting sliding of the frame member relative to the channel when the two are connected, thereby dividing the initial riser aperture into sections, e.g. two sections, or more, and permitting a separate treatment of each section. In one example, first and second frame members can be connected across the riser aperture e.g. by a respective fixing on each frame member permitting sliding of the frame member relative to the channel when the two are connected. A settable material can then be cast into the space between the first and second frame members to form a beam that can support a wall, such as an internal wall. The relative positions of the first and second frame members can optionally be adjusting by sliding one of the first and second frame members axially along the channel to form a space between the first and second frame members.

The various aspects of the present invention can be practiced alone or in combination with one or more of the other aspects, as will be appreciated by those skilled in the relevant arts. The various aspects of the invention can optionally be provided in combination with one or more of the optional features of the other aspects of the invention. Also, optional features described in relation to one aspect can typically be combined alone or together with other features in different aspects of the invention. Any subject matter described in this specification can be combined with any other subject matter in the specification to form a novel combination.

Various aspects of the invention will now be described in detail with reference to the accompanying figures. Still other aspects, features, and advantages of the present invention are readily apparent from the entire description thereof, including the figures, which illustrates a number of exemplary aspects and implementations. The invention is also capable of other and different examples and aspects, and its several details can be modified in various respects, all without departing from the spirit and scope of the present invention. Accordingly, each example herein should be understood to have broad application, and is meant to illustrate one possible way of carrying out the invention, without intending to suggest that the scope of this disclosure, including the claims, is limited to that example. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. In particular, unless otherwise stated, dimensions and numerical values included herein are presented as examples illustrating one possible aspect of the claimed subject matter, without limiting the disclosure to the particular dimensions or values recited. All numerical values in this disclosure are understood as being modified by “about”. All singular forms of elements, or any other components described herein are understood to include plural forms thereof and vice versa.

Language such as “including”, “comprising”, “having”, “containing”, or “involving” and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term “comprising” is considered synonymous with the terms “including” or “containing” for applicable legal purposes. Thus, throughout the specification and claims unless the context requires otherwise, the word “comprise” or variations thereof such as “comprises” or “comprising” will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Any discussion of documents, acts, materials, devices, articles and the like is included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention.

In this disclosure, whenever a composition, an element or a group of elements is preceded with the transitional phrase “comprising”, it is understood that we also contemplate the same composition, element or group of elements with transitional phrases “consisting essentially of”, “consisting”, “selected from the group of consisting of”, “including”, or “is” preceding the recitation of the composition, element or group of elements and vice versa. In this disclosure, the words “typically” or “optionally” are to be understood as being intended to indicate optional or non-essential features of the invention which are present in certain examples but which can be omitted in others without departing from the scope of the invention.

References to directional and positional descriptions such as upper and lower and directions e.g. “up”, “down”, “upper”, “lower”, “vertical”, “horizontal” etc. are to be interpreted by a skilled reader in the context of the examples described to refer to the orientation of features shown in the drawings in normal use of the riser assembly, which is typically used with a floor that is poured and cast, and therefore level in a horizontal plane, and are not to be interpreted as limiting the invention to the literal interpretation of the term, but instead should be as understood by the skilled addressee.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 shows a riser in plan view using a riser assembly;

FIG. 2 shows a side view of one of the joists in the riser assembly of FIG. 1;

FIG. 3 shows a detailed view of a bracket connecting an end of the joist in FIG. 2 to a frame member of the riser assembly;

FIG. 4 shows a view from the inner wall of the frame member in FIG. 3;

FIG. 5 shows a perspective view of the end of the joist and the bracket in FIG. 3;

FIG. 6 shows a perspective exploded view of the end of the joist in FIG. 5;

FIG. 7 shows a plan view of a second riser using an alternative example of a riser assembly;

FIG. 8 shows a section view through A-A in FIG. 7;

FIG. 9 shows a section view through B-B in FIG. 7;

FIG. 10 shows a plan view of a third riser using another alternative example of a riser assembly;

FIG. 11 shows a series of views of the FIG. 10 riser and its components;

FIG. 12 shows a side view of a joist of the FIG. 10 riser;

FIG. 13 shows a perspective view of the channel of the FIG. 10 riser connecting to re-bars in a concrete wall;

FIG. 14 shows a perspective view of a bracket used with the riser assembly of FIG. 10;

FIG. 15 shows a perspective view of an inner wall of a wall using the riser assembly of FIG. 10;

FIG. 16 shows a side section view of the FIG. 15 wall during construction;

FIGS. 17 and 18 show perspective and side views of a fourth riser assembly; and

FIGS. 19 and 20 show perspective and side views of a fifth riser assembly.

DESCRIPTION

Referring now to the drawings, a riser aperture 1 provides a conduit extending vertically through a concrete floor 2. The riser aperture 1 is formed when the floor 2 is cast, by excluding the setting concrete from the area forming the riser aperture 1, using a riser assembly 5. The riser assembly 5 comprises a frame member 10 surrounding the riser aperture 1 The frame member 10 comprises upper and lower shutters 11, 12 connected to a channel 15 at an inner wall of the riser aperture 1.

The channel 15 (see FIG. 3) has upper and lower channel walls 15u, 15l extending toward the riser aperture 1 from an outer wall 150 which is embedded in the concrete of the floor 2 after casting. As shown in FIG. 3, in this example, the upper and lower walls 15u, 15l are non-parallel and extend from the outer wall 150 toward the inner wall of the riser aperture 1 at acute angles, which can be the same for each channel wall, but could also be different. In this case the angles made between the channel upper and lower walls 15u/15l and the outer wall 150 are between 90° and 70°. The non-parallel and convergent angles of the upper and lower walls 15u, 15l create with the outer wall a dovetail shaped cross section, which anchors the channel 15 securely in the floor 2 when the concrete is set, resisting lateral pull-out of the channel 15 from the floor 2, and reducing or avoiding the need for ties extending from the channel 15 back into the setting concrete to provide such anchoring.

The inner wall of the channel 15 has a channel opening 16 (see FIG. 6) extending along an axis 15x of the channel. The channel opening 16 is disposed between upper and lower lips 17 which extend from respective upper and lower walls 15u, 151, in a common horizontal plane forming the inner wall of the channel 15. The channel opening 16 faces and is in communication with the riser aperture 1, so that the channel opening 16 can be accessed from inside the riser aperture 1.

At the inner wall of the riser aperture, the upper and lower shutters 11, 12 take the form of L-shaped steel plates in this example and are connected to the channel 15, with the longer of the two limbs of each plate connected in a common vertical plane to the inner wall of the channel 15 and the shorter of the two limbs extending horizontally e.g. across the upper and lower surface of the floor 2, usefully containing the concrete while it is setting and excluding it from the riser aperture 1.

The channel 15 and the shutters 11, 12 can optionally be formed from metal, such as steel, and can optionally be welded (e.g. spot welded) together.

At least one joist 20 spans across at least a part of the riser aperture 1. In this example, each of the four joists in FIG. 1 extend between opposite parallel sections of frame member 10, but it is sufficient that at least one of the ends of the joists connects to at least one frame member via a bracket 25 connecting into the channel 15. The bracket 25 is best seen in FIGS. 4 & 5, having a generally L-shaped form and comprises a joist plate 25j connecting to the joist 20 by bolts, and a channel plate 25c at right angles to the joist plate 25j with a tab 25t which engages in the channel opening 16 as shown in FIG. 5, to resist rotation of the bracket 25 when the bracket 25 is fixed onto the channel 15.

A bolt 27b passes through the channel plate 25c and the channel opening 16, and engages an asymmetric channel nut 27n which is disposed inside the channel opening 16 and is optionally urged against the inner surface of the channel opening 16 by a spring 27s held in compression between the nut 27n and the inner surface of the outer wall 150. The nut 27n has a long axis, and can be received in the channel opening when the long axis of the nut 27n is aligned with the axis of the channel 15, but is retained in the channel when the long axis of the nut 27n is not aligned with the axis of the channel opening 16, and so the nut 27n can be selectively locked in the channel 15 depending on the relative orientation of the nut 27n and the channel opening 16. The nut 27n and bolt 27b together provide a fixing 27 cooperating with the bracket 25 that connects the joist to the channel 15 through the channel opening 16 so that the joist 20 is slidable. When the nut is tightened on the bolt and the bracket is fixed in position, the joist 20 is fixed relative to the channel, but when the nut 27n is loosened slightly on the bolt 27b, the fixing 27 permits sliding movement of the bracket 25 and joist 20 along the axis of the channel 15 while still connected to the channel, thereby permitting sliding adjustment of the horizontal position of the joist 20 relative to the channel 15 when the two are loosely attached by the fixing 27. Once the joist 20 is in the desired position along the axis of the channel 15, the nut 27n and its bolt 27b can be tightened again to fix the joist 20 in position. The nut 27n has at least one section of outer wall that is shaped to be complementary to the inner surface of at least one of the upper and lower walls of the channel. For example, where the upper and lower walls of the channel converge at, say, 80°, a section of outer wall of the nut 27n can be formed at the same angle, so that as the nut 27n rotates into contact with the inner surface of the upper or lower wall of the channel, the outer wall of the nut 27n and inner surface of the channel are contiguous along at least a part (and optionally the whole) of the length of the outer wall of the nut 27n, which can help to lock the nut 27n more securely in position. When the joist 20 is fixed onto the channel 15 by the fixing 27, rotation of the joist 20 is resisted by the tab 25t which extends into the channel opening 16.

The joists 20 support a floor formed by a grating 30. The grating 30 and joists 20 and optionally other structural members such as beams extending across the riser aperture (e.g. between the frame members 10) can optionally be formed from a composite material such as a fibre-reinforced material like GRP, which can be formed by extrusion or pultrusion and can be easily drilled and/or cut to size, and bolted in place.

Should the desired route of a particular service conduit through the riser aperture 1 coincide with the existing position of a joist 20, that joist 20 can simply be loosened (optionally from above the riser aperture 1) by raising a floor panel of grating 30, loosening the fixing 27, and sliding the joist 20 laterally to a new position within the riser aperture 1, out of the path of the service conduit, after which the joist 20 can then be fixed in position again by tensioning the fixing 27. Minor deviations of the joists away from regularly spaced intervals between the frame members 10 need not affect the overall structural integrity of the riser assembly because the joists 20 can be engineered to take the load within tolerance even if they are not spaced at regular intervals, and if desired, for heavier loads, additional joists 20 can be added on each side of the service conduit after it passes through the riser aperture 1 if additional reinforcement of the floor grating 30 is required. This can be accomplished from above the riser assembly 5 simply by lifting a panel of grating 30.

FIGS. 7-9 show a second example of a riser assembly 105, similar to the riser assembly 5, having frame members 110a,b similar to frame members 10 arranged in a rectilinear frame having two long frame members 110a and two short frame members 110b, with the same design of channel 115 as channel 15, and joists 120 similar to joists 20, and with the same design of bracket 125 as bracket 25, and the same grating 30 as described above. The same description of similar elements will not be repeated for brevity, and the reader is referred to the description above for riser assembly 5 for the details. In the riser assembly 105 there are two different types of joist: at least one short joist 120a, and at least one long joist 120b. Instead of the joists connecting at each end to the frame members and spanning the entire breadth of the riser aperture 1 as described above for the riser assembly 5, a bracket 125 is connected to only one end of each of the short joists 120a, which are slidably connected to only one frame member 110a as previously described. The opposite ends of the short joists 120a are each connected to the long joist 120b, which is connected across the length of the riser aperture 101 between the shorter side frame members 110b, either by use of the slidable connection with the bracket, fixings and channel as described for the riser assembly 5, or with simple L-shaped brackets that are bolted at each limb between the joist 120b and the side frame members 110b. The connection between the short joists 120a and the long joist 120b can similarly be by a slidable connection with the bracket, fixings and channel as described for the riser assembly 5, or with simple L-shaped brackets that are bolted at each limb between the joists 120a and the joist 120b. In this example, the joist 120b divides the riser aperture 1 into two unequal areas, and can optionally be slid (if connected by bracket 125 and channel 115 into the frame members 110b) as previously described for the joists 20 to adjust the relative sizes of the two areas, or otherwise fixed in the desired position, to create a longer end aperture for wider service conduits to pass unobstructed. The smaller joists 120a extending between the frame member 110a and the joists can be initially connected by the brackets 125 to the frame member 110a, and slid along the axis of the frame member 110a to the desired position before being fixed in place as described. Then the other end of each short joist 120a is fixed to the long joist 120b, either by bolting into the long joist 120b, or by the sliding connection using the bracket 125 and channel 115 as described above. This permits adjustment of the relative positions of the joists 120a. 120b to accommodate service conduits as they are offered to the riser aperture as described above.

FIGS. 10-16 show a third example of a riser assembly 205 similar to the riser assembly 105 described above with reference to FIGS. 7-9, having frame members 210a, 210b and joists 220a, 220b similar to those described in the second example, but having a different frame member 210c on a side wall attached to a slip-formed wall W. The riser assembly 205 is intended for use in a location where the riser aperture is positioned against the slip-formed wall W, which forms a part of its boundary. The wall W incorporates re-bars R fixed in place to form a skeleton structure before casting (see FIG. 13), and the frame member 210c is fixed in position by ties connecting it to the re-bars R. As best seen in FIG. 13, the frame member 210c has a channel 215, similar to those described previously, and upper and lower shutters 211, 212 [, similar to those described previously, except that the shutters 211 and 212 incorporate in their upper and lower horizontal walls an array of perforations P, which are adapted to admit concrete into the spaces between the channel 215 and the shutters 211, 212 when the concrete is poured. The vertical walls of the shutters 211, 212 are welded to the channel 215 thereby containing concrete in that area, and excluding it from the riser aperture 201. During construction of the wall W, the skeleton of re-bars R is tied together e.g. with wire ties as shown in FIG. 13, the frame member 210c is similarly tied to the re-bar skeleton in the desired location, and the wall is slip-formed, as generally shown in FIG. 16, by casting sequential sections onto the re-bar skeleton as the shutters on the slip-forming shutters move in gradual steps up the skeleton. When the slip-form shutters reach the channel 215, the concrete pours through the perforations P occupying the space around the channel 215, but being excluded from the riser aperture 201 by the vertical walls of the shutters 211, 212, thereby anchoring the channel and shutters 211, 212 into the wall W as it is formed. The floor 202 is optionally cast in the same step, with the frame member 210c at the interface between the wall W and the riser aperture 201. The end result as shown on the right hand side in FIG. 11 is that the floor 202 is formed with the riser aperture 201 at its lateral edge adjacent to the wall W. The riser assembly 205 can have all of the features of the previous examples 5 and 105.

As previously described, the joists 20a, 20b are connected to the frame members 210a, 210b, 210c, by at least one slidable fixing, permitting sliding movement of the joists 220220a, 220b within the riser aperture 201. This permits adjustment of the relative positions of the joists 220a, 220b to accommodate service conduits as they are offered to the riser aperture 201, as described above.

An optional service fixing bracket 28 can be connected into the channel 215 to permit the attachment and support of any particularly heavy service conduits. This is especially useful when the bracket 28 is hung on the frame member 210c connected to the wall W, since the weight of the heavy service conduit can be supported by the wall W. However, the bracket 28 can optionally be used on other frame members 10 or 10a at different sides of the riser aperture 1, 101, 201 etc.

FIGS. 17-18 show a fourth example of a riser assembly 305, similar to the riser assembly 5, having frame members 310 similar to frame members 10, with the same design of channel 315 as channel 15, and joists 320 similar to joists 20, and with the same design of bracket 325 and the same grating 30 as described above for the first example. The same description of similar elements will not be repeated for brevity, and the reader is referred to the description above for riser assembly 5 for other common details.

In the riser assembly 315 spacing first and second channels 315 apart from one another in the same plane and (in this example) in parallel relationship enables the formation of a rectangular beam between them from settable material such as concrete, which can be poured into a shuttered area formed between the two channels 315 and cast in place, thereby spanning across the riser aperture to divide it. In the FIG. 17-18 example, frame members 310 comprising channels 315 and upper and lower shuttering plates 311, 312 similar to the plates 11, 12 previously described are arranged on either side of the shuttered area and maintained in position (e.g. by the shuttering). The side-by-side frame members 310 are connected across the shuttered area by carrier plates 312 forming a brace, and which receive re-bars extending along the length of the shuttered area, being embedded in the beam once cast in the shuttered area. The re-bars are held in the desired configuration, reinforcing the beam once the concrete is poured. The beam can be used as the foundation for the construction of a wall if desired, across the top of the riser aperture, allowing additional flexibility for adjustment of the internal arrangement of the building after the initial construction of the floor and determination of the location and size of the riser aperture.

FIGS. 19-20 show a fifth example of a riser assembly 405, similar to the riser assembly 5, having frame members 410 similar to frame members 10, with the same design of channel 415 as channel 15, and joists 420 similar to joists 20, and with the same design of bracket 425 as bracket 25, and the same grating 30 as described above. The same description of similar elements will not be repeated for brevity, and the reader is referred to the description above for riser assembly 5 for common details.

In the riser assembly 405, a beam B with a conventional I-shaped cross section supported on either end by brackets 425 connected into a frame member 410 having a channel 415 and upper and lower shuttering plates 411, 412 as previously described, so that the beam B is slidable parallel to the axis of the channel 415. The beam B provides a support for a wall W, permitting the wall to span across the riser opening 401. This variation uses the considerable strength of the channel 415 as a fixing method and means that a long riser can be installed spanning over a number of different horizontal partitions of the building, and one or more dividing walls between the rooms can be formed over the riser aperture as the project progresses, i.e. after the riser opening has been formed and the floors surrounding it poured, and even allows the location of the beam B to be adjusted once in situ. This is especially useful if the precise position of the internal walls was uncertain at the time of initial design and/or casting in of the riser assembly 405, since the position of the wall W relative to the riser opening can be varied relatively easily by sliding the bean B into the desired position along the channel 415 and tightening the fixings connecting the brackets 425 into the channel 415 before construction of the wall W.

Claims

1. A riser assembly for the construction of a riser aperture in a cast floor, the riser assembly comprising: a frame member adapted to exclude settable material from the riser aperture, the frame member comprising a channel having an axis and a channel opening, the channel comprising an outer wall connected to upper and lower channel walls wherein the upper and lower channel walls extend between the outer wall and the channel opening;a joist adapted to span at least a part of the riser aperture; anda fixing adapted to connect the joist to the channel, wherein the fixing is adapted to slide axially within the channel when connected to the joist.

2. A riser assembly as claimed in claim 1, wherein first outer ends of the upper and lower channel walls are connected to the outer wall, and second inner ends of the upper and lower walls are spaced from the outer wall and the first ends, and wherein the spacing between the first ends of the upper and lower channel walls is greater than the spacing between the second ends of the upper and lower walls.

3. A riser assembly as claimed in claim 1, wherein the upper and lower walls at least partially converge as they extend from the outer wall forming non-parallel convergent sections of the upper and lower channel walls.

4. A riser assembly as claimed in claim 1, wherein the cross-section of the upper and lower walls and the outer wall has the form of a dovetail along the length of the channel.

5. A riser assembly as claimed in claim 1, wherein the frame member includes upper and lower shutters connected to the channel, wherein the upper and lower shutters are in a common plane with the channel opening.

6. A riser assembly as claimed in claim 1, wherein the channel has lips extending between the upper and lower channel walls and the channel opening, and wherein the lips are in a common plane with the channel opening.

7. A riser assembly as claimed in claim 1, wherein the fixing is selectively lockable in the channel.

8. A riser assembly as claimed in claim 7 wherein the fixing can be inserted into the channel in a first configuration, and while in the channel can then shift to a second configuration in which the fixing is locked in the channel.

9. A riser assembly as claimed in claim 8, wherein the fixing comprises an asymmetric locking member which can be rotated between the first and second configurations.

10. A riser assembly as claimed in claim 7, wherein the fixing comprises at least one outer wall arranged at the same angle as an inner surface of at least one of the upper and lower channel walls, such that the at least one outer wall of the fixing engages the inner surface of the at least one of the upper and lower channel walls when the fixing is locked in the channel in the second configuration.

11. A riser assembly as claimed in claim 1, wherein convergent sections of the upper and lower channel walls are straight.

12. A riser assembly as claimed in claim 1, wherein the upper and lower channel walls make an acute angle with the outer wall of the channel.

13. A riser assembly as claimed in claim 1, wherein the angle between the outer wall and the upper channel wall is the same as the angle between the outer wall and the lower channel wall.

14. A riser assembly as claimed in claim 1, wherein the joist spans between parallel sides of the riser aperture, and wherein at least one end of the joist is connected to the channel in at least one frame member by the fixing so that it is slidable relative to the channel at least at one end of the joist.

15. A riser assembly as claimed in claim 1, having at least first and second joists, wherein one end of the first joist is connected to the frame member and the other end of the first joist is connected to the second joist.

16. A riser assembly as claimed in claim 1, wherein the joist is formed from a composite material comprising a fibre and a settable material.

17. A riser assembly as claimed in claim 1, wherein at least one frame member is incorporated in a slip-formed wall which forms a part of the boundary of the riser aperture.

18. A riser assembly as claimed in claim 17, including a bracket supporting a service conduit passing through the riser aperture wherein the bracket connects into the channel of the frame member supported on the slip-formed wall.

19. A method of constructing a riser aperture in a floor, the method comprising surrounding at least a part of the riser aperture with a frame member adapted to exclude settable material from the riser aperture, the frame member comprising a channel having an axis and a channel opening, the channel comprising an outer wall connected to upper and lower channel walls, wherein the upper and lower channel walls extend between the outer wall and the channel opening; connecting a joist across the riser aperture by connecting the joist into the channel opening by at least one fixing, wherein the fixing is slidable within the channel when connected to the joist; andadjusting the position of the joist by sliding the joist axially along the channel.

20. A method as claimed in claim 19, wherein after the step of adjusting the position of the joist by sliding the joist axially along the channel, the position of the fixing in the channel is locked by tightening the fixing when the joist is in the desired location relative to the axis of the channel.

21. A method as claimed in claim 19, wherein the channel opening is accessible from the riser aperture, and wherein the outer wall of the channel is cast in the settable material forming the floor surrounding the riser aperture.

22. A method as claimed in claim 19, wherein at least one frame member is formed in a slip-formed wall, which forms a part of the boundary of the riser aperture.

23. A method as claimed in claim 19, wherein the at least one frame member is fixed in position on the slip-formed wall by ties connecting it to metal reinforcing elements prior to slip forming the slip-formed wall.

24. A method as claimed in claim 19, wherein the riser assembly comprises upper and lower shutters connected to the channel, wherein the upper and lower shutters incorporate upper and lower horizontal walls each having an array of perforations, and wherein the method includes admitting concrete into the spaces between the channel and the upper and lower shutters.

25. A method as claimed in claim 19, including supporting a service conduit passing through the riser aperture with a bracket which connects into the channel and is slidable therein.

26. A method as claimed in claim 19, including constructing a wall above the joist, wherein the joist and the wall are at least partially in the same vertical plane and wherein the joist supports the wall.

27. A method as claimed in claim 19, including connecting the joist to the channel with more than one bracket at one end of the joist.

28. A method as claimed in claim 19, including connecting at least one frame member across the riser aperture by a fixing permitting sliding of the frame member relative to the channel when the two are connected.

29. A method as claimed in claim 28, including connecting first and second frame members across the riser aperture by a respective fixing on each frame member permitting sliding of the frame member relative to the channel when the two are connected; adjusting the relative positions of the first and second frame members by sliding one of the first and second frame members axially along the channel to form a space between the first and second frame members; andcasting a settable material into the space between the first and second frame members.