GB2407329A - Building structure with a tensile membrane - Google Patents

Abstract

A building is constructed using parabolic arches. A tensile membrane is placed over the arches such that the membrane is in contact with the arches over a central region but extends away from the arches over a peripheral region. The membrane is secured in tension at its edges so as to define an anticlastic surface. A wall is built to present an upper wall surface above ground level and edges of the membrane are secured to the upper wall surface. A central floor area under the central region of the structure is excavated below ground level. A structure provides a large covered space for use as an arena or similar application while construction costs are substantially reduced compared to known configurations for facilitating similar applications.

Description

Building Structure with a Tensile Membrane

Background of the Invention

The present invention relates to building structures with tensile membranes and in particular to large closed building structures that may be used for performance activities such as sporting and religious activities etc. Preferably, the present invention provides a building structure with a tensile membrane for use as a permanent arena.

A problem with large structures of this type is that the cost of 0 construction can be considerable in order to achieve appropriate dimensions.

Brief Description of the Several Views of the Drawings Figure 1 shows an excavation process forming part of a preferred embodiment; Figure 2 shows the provision of a concrete foundation; Figure 3 shows the provision of inclined seating in a preferred embodiment; Figure 4 shows the provision of parabolic arches; Figure 5 shows the provision of stabilising cables; Figure 6 shows the provision of sky boxes; Figure 7 shows the fabrication of fabric membrane panels; Figure 8 shows a fully assembled structure; Figure 9 shows a cross sectional view of the fully assembled structure shown in Figure 8; and Figure 10 shows an end view of the fully assembled structure shown in Figure 8. l

Written Description of the Best Mode for Carrying Out the Invention Figure 1 For the purposes of illustration, an erection process will be described for an embodiment of the invention. However, it should be appreciated that many other techniques may be used in order to achieve the construction of a building structure in accordance with the invention.

In a first preferred erection process, in order to optimise the space provided within the structure of the preferred embodiment, excavation is performed as illustrated in Figure 1 such that a central floor area (configured for the performance of a viewed activity) and part of an inclined seating area, provided around said central floor area for viewers of said viewed activity, are below ground level. Thus, a substantially trapezoid excavation 101 is created having a flat central floor area 102 and four inclined planes 103, 104, 105 and 106.

In an alternative embodiment, possibly for alternative uses such as exhibitions etc. different types of excavations may be performed such that walls 102 to 106 could be substantially vertical. Alternatively, an embodiment of the invention could be deployed without performing initial excavation work.

Figure 2 After the excavation work has been completed, creating excavation 101, a concrete foundation 201 is laid around the excavation so as to define a parameter. A foundation ring beam is laid substantially below surface level to an extent that will depend upon ground conditions. Furthermore, at this stage, further excavation work is performed in order to provide for the drainage of rainwater and the drainage of waste material generated within the structure itself.

An advantage of performing excavation work, before building the structure itself, is that it becomes possible to reduce the overall height of the structure while achieving appropriate space and volume within the structure itself. It should be appreciated that the building of vertical walls and similar structures becomes considerably expensive given that the forces applied to these structures can become extremely large. For example, as the wall height increases leverage at the base becomes considerable. Thus, overall costs may be reduced significantly if the height of external walls may be reduced.

Figure 3 In a preferred embodiment, a central floor area is configured for the performance of a viewed activity, such as baseball, football, icehockey or similar sporting activities. The central floor area is therefore surrounded by inclined seating for viewers of the viewed activity. Furthermore, a preferred embodiment also includes private boxes, generally referred to as sky boxes given that they tend to be provided at positions above the general seating plan.

A typical conventional arena configured to provide seating for fifteen thousand spectators generally requires external walls of a height of fifteen metros or higher. Constructions of this type add significantly to the cost of the building. A preferred embodiment of the present invention reduces these costs significantly by providing walls in the region of typically eight to twelve metros. For example, in a specific embodiment an external wall 301 is built to a height of nine metros.

In its configuration as an arena, substantial support is given to the external wall 301 by the provision of seating 302. However, in situations where seating 302 does not provide sufficient support for wall 301 additional buttresses 303 are provided external to the wall 301.

In a preferred embodiment, seating terraces 302 are cast in-situ.

Similarly, part of this casting operation also provides for the inclusion of underground concourses and general entry and exit locations. Locations under seats also provide space for storage and office locations etc along with sales outlets and public conveniences.

0 Figured A roof for the structure is supported by parabolic arches, four of which are shown in the present embodiment, referenced 401, 402, 403 and 404.

However, it should be appreciated that the intrinsic nature of the preferred design is such that the number of arches may be extended indefinitely such that the choice of design will be selected based upon its intended applications. Thus, in alternative applications the number of parabolic arches could be extended to six, eight or ten etc. The inherent structural integrity of the parabolic arch is such that the arches could be manufactured from many types of structural materials. For example, the arches could be constructed from welded sections of steel, prefabricated glass fibre or pre-cast concrete sections. At ground level, the arches are secured within adjustable column bases. The arches are introduced for assembly at ground level and then rotated into position and thereafter temporarily held in position by the provision of stabilising cables. In the preferred embodiment, the arches extend through the seat terracing 302 at interfaces 405, that are above ground level.

It is appreciated that the introduction of the arches at these interface positions does result in a number of blind spots lying behind the arches themselves. However, much larger regions exist, such as region 406, at positions between the arches such that the amount of lost viewing space is relatively small and is substantially off-set by the substantial reduction of constructions costs.

It should also be appreciated that the provision of the arches also adds to the intrinsic value of the building package in many respects. In many applications, it is necessary to introduce other articles within the space, such as lighting, cameras, banners, ventilation and other intruding apparatus.

Thus, in many situations where totally open space is provided, some blind spots are later introduced due to the inclusion of such apparatus. In the present embodiment, the presence of the arches within the operational space may be used to advantage, in that they provide suitable securing locations for internal apparatus. In addition, areas for hospitality and sky boxes may be secured to the arches at suitable locations. An attraction of the preferred embodiment is that by using the provision of the arches at higher locations for the attachment of sky boxes and similar structures, it is possible to include these provisions without further reducing seat capacity. It is also appreciated that in many applications private boxes provide a substantial revenue stream, particularly when exploited for corporate hospitality etc. Figure 5 As previously stated, the arches 401, 402, 403 and 404 are temporarily held by stabilising cables. Thus, with all of the arches in place, a as network of stabilising cables exists so as to maintain the integrity of the structure during the application of its roof in the form of a tensile membrane.

Figure 6 After the parabolic arches have been temporarily secured as illustrated in Figure 5, sky boxes and similar structures are introduced as illustrated in Figure 6. In the preferred embodiment, these boxes are prefabricated off-site. An example 601 of a sky box is shown being lowered into position by means of a crane 602. Thus, a first sky box 601 is lowered and restrained into position, "hereafter similar boxes may be introduced at appropriate locations.

0 Figure 7 After all of the sky boxes and similar equipment have been introduced into the arena space (in a preferred embodiment) fabric membrane panels 701, 702 and 703 are assembled together at floor level, that is to say, over the concrete terraces. While remaining in this resting position (on the arena floor) edges 704 are pre-tensioned to the perimeter wall 301. In order to get the membrane into the air, curved members are secured to the membrane at positions where the membrane will contact the parabolic arches.

Figure 8 A preferred fully constructed embodiment is illustrated in Figure 8.

Parabolic arches support a tensile membrane that is in contact with the arches over a central region of the membrane. Thus, the membrane extends away from the arches over a peripheral region of the membrane to be secured in tension at its edges. In this way, the membrane defines an anticlastic surface.

Figure 9 A cross-sectional view of the fully assembled structure is illustrated in Figure 9. Ground level is illustrated at 901 so it can be appreciated that a proportion of the active floor area is below ground level with the parabolic arches being secured at ground level. Over a central region the tensile membrane is supported by the parabolic arches. However, at the ends of the arches the membranes extend away thereby increasing overall floor space.

Figure 10 A representation of an end wall of the structure is illustrated in Figure 0 10. The structure provides an aesthetic natural looking curve which should minimise its environmental impact compared to many existing structural designs. However, the features also provide substantially all of the functionality associates with existing arenas and similar constructions.

It is generally understood that arenas are multipurposed venues which are required to accommodate a wide variety of events. Typically, between eight thousand seats are provided with the majority of existing arenas providing typically twelve thousand seats. In order to accommodate optimum viewing sight lines, seats must have a severe rake which requires walls of up to eighteen metros in height. Furthermore, to avoid the "tunnel" effect of long so buildings, typical arena structures are sixty to eighty metros in span to provide an equality of viewing distances.

The roof of an arena building is required to suspend ventilation, heating and air conditioning, house lights, access passageway for maintenance and other suspended loads such as lighting, rigs and props etc. as With the extreme span of the roof, this requirement to accommodate suspended loads, in addition to environmental loads of wind and snow, results in a very expensive construction, typically using long span truss steel members or cable supported fabric membranes. However, a typically arena features extremely high walls to accommodate the rake of the seating inside and such walls, irrespective of the roof construction, are expensive to build and install.

The combination of an expensive long span roof and high walls means that the designer of an arena is limited in scope of design and in unable to vary the fundamental form. The present preferred embodiment therefore aims to provide a solution to this problem in which the fundamental requirements are met but at the same time the cost of construction is reduced o substantially.

In the preferred embodiment, a fabric membrane is used with an anticlastic form which is supported for a considerable contact distance along supporting parabolic arches. The parabola is a form which is intrinsically capable of accepting loads naturally and thereby reducing manufacturing costs. The parabolic arches provides support for the fabric membrane roof while keeping the base of the arches outward of the centre of the arena. The arches are erected and stabilised temporarily prior to the membrane arriving on site. The arches do intrude into the main space of the arena and do reduce the number of seats that may be provided behind the arches.

However, this is considered to be acceptable due to the significant cost reductions provided.

The arches are used as an intrinsic part of the building package. They can support suspended sky boxes (hospitality rooms) which would otherwise reduce the seating capacity. In addition, they may also be used for supporting ventilation and electrical ducts at a point where they are most effective. They may also support advertising banners, broadcast screens and lighting. Thus, the design package provides substantially all of the features of a typical long span arena roof while utilising the economies of a shorter span parabolic arch.

Fabric membranes are inexpensive primarily due to their pre fabrication off site. However, it is desirable to establish efficient erection procedures otherwise there is a risk that the economic gains may be lost.

Furthermore, it is also undesirable to work at high levels off the ground during the installation process.

In the preferred embodiment the membrane roof is assembled at ground level and hoisted substantially in one piece to roof level thereby reducing assembly times dramatically. Preferably, the membrane roof uses PVC coated polyester or PTFE coated glass. The membrane is reinforced with cable elements at regular intervals and the cable elements work in tandem with the membrane form to provide stiffness and stability against catastrophic failures in the event of an emergency due to unforeseen or abnormal situations.

After the site has been prepared and the arches have been erected and made stable by temporary cables, the membrane is laid out and raised to the service position. In known cable nets supported membranes, the cable net is hoisted into the air using techniques similar to that deployed in the construction of suspension bridges. These techniques require workmen to operate at high levels above the ground (high level riggers) who are required to perform many hours of lifting, connecting and tensioning the cables prior to fixing onto them a membrane, panel by panel on to the cable net. The membrane panels need to be pre-tensioned to the cables at all points which again introduces a lengthy procedure.

In the construction of a structure embodying the present invention, a membrane is attached to cables on the floor of the construction site and hoisted into a service position by a series of curved ridge members. The curved members allow the membrane to be pre-tensioned at floor level to both the perimeter wall of the building and to the curved ridge member. To fasten and pre-tension the membrane at a height of thirty metres is a difficult and costly operation. However, in accordance with the preferred embodiment, the process is much faster and more economical. The membrane is hoisted into the service position complete with curved ridge members which attach to the main structure arches which are designed to accept them and, "hereafter, they become an integral part of the structural 0 arch.

The main cost in known constructions for conventional arenas is the building the walls. The higher the walls, the greater the cost. Furthermore, working at height increases site cost exponentially. The loads from the roof to the top of the perimeter retaining wall do not change substantially with an increase in height but the forces at the base of the wall do increase substantially with the wall heighVstructure span ratio. However, in a preferred embodiment, the wall height is reduced by sinking the floor of the arena below ground level. This results in a building which fulfils all the major requirements of a multi- purpose arena but at much reduced cost.

Excavation of a central area of the arena may initially appear to be an expensive solution but when compared with the total cost of using higher walls it becomes an acceptable solution. Excavated material may be saved from expensive removal from site by using the material to fill against the outer walls and covering with a grass bern.

Additional benefits come from a reduced profile in the surrounding area. In addition, this facilitates access to seats for elderly, disabled and young patrons who are now approaching the seats from ground level.

Furthermore, the provision of a concourse is important for the generation of revenue through concessionary sales.

Claims (22)

1. Claims 1. A building structure having a plurality of substantially

   parabolic arches, a tensile membrane placed over said arches such that said membrane is in contact with said arches over a central region of said membrane, wherein said membrane extends away from said arches over a peripheral region of said membrane and is secured in tension at its edges so as to define an anticlastic surface.
2. 2. A structure according to claim 1, wherein a peripheral wall is built to present an upper wall surface above ground level and the edges of said membrane are secured to said upper wall surface.
3. 3. A structure according to claim 1 or claim 2, wherein a central floor area under a central region of said structure is excavated below ground level.
4. 4. A structure according to claim 3, when dependent on claim 2, in which material excavated to create said central floor is placed around an outside surface of said peripheral wall.
5. 5. A structure according to any preceding claim, wherein a central floor area is configured for the performance of a viewed activity and inclined seating is provided around said central floor area for viewers of said viewed activity.
6. 6. A structure according to claim 5, wherein a private viewing box is secured to a parabolic arch above said inclined seating.
7. 7. A structure according to claim 5 or claim 6, wherein ends of said parabolic arches are secured at arch locating bases, wherein said inclined seating is positioned both in front of said arch locating positions and behind said arch locating positions.
8. 8. A structure according to claim 7, wherein said arches extend through the structures floor at interface positions outside said central floor area.
9. 9. A structure according to claim 8, wherein said interface positions are above ground level.
10. 10. A structure according to claim 9, having passageways under a main floor to the outside of said parabolic arches.
11. 11. A method of building a structure, comprising the steps of establishing a plurality of parabolic arches; applying a membrane over said arches such that said membrane is in contact with said arches over a central region of said membrane; applying tension to said membrane such that said membrane extends away from said arches over a peripheral region of said membrane; and securing said membrane at its edges so as to define an anticlastic surface.
12. 12. A method according to claim 11, further comprising the steps of building a peripheral wall to present an upper wall surface above ground level such that the edges of said membrane are secured to said upper wall surface.
13. 13. A method according to claim 11 or claim 12, further comprising a step of excavating a central floor area below ground level.
14. 14. A method according to claim 13, wherein excavated material is placed around an outside surface of a perimeter wall.
15. 15. A method according to claim 11, wherein inclined seating is provided around a central floor area for viewers of a viewed activity.
16. 16. A method according to claim 15, wherein a private viewing box is secured to a parabolic arch above said inclined seating.
17. 17. A method according to claim 15, wherein ends of said parabolic arches are secured at arch locating bases and inclined seating is positioned in both in front of said arch locating positions and behind said arch locating positions.
18. 18. A method according to claim 17, wherein arches extend through floor structures at interface positions outside of said central floor area.
19. 19. A method according to claim 18, wherein said interface positions are above ground level.
20. 20. A method according to claim 19, wherein passage ways are located under a main floor to the outside of the parabolic arches.
21. 21. A building structure substantially as herein described with reference to the accompanying Figures.
22. 22. A method of constructing a building substantially as herein described with reference to the accompanying Figures.