BACKGROUND OF THE INVENTION

/•*-- 1. Field of the Invention

This invention relates to a space frame.

5 . Description of the Prior Art

Space frames are widely used particularly in situations where it is required to erect a cover over an extensive area with a minimum of pillars and maximum of uninterrupted floor space. A space frame is usually

10 of double-layer type, consisting of spaced upper and lower grids of longitudinal and lateral chords, the nodes, or junctions of chord members, of the upper and lower grids being interconnected by oblique struts or braces. The two grids are relatively displaced, both

15 laterally and longitudinally so that, except at the periphery of the upper grid, each node of either grid is equidistant from, and connected by oblique struts to, four nodes of the other grid. At each of these nodes, then, provision must be made for the firm interconnect-

20 ion of intersecting chords and a series of oblique struts. Tubular members are generally to be preferred for the chords and the struts, and it is desirable that at each node the axes of the longitudinal and lateral chords, and of the struts, should intersect. Space frames which

25 satisfy these requirements generally have connectors and chord and strut members which are expensive to make and laborious to instal.

BRIEF SUMMARY OF THE PRESENT INVENTION The present invention has been devised with the

30 general object of providing a space frame of the type described in which the chord and strut members may be simply and economically manufactured and may be quickly and easily interconnected rigidly and in optimum relat¬ ionship.

35 With the foregoing and other objects in view, the invention resides broadly in a space frame of the type having spaced upper and lower grids of longitudinal and

lataral chords, the nodes of the upper and lower grids being interconnected by oblique struts, wherein at a node, substantially vertical attachment plates at the ends of longitudinal and lateral chord sections are disposed in a cruciform assembly; flanges, per¬ pendicular to each other, at the ends of oblique struts, are engaged in the angles of the cruciform assembly; and fasteners secure together flanges of succeeding struts and interposed attachment plates of the cruciform assembly. The longitudinal and lateral chords are preferably tubular, the attachment plates being flattened portions at the ends of the longitud¬ inal and lateral chord sections. Preferably the struts also are tubular, each having its end flatten- ed and angled to form the said perpendicular flanges which meet along a line oblique to the axis of the main tubular part of the strut. Other features of the invention will become apparent from the following description. BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS In order that a preferred embodiment of the invention may be readily understood and carried into practical effect, reference is now made to the accomp¬ anying drawings, wherein:- FIG. 1 is a diagrammatic plan view of part of a building including a space frame according to the invention,

FIG. 2 is a side elevational view of a node of the upper grid of the space frame, for example the node in circle 2 of FIG. 1 ,

FIG. 3 is a plan view of the node shown in FIG.

2,

FIG. 4 is a view from below the node, FIG. 5 is a perspective view of an end portion_ of one of the oblique struts of the space frame, and

FIG. 6 is a sectional view taken along line 6-6 in FIG. 1 , to larger scale than FIG. 1 but of smaller scale than FIGS. 2, 3 and 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The space frame illustrated has an upper grid of longitudinal chords 10 and lateral chords 11, a lower grid of longitudinal chords 12 and lateral chords 13, and oblique struts 14 interconnecting the nodes or chord intersections of the upper and lower grid. The space frame is supported horizonta¬ lly within an external wall 15 including vertical space frame supports 16 which serve also as glazing mullions. The space frame supports floor panels 17 and below it there are installed ceiling panels 18.

At the space frame upper grid node shown part¬ icularly in FIGS. 2, 3 and 4 of the drawings, a longit¬ udinal chord member 10, two sections 11 of a lateral chord and four oblique struts 14 are rigidly inter- connected, all of these members being of round-section metal tube of similar diameter.

At the node the longitudinal chord member 10 is flattened to form a vertical connector plate 19. The nodal ends of the lateral chord sections 11 are also flattened to form vertical connector plates 20 which are in alignment and meet perpendicularly the opposite sides of the middle of the connector plate 19, in a cruciform assembly.

The four oblique struts 14 are similar, each being deformed at both ends by metal pressing operat¬ ions to flatten the tube and shape the flattened part to an angle member of which the two flanges 21 are perpendicular, their junction line 22 being oblique to the axis of the main tubular part of the strut. Each of the flanges 15 is formed with two bolt holes 23-

- Bolt holes (not shown) are also formed through the vertical connector plate 19 of the longitudinal chord member 10, and through each of the vertical conn¬ ector plates 20 of the lateral .chord sections 11. These bolt holes are so located that when the struts 14 are positioned as shown, each with its deformed and angled end within one of the angles of the cruciform assembly of the flattened vertical attachment plates of the long¬ itudinal and lateral chords, bolts 24 may be engaged in aligned bolt holes in the strut flanges 15 and in the interposed attachment plates 13 and 14 of the chord ' members and engaged by nuts 25 to secure the whole assembly rigidly together. The parts are so made and arranged that, as indicated by chain-broken lines in FIG. 2, the axes of the chord members and of the strut members intersect at a single point.

Instead of the lateral chords of the space frame being made in sections flattened at the ends, each may be flattened at each node, similarly to the longitudinal chord members, one of the flattened parts being slotted from above, the other slotted from below, so that at each node the longitudinal and lateral chord members are inter- fitted, their axes in a common plane.

Alternatively, the longitudinal chords, as well as the lateral chords, may be composed of a number of similar sections, each flattened and formed with bolt holes at both ends, so that at each node two longitudinal chord sections and two lateral chord sections are brought together in a cruciform assembly and are secured together by being bolted between pairs of flanges 21 of the struts 14.

In the space frame illustrated the sides and ends of the upper grid extend beyond the lower grid and at each of the peripheral nodes of the upper grid (except- ing the corner nodes) two oblique struts only are conn¬ ected.

At these nodes, simple fish-plates (not shown) are bolted at the outer sides of the nodes. At the corner nodes of the upper grid, from which a single oblique strut leads, simple angle brackets (not shown) are bolted outside the corners.

As all of the strut members of the space frame may be identical, all longitudinal chords of each grid may be similar, and all lateral chord sections of the space frame may also be similar, the various members used in the construction may be simply and economically produced, and quickly bolted together without any high degree of skill being required. If the longitudinal chords as well as the lateral chords are made in sections, the whole space frame may be erected of only two basic types of structural members, that is to say, of similar chord members and similar struts.

The floor panels 17 may be of cast reinforced concrete construction, square in plan view and, as shown in FIG. 6, each of greatest depth at the middle, reducing in depth to all four sides where they are supported on a grid of floor panel supports 26 of inverted T-section, welded or otherwise secured on the upper grid. The ceiling panels 18, which may be of fire-resisting acoustic material, are also of square shape and are supported at their edges by a grid of

T-bars 27 fixed in any suitable way below the lower grid of the space frame.

If the space frame is not required to support a roof or ceiling, node caps, as shown in FIG. 2 at 28, may be applied to the space frame nodes. The cap illustrated is of cylindrical shape, closed at its top and formed from the bottom with slots 29 shaped to fit to the nodal ends of the chords and struts. Similar caps may be inverted and applied to the nodes of the lower grid, the caps of upper end lower grids being secured in any suitable way.