SPACE FRAMES

Abstract: In a space frame with the nodes of top and bottom rectangular grids (10, 11 and 12, 13) connected by oblique struts (14), the longitudinal chords (10, 12) and the lateral chords (11, 13) are top-hat section channels, each with its sides (15) terminating in co-planar side flanges (17), and are oppositely arranged so that at each node the side flanges (17) of a longitudinal chord (10, 12) are towards the side flanges (17) of a lateral chord (11, 13) and are secured together by bolts (19), each of the struts (14) having at its ends attachment plates (20) secured by bolts (21) to nodes of the top and bottom grids.

Description: Title: SPACE FRAMES BACKGROUND OF THE INVENTION (1) Field of the Invention: THIS INVENTION relates to improved space frames. (2) Brief Description of the Prior Art: Space frames have found wide applications as framing units for roofs or floors which are required to span large areas, e.g. in aircraft hangars. However, such space frames are generally relatively complex and require complicated and expensive connectors to join the top and bottom grids and the load-transmitting diagonal struts. Such joints are well suitable for large, heavy-duty space frames, but are unduly expensive for use in lightweight space frames suitable for the construction of, e.g. car- ports, garages and many domestic and industrial buildings. BRIEF SUMMARY OF THE INVENTION It is an object of the present invention to provide a space frame which avoids the need for complex connectors between the chord-frames and the struts. Another aspect of the invention is to provide a space frame to which roofing sheets, or ceiling sheets, or both, may be applied directly without further structural members being required for their support or attachment. Other objects achievable in preferred embodiments of the invention are to provide a space frame which is particularly simple and economical to manufacture from readily available metal sections, which is capable of being quickly and easily assembled, and which is sturdy and durable in use. With the foregoing and other objects in view the invention resides broadly in a space frame having top and bottom rectangular grids, each of lateral and longitudinal chords crossing at nodes, and oblique struts interconnect¬ ing nodes of the two grids, wherein, in each grid, the chords are channels, each with its sides terminating in out-turned substantially co-planar side flanges; the lateral and longitudinal chords are arranged oppositely, the upper, chords with their side flanges lowermost, the lower chords with their side flanges uppermost; and at each node, fastening means secure both sides of the upper chord to both side flanges of the lower chord. Preferably each of the struts is provided at its ends with attachment plates secured, preferably by bolts, at nodes of the upper and lower grid. Other features of the invention will become apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may be readily under¬ stood and carried into practical effect, reference is now made to the accompanying drawings, wherein:- FIG. 1 is a perspective view of a part of a space frame made according to the invention, with parallel upper and lower grids of chord members interconnected by diagonal struts, FIG. 2 is a detail drawing showing the attachment of a diagonal strut to a chord of the space frame shown in FIG. 1, FIG. 3 is a plan view of a node of the upper grid of the space frame, FIG. 4 is a side elevational view of part of a space frame according to the invention, with non-parallel upper and lower grids, FIG. 5 is a sectional view showing the attachment of diagonal struts at a node of an upper grid according to a modification of the invention, FIG. 6 is a sectional view showing the attachment of diagonal struts at a node of a lower grid according to another embodiment of the invention, and FIG. 7 is a sectional view showing the attachment of diagonal struts at a node of a lower grid according to a further modification of the invention. - 3 - DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The space frames illustrated each include a top rectangul-ar gri-d of longitudinal chord members 10 and lateral chord members 11, a bottom rectangular grid of 5 longitudinal chord members 12 and lateral chord members 13, and diagonal strut members 14 interconnecting the nodes or intersections of the top grid with the nodes of the bottom grid, in such a way that the space frame consists of a combination of rectangular-base pyramid constructions. 10 All of the chord members 10, 11, 12 and 13 are of similar roll-formed steel sections of "top-hat" form, each comprising a channel with side walls 15 diverging from the web 16 and leading to outwardly directed substantially co-planar side flanges 17 which, near to their outer edges, 15 are bent through fairly small angles to form stiffening flanges 18. In the top grid, the lateral chords 11, arranged with their channel opening downwardly, their side flanges 17 lowermost, are secured perpendicularly across the 20 longitudinal chords 10 which are reversed, relative to the lateral chords, and have their channels opening upwardly, their side flanges 17 uppermost. In the bottom grid, the lateral chords 13, with their channels opening upwardly, their side flanges uppermost, are secured perpendicularly 25 under the longitudinal chords 12 which are arranged with their channels opening downwardly, their side flanges lowermost. In each grid, the lateral and longitudinal chords are rigidly secured together by four bolts 19 at each node, through the side flanges 17 of the superimposed 30 chords. The diagonal struts 15 interconnecting nodes of the top and bottom grids are of steel tube with flattened end portions forming attachment plates 20. In the embodiments of the invention shown in FIGS 1 to 5 inclusive, these 5 attachment plates 20 are fitted, at the nodes of the top - 4 - and bottom grids, into the chord channels open to receive them, that is to say the upper attachment plate 20 of each strut 14 is engaged in a top grid lateral chord 11, the lower attachment plate 20 of the strut being engaged in a bottom grid lateral chord 13. The attachment plates 20 of the strut are angled, relative to the main unflattened part of the strut, only sufficiently to enable them to lie flat against the appropriate bolique side walls 15 of the chords, to which they are firmly secured by bolts 21. For added rigidily of each connection, the attachment plates are cut obliquely, as shown in FIG. 2, to bear against the webs 16 of the channel chords in which they are inserted and to which they are bolted. Because of the divergency of the side walls 15 of the chords, the attachment plates 20 of the struts will require to be bent through only small angles relative to the main unflattened parts of the struts. In the space frame shown in FIG. 1, the top and bottom grids are parallel, and so all of the struts 14 are of similar length, but in the embodiment shown in FIG. 4 the grids are non-parallel, and so a variety of strut lengths is required. The connections of the struts 14 of the chords at each node may be reinforced by the addition of reinforcing plates 22, as shown in FIG. 5. These plates are pieces of sheet steel angled to lie against the outside faces of the chord side walls and also overlie the side flanges 17, and the bolts 21 securing the struts 14, and the bolts 18 interconnecting the lateral and longitudinal chords, pass through and secure in place the reinforcing plates 22. In the modification shown in FIG. 6, the attachment plates 20 of the struts 14, instead of being bolte'd inside channelled chords, are instead secured by the bolts 19 holding together the lateral and longitudinal chords. In this form of the invention, the attachment plates 20 require to be bent through considerably greater angles to - 5 - the unflattened tubular parts of the struts than in the embodiment before described, and a washer or filler pie.ce 23 is interposed between each of the attachment plates 20 and the chord side flange 17 onto which it is bolted. In the further modification shown in FIG. 7, the attachment plates 20 of the struts 14 are interposed between the side flanges 17 of the crossing lateral and longitudinal chords, and the bolts 19 used to secure these crossing chords together also secure the interposed attachment plates 20. Because of the uppermost surfaces of the space frame, that is to say the webs 16 of the lateral chords 11 of the top grid, and also the lowermost surfaces of the structure, that is, the webs 16 of the lateral chord 13 of the bottom grid, lie in planes unbroken by node connectors, roofing sheets may be applied directly to the top of the space frame, and ceiling sheets may be applied directly under the structure. In the embodiment shown in FIG. 4, the space frame is supported by posts 24, and is made so that its bottom grid is horizontal and its top grid is pitched at an angle to horizontal. Roofing sheets 25 are secured in any suitable manner to the lateral chords 11 of the top grid, and to any supplementary roofing batten 26 that may be required, and ceiling sheets 27 are secured under the lateral chords 13 of the bottom grid. The top-hat section chords will nest to compact form for convenient transport and storage and, because of this configuration, two sections of the roll-formed material may have end portions interfitted and bolted together to form a long chord. Also, any chord may be reinforced at any position by a length of the same material fitted onto, or into, the chord and * *δolted, riveted or otherwise secured in place. The struts, instead of being flattened at their ends to form attachment plates, may instead be of composite form with their main tubular sections welded or otherwise secured to attachment plates. The chords and struts may be of any of a variety of cross-sectional configurations other than that shown. These, and many other modifications of constructional detail and design, which will be readily apparent to persons killed in the art, are considered to lie within the scope and ambit of the invention hereinafter claimed.

Claims: CLAIMS: 1. A space frame having top and bottom rectangular grids (10, 11 and 12, 13) , each of lateral and longitudina chords (11, 13 and 10, 12) crossing at nodes, and oblique struts (14) interconnecting nodes of the two grids (10, 11 and 12, 13), characterized in that in each grid: the chords (10-13) are channels, each with its sides (15) terminating in out-turned substantially co-plana side flanges (17) , the lateral and longitudinal chords (11, 13 and 10, 12) are arranged oppositely, the upper chords (11, 12) with their side flanges (17) lowermost, the lower chords (10, 13) with their side flanges (17) uppermost, and at each node, fastening means (19) secure both side flanges (17) of the upper chord (11, 12) to both side flanges (17) of the lower chord (10, 13). 2. A space frame according to Claim 1 and further characterized in that: each of the struts (14) is provided at its ends with attachment plates (20) secured at nodes of the upper and lower grids (10, 11 and 12, 13) . 3. A space frame according to Claim 2 and further characterized in that: each of the struts (14) has one attachment plate (20) secured within the channel of the upper chord (11) of the upper grid (10, 11) and the other attachment plate (20) secured within the channel of the lower chord (13) of the lower grid (12, 13). 4. A space frame according to Claim 2 and further characterized in that: ^ the fastening means comprise^Ipolts (19) , each through a side flange (17) of an upper chord (11, 12) , a side flange (17) of a lower chord (10, 13), and also through an attachment plate (20) of a strut (14) . A space frame according to Claim 4 and further characterized in that: the attachment plate (20) of the said strut (14) is interposed between the side flanges (17) of the upper and lower chords (11, 12 and 10, 13) . xϊ

Inventors: WALLEN RONALD LEE
Applicants: WALLEN LEONIE RUTH, WALLEN RONALD LEE
Application year: 1982
Main classification: E04B1
IPC codes: E04B1