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Claims  |
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What I claim is:
1. A support structure, comprising:
(A) a first upper ring member having a diameter;
(B) a second upper ring member having a diameter,
(C) a lower foundation having a diameter greater than the diameters of said
first and second upper ring members; and
(D) a plurality of integral structural members extending radially from each
of said upper ring members, said structural members having a first lateral
end and a second lateral end, wherein each of said structural members are
secured adjacent their first lateral ends to either said first or second
upper ring members, and wherein said structural members are secured
adjacent their second lateral ends to said lower foundation, and wherein a
portion of said structural members distal their first and second lateral
ends overlaps a portion of adjacent structural members between the upper
ring members and the lower foundation.
2. The support structure of claim 1, wherein said integral structural
members are elastically modified to form a generally S-shaped
configuration between said upper ring members and said lower foundation.
3. The support structure of claim 1, wherein said diameters of said first
and second upper ring members are of a generally similar diameter.
4. The support structure of claim 1, wherein said overlapping structural
members are secured at overlapping points with fasteners.
5. The support structure of claim 1, wherein said structural members
connected to said first upper ring are connected adjacent a lower surface
thereof.
6. The support structure of claim 1, wherein said structural members
connected to said second upper ring are connected adjacent an upper
surface thereof.
7. A support structure, comprising:
an upper member;
a lower foundation; and
a plurality of integral elastically deformed structural members rigidly
secured to said upper member and said lower foundation, wherein the
integral structural members radially extend at angular intervals from the
upper member, and wherein a portion of adjacent integral structural
members overlap a portion of adjacent structural members between the upper
member and the lower foundation.
8. The support structure of claim 7, wherein a first plurality of
structural members are connected to said upper member at a first vertical
location thereof and wherein a second plurality of structural members are
connected to said upper member at a second vertical location thereof, said
second vertical location being lower than said first vertical location.
9. The support structure of claim 7, wherein said upper member comprises a
first upper ring member having a diameter and a second upper ring member
having a diameter.
10. The support structure of claim 9, wherein said plurality of structural
members are alternately secured to said first upper ring member and said
second upper ring member.
11. The support structure of claim 10, wherein said diameters of said first
and second upper ring members are of a generally similar diameter.
12. The support structure of claim 7, wherein said structural members are
secured to overlapping structural members at overlapping points with
fasteners.
13. A process for creating a dome support structure comprising the steps
of:
providing a first upper member, a second upper member, a plurality of
elongated structural members, and a lower foundation;
placing the first upper member over the second upper member in an initial
relative position, said first and second upper members each respectively
including a plurality of said elongated structural members extending
radially outwardly at angular intervals from said ring members, said
structural members having a first and a second lateral end, said first
lateral end of each of said structural member being secured to either said
first upper member or said second upper member;
raising the first and second upper members to a predetermined elevation,
and into a concentric position above a diameter of the lower foundation;
directing the second lateral end of said structural members downwardly
toward the lower foundation, and securing said second lateral ends of said
structural members to said lower foundation; and,
modifying the rotational position of said first upper member relative to
said second upper member, wherein said first upper member is at a position
rotatable offset from its initial relative position.
14. The process of claim 13, wherein after said rotational relative
position change of said first and second upper members, said structural
members overlap adjacent structural members at cross points, further
comprising the step of:
securing said structural members to adjacent structural members at such
cross points.
15. The process of claim 13, wherein said first upper member and said
second upper member are both rotated, the direction of rotation of said
first member being opposite the direction of rotation of said second
member.
16. The process claim 13, wherein after said rotational relative position
change of said first upper member and said second upper member, said first
and second upper members are secured to each other to prevent the members
from assuming their original equilibrium state.
17. A process for creating a dome support structure comprising:
providing an upper member, a plurality of structural members and a lower
foundation;
attaching the plurality of structural members, respectively, adjacent a
first lateral end thereof to the upper member, said structural members
extending radially outwardly at angular intervals from said upper member;
raising said upper member to a predetermined elevation;
connecting pairs of said structural members at substantially a second
lateral end of said structural members, and directing said second lateral
ends of said structural members toward one another;
connecting said pairs of said structural members at a location proximal
said second lateral end of said structural members and directing portions
of said structural members toward one another such that portions of said
structural members overlap adjacent structural members;
connecting overlapping structural members with a fastener; and,
connecting said second lateral ends of said structural members to the lower
foundation.
18. The process of claim 17, wherein the step of attaching the plurality of
structural members to the upper member comprises attaching said structural
members to said upper member at an inclined angle.
19. The process of claim 17, wherein said upper member comprises a first
ring member and a second ring member, and wherein the step of attaching
the plurality of structural members to the upper member comprises
attaching alternating structural members to the first ring member and
second ring member, respectively.
20. The process of claim 17 further comprising the steps of:
attaching a support mechanism to said pair of structural members after said
second lateral ends of said structural members are directed toward one
another.
21. The process of claim 17, further comprising the step of:
grouping the structural members in an upper and a lower array.
22. The process of claim 17, further comprising the step of:
directing the structural members toward one another in a predetermined
order.
23. The process of claims 20, further comprising the step of:
directing the structural members toward one another in a predetermined
order.
24. A column less support structure, comprising:
an upper member;
a lower foundation; and,
a plurality of integral elastically deformed structural members rigidly
fixed to said upper member and said lower foundation, wherein the integral
structural members radially extend at angular intervals from the upper
member, wherein a portion of adjacent integral structural members overlap
a portion of adjacent structural members between the upper member and the
lower foundation, and wherein the upper member of the support structure is
supported by the structural members and is not supported by vertical
supports.
25. The column less support structure of claim 24, wherein said integral
structural members comprising an upper array and a lower array elastically
modified into a lattice formation of cross-overlapping S-shaped members
between said upper member and said lower foundation.
26. The columness support structure of claim 25, wherein said
cross-overlapping S-shaped structural members are joined together at the
cross-overlapping locations, to create a single layer frame dome
structure.
27. A self-supporting dome support structure, comprising:
an upper member;
a lower foundation; and,
a plurality of structural members rigidly fixed to and radially extending
from the upper member in overlapping arrays, the structural members
extending downward and anchored to the lower foundation at an angular
orientation, wherein the structural members of the overlapping arrays are
elastically modified by twisting and bending each structural member into
an S-shaped configuration, wherein after such elastic modification a
portion of adjacent structural members overlap a portion of adjacent
structural members along their length between the upper member and the
lower foundation to form a lattice configuration, and wherein the
overlapping structural members are secured to each other at overlapping
locations.
28. The self-supporting dome support structure of claim 27, wherein the
upper member comprises a hub. |
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Claims |
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Description |
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DESCRIPTION
1. TECHNICAL FIELD
This invention relates generally to a support structure and, more
particularly, to a support structure for a domed building and a method of
making that structure.
2. BACKGROUND OF THE INVENTION
The prior art discloses various configurations for supporting different
kinds of structures. Specifically, U.S. Pat. No. 5,408,793 ("the '793
patent") is directed to a dome structure. As may best be seen in FIG. 10
thereof, the '793 patent discloses a structure having an outer base 44, an
inner base 43, and outer 39 and inner membranes 16, respectively.
Generally, these outer and inner membranes are inflated and are held down
from uplift forces by concrete members anchored to the ground.
Alternatively, the membranes are tailored to a specific shape and are
positioned on the inner or outer bases. FIG. 7 of the '793 patent shows
the wire structure underlying this dome.
U.S. Pat. No. 5,117,852 ("the '852 patent") is directed to a free-standing
structure. As may best be seen in FIG. 2 of the '852 patent, the structure
has a polygonal base. In particular, FIG. 2 shows a pentagonal base. At
each of the points of the pentagon there are two arch members 16. The arch
members are elongated and have two opposite ends, a first end and a second
end. The first end of each of the arch members emanates from the same
point on the pentagon. Each of these arch members 16 whose first end
emanates from this same point crosses over the other arch member. The
second ends of the respective arch members 16, however, are secured to the
pentagon at different points.
U.S. Pat. No. 4,265,259 ("the '259 patent") is directed to a tent and may
best be seen in FIGS. 1 and 2 thereof. The '259 patent discloses a series
of stressed, arcuate rods 11 which surround a convex polyhedra such as a
hemispherical structure.
U.S. Pat. No. 3,922,827 ("the '827 patent") is directed to a hyperbolic
tower structure. As shown in FIG. 1, the '827 patent discloses a tower
structure consisting of a central vertical frame shaft surrounded by an
outer structure in the form of a hyperboloid of revolution composed of two
sets of intersecting straight linear structural elements arranged to
define the hyperboloid. The linear elements are connected at their
intersections to the central shaft by horizontal radial bracing members.
U.S. Pat. No. 3,893,270 ("the '270 patent") is directed to a pressure
vessel comprising a walled body formed of concrete. This concrete walled
body is built upon a wire frame. Each of the wires making up this frame is
prestressed. Further, each of these wires extends continuously throughout
the length of the body within the wall of the body between first and
second anchor locations which are positioned at a same general
longitudinal location. The structure of these wires is best seen in FIG.
2. The '270 patent discloses that the wires are positioned at a same
general longitudinal location along the cylindrical member of the
structure.
U.S. Pat. No. 3,649,401 ("the '401 patent") is directed to a method of
making an ornamental structure for supporting a piece of furniture.
Essentially, the structure of the '401 patent is comprised of a pair of
end plates to which strands are attached. The strands are saturated with a
polyester resin which hardens to provide the structure with rigidity.
U.S. Pat. Nos. 2,753,818 ("the '3818 patent") and 2,670,818 ("the '0818
patent") are directed to structures supporting a hemispherical dome. As
can best be seen from FIGS. 2 and 3 of the '3818 patent and FIGS. 5-6, 10,
and 12-13 of the '0818 patent, these domes are supported by radially
extending ribs 13 and b, respectively. The ribs of the '3818 and '0818
patents do not cross over any of the other ribs thereof.
U.S. Pat. No. 1,976,188 ("the '188 patent") is directed to an arcuate metal
structure serving as a truss. FIGS. 1 and 2 of the '188 patent disclose
that this structure is made of rods or unit-elements 1 that are configured
in a pure arc, i.e., as "parabolic, semi-circular and other convexed
curvatures of substantially continuous nature." (emphasis added) (See '188
patent, page 1, lines 3-6.) One end of each unit element 1 touches the
ground, while the other end of each unit element 1 is secured to the frame
of one of the two arches. (See especially FIG. 1.)
SUMMARY OF THE INVENTION
The support structure of the present invention includes at least one upper
ring member, and more preferably two upper ring members, and a plurality
of structural members in a lattice formation extending downward from and
secured to the upper ring member. The support structure also includes a
lower foundation member having a diameter greater than the diameters of
the upper ring members, and most preferably, the diameter of the lower
foundation member is equal to at least three times the diameter of the
upper ring member or members.
According to one aspect of the present invention the structural members
comprise a plurality of initially straight and elongated structural
members which extend from the upper ring members. Preferably, each of the
elongated structural members have a substantially circular cross section.
Each of the elongated structural members have a first and a second lateral
end. The elongated structural members extend radially outward from the
upper ring members at equal angular intervals thereof. Further, each of
the elongated structural members are secured adjacent their first lateral
ends to the upper ring members. In the embodiment having first and second
upper ring members, an equal number of elongated structural members extend
from and are secured to each of the ring members. As such the elongated
structural members preferably alternate being secured to and extending
from the first ring member and the second ring member, respectively, with
a first structural member extending from the first upper ring, a second
structural member extending from the second upper ring, a third structural
member extending from the first upper ring, a fourth structural member
extending from the second upper ring, and so on. The elongated structural
members are secured adjacent their second lateral ends to the lower
foundation.
According to another aspect of the present invention, the initially
straight, elongated structural members are elastically deformed or
modified. As such the structural members assume a generally S-shaped
lattice configuration between the upper member and the lower foundation.
The S-shaped lattice configuration of the structural members contributes
to the strength of the support structure.
According to another aspect of the present invention, after the structural
members are elastically deformed to form the S-shaped lattice
configuration each of the structural members overlap portions of adjacent
structural members at connection points.
According to another aspect of the present invention, the structural
members are secured to overlapping structural members at the connection
points with fasteners.
According to another aspect of the present invention, at least two methods
for manufacturing or installing the support structure of the present
invention, including variations thereof, are provided.
Other features and advantages of the invention will be apparent from the
following specification taken in conjunction with the following drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
To understand the present invention it will now be described by way of
example, with reference to the accompanying drawings in which:
FIG. 1 is a perspective view of a prototype finished support structure in
accordance with the present invention;
FIG. 2 is a top plan view of the first and second upper ring members with a
plurality of initially straight elongated structural members extending
from the upper ring members;
FIG. 3 is a top plan view of the structure of FIG. 2 after the first and
second upper ring members have been rotated relative to each other and
offset from their original positions;
FIG. 4 is a top plan view of the structure of FIG. 3 after the first and
second upper ring members have been rotated relative to each other and
offset from the end positions of FIG. 3 by an additional angle;
FIG. 5 is a perspective view of the structure of FIG. 4, shown in model
size, after final rotation of the first and second ring members through a
total angle of .gamma. as illustrated in FIG. 4, and including the
attachment of the support structure to the lower foundation and securement
of the overlapping structural members with fasteners;
FIG. 6 is a cross-sectional side elevation view of a portion of the
structure of FIG. 5 taken through lines 6--6 of FIG. 5;
FIG. 7 is a top plan view of an upper portion of the device for rotating
the first and second upper ring members of FIG. 5;
FIG. 8 is a top plan view of a lower portion of the device for rotating the
first and second upper ring members of FIG. 5;
FIG. 9 is a top plan view of the first upper ring member illustrating an
alternative attachment of the structural members;
FIG. 10 is a top plan view of the second upper ring member illustrating an
alternative attachment of the structural members;
FIG. 11 is a top plan view of the first and second upper ring members with
a plurality of initially straight elongated structural members extending
from the upper ring members, and including another means for rotating the
first and second upper ring members relative to each other to offset the
rings from their original positions;
FIG. 12 is a top plan view of a plurality of initially straight elongated
structural members extending from an upper ring member before angular
manipulation of the structural members;
FIG. 13 is a partial side elevation view of the structure of FIG. 12;
FIG. 14 is a top plan view of the structure of FIGS. 12 and 13 after first
manipulation of the structural members from their original positions;
FIG. 15 is a top plan view of the structure of FIGS. 12 and 13 illustrating
a second manipulation of the structural members from their positions as
shown in FIG. 14 to a final position;
FIG. 16 is a top plan view of the support structure of the present
invention following: final manipulation of the support structures as
illustrated in FIG. 15, attachment of the support structure to the lower
foundation, and securing the overlapping structural members with
fasteners; and,
FIG. 17 is a side elevation view of an alternate support member for
connecting the structural members to the lower foundation.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
While this invention is susceptible of embodiment in many different forms,
there is shown in the drawings and will herein be described in detail
preferred embodiments of the invention with the understanding that the
present disclosure is to be considered as an exemplification of the
principles of the invention and is not intended to limit the broad aspect
of the invention to the embodiments illustrated.
Referring now in detail to the Figures and initially to FIG. 1, there is
shown a preferred embodiment of the dome support structure 34 constructed
in accordance with the present invention. FIGS. 2-4 and 9-10 illustrate
various structure and steps in a first process or method for manufacturing
the support structure 34. Additionally, FIGS. 5-8 illustrate various
structure and steps in accordance with manufacturing a "model" of the dome
support structure 34. FIG. 11 illustrates a variation of the first method
for manufacturing the support structure 34. Finally, FIGS. 11-17
illustrate various structure and steps in a second process or method for
manufacturing the support structure.
The support structure 34 illustrated in FIG. 1 is made using a number of
elements. As may be seen in FIG. 1, the structure 34 includes an upper
member 35 which, in the embodiment illustrated in FIG. 1, comprises a
first upper ring member 36 and a second upper ring member 38. These ring
members 36, 38 may be a girder or truss type ring design made of composite
or lightweight metallic material which can withstand high stress, and
which exhibit high stiffness characteristics. These ring members 36, 38
are preferably, but not necessarily, substantially identical in size,
specifically including in their inner and outer diameters. While the upper
member 35 is described as including a first and a second ring member, it
is understood that the upper member 35 may be comprised of a single ring
member. It is further understood that the shape of the member 35,
including the components thereof, does not have to be that of a ring.
Additionally, the shape of the upper member 35 and the lower foundation 42
could be oval, hexagonal, or some other shape. It is important, however,
that the connection points of the structural members to the upper member
and the connection points of the structural members to the lower
foundation be of the same shape, but of different scale. If the connection
points form a shape other than circular, it is preferred that the method
of manufacture of the dome structure for this configuration be under
Method II herein.
A plurality of initially straight and elongated structural members extend
from the upper ring member 35. As illustrated in FIGS. 2-4 there are
thirty-two elongated structural members which are identified as structural
members 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, and 32, and which are
generally secured to one of rings 36, 38. Where the support structure 34
includes a numerically even number of structural members 1-32, as is the
case in the embodiment illustrated in FIGS. 2-4, one structural member is
generally diametrically opposed to a corresponding structural member. For
example, structural member 1 is diametrically opposed to structural member
17; structural member 2 is diametrically opposed to structural member 18;
structural member 3 is diametrically opposed to structural member 19;
structural member 4 is diametrically opposed to structural member 20;
structural member 5 is diametrically opposed to structural member 21; and
so on. In the event that the number of structural members selected was an
odd number, then the structural members would not necessarily be
diametrically opposed.
The structural members 1-32 are generally substantially similar in physical
characteristics, i.e., they are each made of the same material, are each
of a substantially identical diameter and length, etc. . . . In the
preferred embodiment, the structural members 1-32 are also generally
circular. The term "circular" in the context of the structural members
1-32 of this invention is intended to mean that members 1-32 have a
generally circular cross-section. In the case of the circular structural
members 1-32, they may generally have cross sections that are either in
the form of solid rods, hollow tubes, or some other form of a generally
circular cross section. Optionally, however, the structural members 1-32
may have a cross-section that is other than circular. Generally, each of
the structural members 1-32 is made of a high tensile steel.
Alternatively, the structural members 1-32 may be made of a composite
material (carbon-reinforced or other material). As shown in FIGS. 9 and
10, an equal number of these initially straight and elongated structural
members extend from each of upper rings 36 and 38. In this embodiment
wherein two upper rings 36, 38 form the upper member 35, an equal number
of structural members extend from rings 36 and 38 in an alternating
manner. For example, even-numbered members 2, 4, 6, 8, 10, 12, 14, 16, 18,
20, 22, 24, 26, 28, 30, and 32 extend from first upper ring member 36, and
odd-numbered members 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27,
29, and 31 extend from the second upper ring member 38.
Moreover, as is seen in FIG. 2, each of the elongated structural members
1-32 extend radially to and at equal angular intervals (.theta.) from the
upper member 35. The general formula for .theta. in any given structure
having equal angular spacing between structural members is
.theta.=360.degree./.chi., wherein .chi. equals the number of structural
members. Because the embodiment of FIGS. 1-4 includes thirty-two
structural members, .theta. for this particular embodiment is
360.degree./32 or 11.25.degree.. In an embodiment having thirty-six
structural members, .theta. would be 360.degree./36 or 10.degree.. As may
also be seen in FIGS. 9 and 10, when upper member 35 includes a first
upper ring 36 and a second upper ring 38, the structural members 1-32
extend from both the first upper ring 36 and second upper ring 38. In the
preferred embodiment, the structural members alternate extending from the
first and second upper ring members. As such, the angular separation of
the sixteen (16) adjacent structural members on either the first upper
ring 36 or the second upper ring 38 is two times .theta., i.e.,
(2)*(11.25.degree.), or 22.50.degree..
As shown in FIG. 2, each of the elongated structural members 1-32 have a
first lateral end 40 and a second lateral end 41. Generally, the first
lateral end 40 or area adjacent the end thereof is secured to either the
first upper ring member 36 or the second upper ring member 38 of the upper
member 35. Similarly, generally the second lateral end 41 or the area
adjacent the end thereof of each of the elongated structural members 1-32
is secured to a connecting support member on the lower foundation 42.
The lower foundation 42 of the present embodiment, illustrated in FIG. 1,
is generally configured in a circular or ring shape. However, as noted
above with respect to the upper member 35, the lower foundation 42 may
comprise any shape. It is preferable, however, that when completed, the
series of connection points between the second lateral ends of the
structural members 1-32 and the lower foundation 42 forms the shape of a
circle. This lower circle or lower diameter is formed by the series of
connection points between the structural members 1-32 and the lower
foundation 42 and generally has a diameter greater than the diameters of
the first 36 and second upper ring members 38. Similarly, the diameter of
the upper circle or ring is formed by the series of connection points
between the structural members 1-32 and the upper member 35. Most
preferably, the diameter of the lower circle of the foundation 42 is at
least three times the diameter of each of the upper circle of the upper
member 35 or first and second rings 36, 38.
One example of a "model" embodiment of the invention was manufactured by
the inventor and is illustrated in FIG. 5. In this "model" embodiment, the
first upper ring member 36 and second upper ring member 38 have an outer
diameter of nine (9) inches, and an inner diameter of six and one half
(61/2) inches. The height of the support structure 34 from the top of the
first upper ring 36 to the base of the lower foundation 42, was
approximately nine and one-half (91/2) inches. The lower foundation 42 of
this embodiment had a circular ring shape. Its inner diameter was
approximately twenty-two (22") inches, and its outer diameter was
approximately thirty (30") inches. Thus, the outer diameter of the lower
foundation 42 was actually somewhat greater than three times the outer
diameter of the first and second upper ring members 36, 38. Additionally,
in this "model" example the structural members were made of a solid high
tensile steel (S.sub.y =240,000 psi., and E=30,000 ksi.) having a circular
cross-section with a diameter of one-sixteenth (1/16") of an inch. The
structural members 1-32 in this embodiment were obtained from the O'Hare
Spring Company, Des Plaines, Ill. 60016.
As explained as being preferred above, in the "model" example the
elongated, circular structural members 1-32 are initially straight when
extending from the first and second ring members 36,38. Ultimately,
however, each of these initially straight, elongated- circular, structural
members 1-32 are elastically modified to attain a generally S-shaped
configuration as shown in FIG. 5. This generally S-shaped configuration
and the resulting lattice configuration that is formed contributes to
phenomenal strength for the support structure 34, permitting the support
structure 34 to bear very high loads. It is believed that the support
structure 34 of the present invention can effectively withstand tremendous
forces applied to the top or to the side of the dome support 34.
Specifically, it is believed that the dome structure 34, due to its unique
design methodology, exhibits a very high stiffness to weight ratio which
is believed to be superior to existing dome structures.
While it is conceivable that the support structure 34 of the present
invention can be made in a variety of different ways, two such methods for
creating the identified support structure 34 in accordance with the
present invention will be described below in detail. The first method is
described by reference to FIGS. 2-4 and 9-10. Additionally, two subsets of
the first embodiment are shown in FIGS. 5-8 and FIG. 11, respectively. The
second method is described by reference to FIGS. 12-16.
Method I:
The basic concept of the method employed in the first method is to rotate
the two upper ring members 36,38 with respect to one another. Relative
rotation of the first and second rings members 36,38 with the structural
members 1-32 connected thereto, provides for elastically deforming the
structural members 1-32 to form the lattice configuration shown in FIG. 1.
In this method the sixteen even numbered structural members
2,4,6,8,10,12,14,16,18,20, 22,24,26,28,30, and 32 are connected to the
lower surface of the first upper ring member 36 as shown in FIGS. 1, 6 and
9. This first plurality of structural members could be connected to either
the upper or lower surface or portion of the first upper ring member.
Similarly, the odd sixteen numbered structural members
1,3,5,7,9,11,13,15,17,19,21,23,25,27,29, and 31 are connected to the upper
surface of the second upper ring member 38 as shown in FIGS. 1, 6 and 10.
Like the first plurality of structural members connected to the first
upper ring member, the second plurality of structural members connected to
the second upper ring member could be connected to either the upper or
lower surface or portion thereof. The exact vertical location of the
structural members on the specific ring members is not critically
important. What is important is that the structural members connected to
the first and second upper ring members be vertically offset (as shown in
FIG. 6) to allow a minimum clearance for the structural members to overlap
each other during rotation thereof.
As shown in FIG. 2, the first upper ring 36 is placed in an initial
relative position concentrically over the second upper ring member 38, and
is rotatably connected to the second upper ring member 38. Alternately,
the first upper ring member 36 may be placed concentrically over and
secured to the second upper ring member 38 prior to the securement of the
structural members | | |
