Joints and structures incorporating same

A joint for joining structural members extending in at least two intersecting planes comprises a pair of outer spaced-apart annular plate members parallel to one of the intersecting planes and sandwiching structural members in that plane, a pair of spaced-apart inner plate members located within the outer plate members and parallel to another of the intersecting planes for sandwiching structural members in the another plane and attachment means for attaching the inner plate members and the outer plate members. The invention also extends to a structure incorporating the joint and modified forms of the joint are disclosed for use on the sides and corners of such a structure.

BACKGROUND OF THE INVENTION 
1. Technical Field 
This invention relates to joints, particularly joints for joining 
structural members extending in at least two intersecting planes, and to 
structures incorporating same. 
The joints of this invention are useful for example in the manufacture of 
so-called "space structures" in which a plurality of structural members, 
usually in the form of tubular members constructed of fibre-reinforced 
plastics material, extending in two or more intersecting planes are joined 
at their ends to form a lightweight assembly. 
2. Description of the Prior Art 
U.S. Pat. No. 4,247,218 discloses a joint having a complex shaped base 
member provided with outwardly extending lugs for attachment to 
longitudinal elements in one plane and faces formed by a convex 
polyhedral-shaped surface including means for connection to diagonal 
longitudinal elements. 
A complex multi-part structural joint is disclosed in U.S. Pat. No. 
4,330,221 and is adapted for both forming and joining composite 
intersecting structural members extending in the same plane. 
The three-part stacked connector of U.S. Pat. No. 4,355,918 includes 
recessed formations between adjacent faces for trapping specially headed 
ends of space frame members. Another joint requiring particular end shapes 
on interconnected girders is disclosed in U.S. Pat. No. 4,480,418 wherein 
the spherical ends of a plurality of the girders are located and retained 
in a joint comprising two substantially hemispherical hollow parts 
connected by a central bolt. 
EP-A No. 0284311 is concerned with a toy or model making structure 
including a joint capable of being dismantled and comprising threadably 
engageable disks each having a plurality of concentric rings for 
engagement by bifurcated ends of elongated link means. 
Examples of other complex multi-part joints are to be found in U.S. Pat. 
No. 3,779,657 and U.S. Pat. No. 4,676,043. 
DISCLOSURE OF THE INVENTION 
This invention provides a joint for joining structural members extending in 
at least two intersecting planes wherein the joint comprises a pair of 
outer spaced-apart annular plate members located parallel to a first one 
of said intersecting planes for sandwiching structural members extending 
in that plane, a pair of spaced apart inner plate members located within 
said outer annular plate members and parallel to another of said 
intersecting planes for sandwiching structural members extending in said 
another plane, and attachment means for attaching said inner plate members 
to said outer annular plate members. 
Conveniently, in one embodiment said attachment means comprises a 
structural member common to said intersecting planes and extended between 
said outer spaced apart annular plate members and said inner plate 
members. The common structural member may extend continuously across the 
inner plate members. The outer annular plate members and the inner plate 
members may be circular plate members and the structural members may 
extend from both sides of the joint in both planes. Preferably, 
reinforcing flanges are provided around both of the inner and outer 
circumferences of the annular plate members. 
In such an embodiment the attachment means may conveniently comprise radial 
flanges at the periphery of the inner circular plate members for 
attachment to the reinforcing flanges on the inner circumference of the 
outer annular plate members. 
Either the outer annular plate members or the inner plate members may be 
semi-circular so that the structural members in the plane of the 
semi-circular members extend from one side only of the joint so that the 
joint is particularly suited for use at the sides of a structure. 
Alternatively, both of the outer annular plate members and the inner plate 
members may be semi-circular so that the structural members extend from 
one side only of the joint in both planes whereby the joint is 
particularly suited for use at the corners of a structure. 
In another aspect this invention provides a structure having a plurality of 
elongated structural members extending in intersecting planes and joint 
means for joining ends of said members wherein each joint means comprises 
a pair of spaced-apart annular plate members located parallel to a first 
one of said intersecting planes for attachment to the external surface of 
the ends of structural members extending in that plane, a pair of 
spaced-apart inner plate members within said outer annular plate members 
and parallel to another of said intersecting planes for attachment to the 
external surface of the ends of structural members extending in said 
another plane, and attachment means for attaching said inner plate members 
to said outer annular plate members.

DETAILED DESCRIPTION OF THE DRAWINGS 
Referring now to FIG. 1, two orthogonally arranged planes AAAA and BBBB 
intersect along a common axis C--C. Two structural members 11a and 12a 
extend radially from an end spaced-apart from a point 13 located on axis 
C--C and in plane AAAA and two structural members 14b and 15b extend 
radially from an end spaced-apart from the same point 13 and in plane 
BBBB. A further structural member 16 extends along axis C--C and through 
point 13. 
The structural members lla, 12a, 14b 15b and 16 are joined by a joint 17 
shown schematically in FIG. 1 and in detail in FIGS. 2 and 3. 
Joint 17 includes a pair of outer spaced-apart annular plate members 18 
located parallel to plane BBBB and sandwiching structural member 16 and 
the ends of structural members 14b and 15b. The annular plate members 18 
are circular and have reinforcing flanges 19 and 20 extending 
perpendicularly from their surface and around both of the inner and outer 
circumferences. 
A pair of spaced-apart circular inner plate members 21 are located parallel 
to plane AAAA and centrally within the outer annular plate members 18, and 
are oriented perpendicular thereto to sandwich structural member 16 and 
the ends of structural members lla and 12a. 
Thus, in the illustrated embodiment, structural member 16 is common to both 
planes AAAA and BBBB (FIG. 1) and extends continuously between the outer 
annular plate members and the inner plate members to provide a convenient 
attachment between the outer plate members 18 and inner plate members 21. 
The outer annular plate members 18 support the ends of structural members 
such as 14b and 15b extending in plane BBBB and the inner plate members 21 
support the ends of structural members such as lla, 12a extending in plane 
AAAA. 
In an application of a joint 17 for joining the structural members of a 
space structure all of the parts of the joint 17 and the structural 
members are manufactured of fibre-reinforced thermoplastic materials. As 
illustrated the structural members are tubular and have a square cross 
sectional shape. 
The respective plates of joint 17 and the structural members 11a, 14b etc. 
are all manufactured from a desired number of laminae of fibre-reinforced 
thermoplastic material to build up a required thickness of material, the 
components being hot press consolidated with a co-moulded adherent polymer 
layer incorporated in those parts of the respective components that are to 
be joined together on assembly. 
Final assembly is achieved by fusion bonding of the adherent polymer layers 
on the surfaces of mating components to provide a strong lightweight 
joint. 
It will be understood that further structural members in both planes such 
as are shown for example in broken line at 22b in FIG. 2 and at 23a in 
FIG. 3 are easily accommodated by the joint 17. Similarly, the structural 
members need not all extend radially from the common central point 13 and 
can for example be located generally tangentially thereto as illustrated 
in broken line at 24a in FIG. 3. 
The embodiment of FIG. 4 illustrates a modified form of attachment means. 
Thus structural member 16 does not extend across the inner plate members 
21 and, instead, outwardly extended flange portions 25 are provided at 
least on the peripheral parts of the inner plate members 21 adjacent to 
the inner flanges 20 of the outer annular plate members. The flanges 20 
and 25 are joined by any suitable means such as by bonding. 
FIG. 5 illustrates a joint 17 similar to that of FIGS. 2 and 3 except that 
the outer annular plate members 18 are generally semi-circular and the 
structural members (e.g. 15b) in the plane of the outer plate members 18 
extend from one side only of the joint in that plane. Such a joint is 
useful at the sides of a structure, and a similar facility can be provided 
by making the inner plate members 21 semi-circular whilst retaining the 
circular outer annular plate members 18. 
FIG. 6 illustrates a joint in which both the inner and outer plate members 
are semi-circular and is useful for example at the corners of a structure 
since the structural members (e.g. 12a and 15b) extend from one side only 
of the joint in both of the perpendicularly opposed planes. 
The embodiment of FIG. 7 is useful in a structure having a diagonal 
structural member as shown for example at 26 to be connected at a joint 17 
with structural members such as 16, 11a, 14b and 15b lying in 
perpendicularly disposed planes as hereinbefore described. This is 
facilitated by the portions of the inner plate members 21 at one side of 
the annular outer plate member 18 being at an angle with respect to its 
remainder in order to sandwich the diagonal structural member 26. In a 
further unillustrated embodiment the angled portion of inner plate members 
21 may comprise a bifurcated angled portion to attach diagonal structural 
members in two planes. 
Thus, the joint 17 of this invention provides direct load paths across the 
joint by transferring all structural member loads in one plane through the 
inner plate members 21 and transferring all structural member loads in the 
other plane through the outer annular plate members 18. Loads are 
transferred between the two pairs of plates by attachment means which in 
the embodiment of FIGS. 2 and 3 comprises the common structural member 16 
and in the embodiment of FIG. 4 comprises the mated flanges 20 and 25. 
The joint 17 therefore provides a lightweight, high strength and extremely 
versatile means of joining structural members extending in at least two 
intersecting planes. 
Whilst one embodiment has been described and illustrated it will be 
understood that many modifications may be made without departing from the 
scope of the invention. For example common structural member 16 need not 
be continuous across inner plate members 21 provided that enough bond 
length is provided to transfer loads across the plates and the inner plate 
members 21 can be attached to the outer annular plate members 18 by any 
other suitable attachment means. The joint may be of any suitable material 
and may be used for joining structural members of other materials, and in 
such embodiments the parts can be attached using any appropriate means 
such as bonding, bolting, riveting etc. One or more additional pairs of 
annular plate members outside the annular plate members 18 can be provided 
and can be used to join structural members in other intersecting planes, 
and the outer annular plate members 18 and the inner plate members 21 can 
be other than circular in shape and may for example be rectangular.