ES3049633T3 - Roofing structure - Google Patents

Abstract

A roof beam for a temporary structure is shown. This beam comprises a first elongated element and a second elongated element, each with a rectangular cross-section with a hollow center, and with length, width, and depth. The first elongated element has, at two adjacent corners of its rectangular cross-section, a first longitudinal connector comprising a channel that closes from the hollow center of the first elongated element and opens outward through a neck narrower than the channel. The second elongated element has, at two adjacent corners of its rectangular cross-section, a second longitudinal connector comprising a rib projecting from the neck of a complementary first connector and a flange on the rib secured within the channel of said connector. Furthermore, the first and second elongated elements are configured and arranged, respectively, such that the first and second connectors interconnect, with the second connector fitting within the first, so that the elongated elements are coupled to form the roof beam.

Description

[0001] DESCRIPTION

[0003] Roofing structure

[0005] The present invention relates to a roof beam for a temporary building. The present invention also relates to a method of manufacturing a roof beam.

[0007] Temporary buildings may be required, but not exclusively, for: events, such as concerts (with sound staging) and conventions; educational purposes in schools and colleges; sports facilities (where it is especially desirable to be able to provide an unobstructed area the size of a football field); retail purposes; training; military buildings, such as a temporary (and possibly camouflaged) aircraft hangar; vertical farming; humanitarian needs; and multifunctional storage for businesses, including customs warehousing. Those skilled in the art will appreciate that most, if not all, of these uses will require a completely open area under the roof, meaning that roofing structures must be supported only at their ends, with no intermediate support legs encroaching on the covered area. Furthermore, the roofing structure must be strong enough to support the lights, screens, speakers, lifting equipment, and other items, which are often heavy (perhaps more than 3 tons).

[0009] The need for a roof structure to be strong, especially when it has to span a large area of, say, 100 m without intermediate supports, presents a design problem, since stronger materials tend to be heavier. Thus, as an example, structural steel has a tensile strength of around 500 MPa and a density of around 8 g/cm3, while aluminum alloy is much lighter, at less than 3 g/cm3, but its tensile strength is less than 300 MPa.

[0011] One way to solve this problem in temporary buildings—which must be lightweight for portability—is to use extruded aluminum alloy for a roof beam in the form of a hollow box section. To span large areas, the roof beam is known to be reinforced, for example, by means of a reinforcing profile that slides and fits snugly within the box section of the roof beam. This increases the strength of the beam, but at the cost of increasing its weight.

[0013] Document DE 27 19490 A1 discloses a composite material beam comprising a first and a second elongated member that are coupled together.

[0015] It is an object of the present invention to reinforce a roof beam, such as one formed from extruded aluminum, in such a way that the gain in strength is proportionally greater than the gain in weight. The invention aims, in particular, to provide a roof beam that is both stronger and lighter than those using a reinforcing profile slid into a box section, as described above.

[0017] Thus, according to a first aspect of the invention, a roof beam is provided for a temporary building where:

[0019] said roof beam comprises a first elongated member and a second elongated member, each comprising a rectangular box section with a hollow center having a length, a width and a depth;

[0020] the first elongated member is provided at each of the two adjacent corners of its box section with a first connector extending lengthwise and comprising a channel closed from the hollow center of the first elongated member and open outwards through a neck narrower than the channel; the second elongated member has at each of the two adjacent corners of its box section a second connector extending lengthwise and comprising a rib projecting through the neck of a complementary first connector and a flange on said rib held within the channel of the complementary first connector; and

[0021] The first elongated member and the second elongated member are respectively configured and arranged so that the first and second connectors interconnect, with the second connector being a close fit within the first connector, so that the first and second elongated members couple together to form said roof beam.

[0023] It will be seen that, like the previously known reinforcement arrangement mentioned above, the present invention provides a roof beam comprising two elongated members, each having a hollow box section profile. However, instead of one member sliding inside the other, as in the previously known arrangement, the invention positions the reinforcing member (the second elongated member) alongside, rather than inside, the first elongated member. As will be described later herein, along with other features of the invention, it is both stronger and lighter than the prior arrangement.

[0025] In a second aspect, the invention extends to a roof truss comprising two roof beams according to the first aspect of the invention, wherein said two roof beams are arranged parallel to each other, one above the other, and the upper roof beam has its said second elongated member below its said first elongated member and the lower roof beam has its said second elongated member above its said first elongated member, with bracing members extending between and secured to said second elongated members.

[0027] The invention extends to a method of manufacturing a roof beam according to the first aspect of the invention or a truss according to the second aspect of the invention.

[0029] Other features of the invention will be evident from the following description, which is given only by way of example and with reference to the accompanying drawings, which are schematic and in which:

[0031] Figure 1 illustrates in cross-section two hollow box sections extruded from aluminum alloy, one of which is configured and arranged to fit tightly within the other, in order to form a reinforced roof beam, as previously known;

[0032] Figure 2 illustrates in cross section a roof beam embodying the present invention;

[0033] Figure 3 is an isometric view of two roof truss beams of the type shown in Figure 2; and Figure 4 shows, enlarged from Figure 3, a detail of the roof truss of Figure 3.

[0035] Referring first to Figure 1, it shows the previously known first and second roofing profiles 100 and 102, each extruded from aluminum alloy and having a box section with a hollow center. The first profile 100, in lightweight structures, can be mounted at its opposite ends on a support indicated schematically by dashed lines in 104, to form a roof beam to support a fabric roof. For this purpose, the first profile 100 has channels 106 at its corners to receive Keders for securing the fabric roof in place. (The Keders are not shown in the drawings, but those skilled in the art will know that they slide into the channels 106 to extend along the length of the roof beam and have flaps which, in use, extend through the narrow neck 106 of the channels 206 to secure to the fabric, either by sewing or, preferably, welding.)

[0037] For heavier structures and especially for longer spans (say L > 10 m), profile 100 is reinforced by sliding profile 102 into the hollow center of the box section of profile 100, so that it extends along the length of profile 100. Profiles 100 and 102 are respectively configured and arranged so that profile 102 is a tight fit inside profile 100. Thus:

[0039] - profiles 100 and 102 are the same length;

[0040] - profile102 has an external width W2e slightly less than the internal width W1e of profile100;

[0041] - the profile102 has an external depth D2e slightly less than the internal depth D le of the profile100; and - the corners of the profile102 are arc-shaped with inward-facing curves108 to accommodate the projection of the channels106 into the hollow box section of the profile100.

[0043] Instead of the arrangement in Figure 1, in which one roofing profile slides inside another to provide a composite roof beam, in the present invention, two profiles (referred to herein as a first elongated member and a second elongated member, to more clearly distinguish the invention from the prior art of Figure 1) are connected along their length, one above the other. This is illustrated by Figure 2, which shows in cross-section a composite roof beam200 comprising said first elongated member202 and said second elongated member204, each extruded from aluminum alloy.

[0044] The first elongated member 202 comprises a hollow box section like that of profile 100 in Figure 1, with channels 206, 208, 210, and 212 at its four corners. The two lower channels 210 and 212, as seen in Figure 2, receive Keders for holding a fabric roof in place. (It may be noted here that the composite beam 200 can, in use, be inverted with respect to Figure 2, so that the second elongated member 204 is below the first elongated member 202 and the Keder-receiving channels 210 and 212 are on top of the composite beam 200.) The upper channels 206 and 208, as seen in Figure 2, do not receive Keders but are used for a different purpose, as will be described hereafter.

[0046] The second elongated member204 comprises a rectangular hollow box section with its sides slightly thickened in214 for extra strength. The first and second elongated members202 and204 are of equal length and equal width. The second elongated member204 has a depth slightly less than half that of the first elongated member204.

[0048] As seen in Figure 2, the second elongated member 204 has at its two lower corners arched ribs 216 and 218 that extend outwards and then curve back to extend into the upper channels 206 and 208 of the first elongated member 202, the ribs 216 and 218 being sized and arranged to fit through the narrow necks of the channels 216 and 218. The free ends of the ribs 216 and 218 are formed with enlarged heads 220 and 222 respectively that do not fit through the necks of the channels 216 and 218. Rather, each of the rib-head formations 216, 220 and 218, 222 is configured and arranged so that the heads 220 and 222 are each close against the<inside of their respective channels>206<and 208.>

[0049] To couple the first and second elongated members 202 and 204 together to form the composite beam 200, they are first placed end to end, when the head-ribbon formations 216, 220 and 218, 222 are aligned with the respective channels 206 and 208. Next, the first and second elongated members 202 and 204 are moved relative to each other in the lengthwise direction, so that the head-ribbon formations 216, 220 and 218, 222 slide through the respective channels 206 and 208. This relative lengthwise movement is continued until the ends of the first and second elongated members 202 and 204 coincide with each other and the composite beam 200 is formed. Next, the opposite ends of the composite beam200 are secured to supports that extend vertically to support a raised fabric roof connected to the beam200 by Keders in the usual way.

[0051] The composite beam200 is both lighter and stronger than the previously known reinforced beam formed as described above in this document with reference to Figure 1 by sliding the profile102 into the profile100, as will be explained at this time.

[0053] In each case, the weight of the beam is proportional to its cross-sectional area. Rounded, the aggregate cross-sectional area of the profiles 100 and 102 of Figure 1 (and, therefore, of the previously known composite beam formed by sliding one into the other) is 75 cm². The aggregate cross-sectional area of the composite beam 200 of Figure 2, with nominal wall thicknesses equal to those of the profiles 100 and 102, is 62 cm². It follows that the weight per unit length of the composite beam 200 is almost 20% less than that of the previously known beam. Furthermore, the lighter roof beams do not require such strong supports, offering a further reduction in the amount of aluminum (or possibly other material) required.

[0055] Importantly, the weight reduction resulting from the use of the invention also provides a substantial environmental benefit by simultaneously reducing energy consumption and carbon emissions, because aluminum production is both energy-intensive and carbon-intensive. Aluminum production requires approximately 17,000 kWh of electricity per tonne; and carbon emissions from aluminum production exceed 6 tonnes of CO2e (carbon dioxide equivalent, including perfluorocarbons) per tonne of aluminum.

[0057] Considering the strength of the composite beam200, building safety dictates—by design and/or regulations—that the deflection must not exceed a specified amount in use, which, in turn, defines a safe working load for the beam. As is well known, about a specified axis, the deformation of a beam under a given load is inversely proportional to the area moment of inertia about that axis. The well-known composite beam formed by fitting the profiles100 and102 of Figure 1 together has an area moment of inertia calculated as ly = 5.197 cm⁴. Conversely, the composite beam 200 embodying the invention has a calculated area moment of inertia of 8.265 cm4. It follows that, under a given load, the deformation of the beam 200 is much lower than that of the known composite beam formed by fitting the profiles 100 and 102 of Figure 1 together. Expressed alternatively and more significantly, the composite beam 200 can safely carry a much higher working load than that of the prior art.

[0059] It should be understood that a composite beam embodying the invention may have dimensions somewhat different from those indicated by the drawings thereof. And the weight reduction and the strength increase may be balanced against each other according to specific requirements.

[0061] Figures 3 and 4 illustrate a roof truss combining two roof beams according to the invention. As shown in Figures 3 and 4, the truss 300 comprises an upper roof beam 302 and a lower roof beam 304, each similar to the roof beam 200 of Figure 2 and arranged parallel to it. The lower roof beam 304 has the same orientation as the beam 200, as shown in Figure 2, so that the first elongated member 304a, which has a substantially greater depth than the second elongated member 304b, is below the second elongated member 304b. The upper roof beam 302 is inverted with respect to this, i.e., with the deeper first elongated member 302a above the shallower second elongated member 302b.

[0062] In this way, the second elongated members302by304b face each other.

[0064] The second elongated members 302 and 304 are formed respectively to receive the upper and lower ends of braces comprising orthogonal braces 306 and (for triangulation) diagonal braces 308. The ends of the braces 306, 308 are secured to the second elongated members 302 and 304 by means of rivets, as indicated in Figure 4. It is understood that the number of braces and their spacing will depend on the length of the truss, of which only a short part is shown in Figure 3.

[0066] Calculations indicate that a truss as described above, comprising two roof beams of the type shown in Figure 2, can be up to 34% lighter than one comprising two roof beams of the shape shown in Figure 1, thus offering further reductions in energy consumption and carbon emissions.

[0067] It shall be understood at this time that a roof beam or truss embodying the invention can be manufactured by a method:

[0069] wherein a first elongated member and a second elongated member are provided, each having a hollow center along its length and, outside of said hollow center, a pair of sliding elements extending along the length of the respective elongated member;

[0070] wherein the sliding elements in the second elongated member are configured and arranged to slide into the sliding elements in the first elongated member; and

[0071] wherein the sliding elements fit together and the second elongated member slides along the length of the first elongated member and is secured to it.

[0073] This allows the construction of a roof (a) of very large extent (say, 100 m) without intermediate supports and (b) capable of carrying very large loads (several tons, compared to only a few hundred kilos up to this point).

[0075] By means of the invention, the internal suspended payload (i.e., the weight of equipment that can be hung from any point on the ceiling) is greatly increased. The calculations presented indicate that a central load of more than 3 tons can be hung from the bottom of a truss embodying the invention, with two elongated, hollow members slidably coupled to each other to be adjacent from top to bottom.

[0077] The sliding arrangement not only provides greater strength than up to this point. It also reduces the weight per meter of length; and, by eliminating the need for reinforcing inserts within a roof truss or beam, the weight of the truss or beam (and, in that way, also of the supporting legs) is further reduced, resulting in a further reduction in the weight and material required.

[0079] The invention offers significant advantages in the construction of very large structures requiring high intrinsic strength to accommodate very large spans (up to 100 m) without internal supports and the capacity to carry a large payload. This represents an improvement over existing large structures, which are currently produced primarily from steel profiles. Simultaneously, the invention maximizes internal space while minimizing external impact.

[0081] Finally, it shall be understood that the invention is of particular value for extending the capacity of existing roof beam and truss designs that include Keder connections.

Claims (14)

1. CLAIMS 1. A composite roof beam (200) for a temporary building, wherein: said composite roof beam comprises a first elongated member (202) and a second elongated member (204) to reinforce the first elongated member, each comprising a rectangular box section with a hollow center having a length, a width and a depth; the first elongated member is provided at each of the two adjacent corners of its box section with a first connector that extends lengthwise and comprises a channel (206, 208, 210, 212) closed from the hollow center of the first elongated member and open outwards through a neck narrower than the channel; the second elongated member has at each of the two adjacent corners of its box section a second connector extending lengthwise and comprising a rib (216, 218) projecting through the neck of a first complementary connector and a tab on said rib held within the channel of the first complementary connector; and The first elongated member and the second elongated member are respectively configured and arranged so that the first and second connectors interconnect, with the second connector being a close fit within the first connector, so that the first and second elongated members couple together to form said composite roof beam. 2. The composite roof beam of claim 1, wherein each rib (216, 218) of said second connector is arched in shape and extends outwards from its corner location and then inwards through the neck of the respective first connector. 3. The composite roof beam of claim 1 or claim 2, wherein the box section of the second elongated member (204) has one or both of: a length and width equal respectively to the length and width of the box section of the first elongated member (202); and a depth less than the depth of the box section of the first elongated member. 4. The composite roof beam of claim 3, wherein the depth of the box section of the second elongated member (204) is no more than half the depth of the box section of the first elongated member (202). 5. The composite roof beam of any of claims 1 to 4, which, in use, is supported on columns at its opposite ends, without additional supports between said ends. 6. The composite roof beam of claim 5, configured and arranged to be higher between said ends than at said ends. 7. The composite roof beam of any of claims 1 to 6, comprising an aluminum alloy extrusion. 8. The composite roof beam of any of claims 1 to 7, further comprising additional connectors configured and arranged to fasten the edges of the laminate material extending in the width direction of the composite roof beam to form a roof. 9. The composite roof beam of claim 8, wherein said additional connectors are Keders. 10. A roof truss (300), comprising two roof beams (200) according to any of claims 1 to 9 arranged parallel to each other, one above the other, in use, wherein: The upper of said two roof beams, in use, has its second elongated member (204) below its first elongated member (202); and The lower of said two roof beams, in use, has its second elongated member (204) above its first elongated member (202), with bracing members (306, 308) extending between and secured to said second elongated members. 11. The roof truss of claim 10, wherein the second elongated members (204) are formed to receive the ends of said bracing member (306, 308) within the hollow box sections of said second elongated members. 12. The roof truss of claim 11, wherein said ends of the bracing members (306, 308) are secured within the hollow box sections of said second elongated members by means of rivets. 13. The roof truss of any of claims 10 to 12, wherein some of said bracing members (306, 308) are orthogonal to said roof beams and other of said bracing members are inclined with respect to said roof beams. 14. A method of manufacturing a composite roof beam (200) or truss (300) according to any of claims 1 to 13: wherein the second connectors on the second elongated member (204) are configured and arranged to slide into the first connectors on the first elongated member (202); and the connectors fit together and the second elongated member slides along the length of the first elongated member and is secured to it.