CA1287725C - Inflatable wall structure - Google Patents

Abstract

Abstract of the Disclosure A roof formed from a self-supporting inflatable structure including a polyhedron frame made from tension cables interconnected and joining at nodes and an envelope surrounding the frame. Anchoring skirts extend from each node lines to predetermined lines on the panels forming the envelope.
The polyhedron frame is such size as to provide an arch shaped roof covering an area to be covered, and when the envelope is inflated, and sufficient internal air pressure is therein maintained, all of the tension cables are under tension and the overall structure becomes rigid, stable and capable of resisting deformation caused by external forces applied to it.

Description

Tlle presellt invention relates to a selr-supporting illflatable ~clual wall structure and more speci-Eically oE a type utiliæecl ~or forming rooE structures ancl other Lightweight large span selE-supporting open structures.
Numerous attempts have been made to provide a pneumatic clual wall roof or cover made of lightweight Eabric or synthetic material. One type includes a cel]ular construction as shown in U. S. Patents 3,247,627, Bird, 1966;
3.030,640, Gosman, 1962; 3,779,847, Turner, 1973; 511,472, Sumovski, 1893; 2,837,101, Bary, 1958; 3,256,649, Webb, 1966;
3,292,338, MacClarence et al, 1966; 4,186,530, Fraioli, 1980;
3,973,363, Lal'orte et al, 1976 and 3,227,169, Fischer, 1966.
Another form of dual wall inflatable structure is the type shown in U. S. Patent 4,004,38Q, Kwake. 1977, in whicll two membranes form the inflatable structure and tension rods or tension cables extend between anchor points on the membranes. Examples of this type of structure are shown in U. S. Patents 3,123,085, Desmarteau, 1964; 2,253,019, Phane, 1956; 2,743,510, Mauney et al, 1956; 2,698,020, Phane, 1954; 2,657,716, Ford, 1953; 2,636,457, Finlay et al, 1953;

2,016,054, Sentell, 1935; and 3,277~614, Marié, 1966.
The Marié patent, for instance, shows a framework oE cables Eorming a beam or girder surrounded by a cover, the cover including prisoner cables attached to nodes formed from connecting cables res~lting Erom the triangular structure of the framework. The resulting structure shown in Figure 7 and 8, is a complex unidirectional inflated girger or beam.

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It is an Elim oE the l~resent invention to provide an in~cltable struc~ure whicll is lightweight yet selE--supl)ortillg and lla~ing a struct-lral in~egrity which is s~l~ficiellt tn provide a cover or roof spanning a large area. lt i5 contemp1ated that an inflatable structure o~
tlle type described can span a large area without interme-diate supports if the structure is ~or instance, an arch having a somewhat parabolic curve and resting only on its edges. The span can be far greater than that attained presently by conventional single membrane air supported buildings using similar type of eanvas material and Far lighter than any type of construction.
A cons-truction in accordance with the present invention comprises an inflatable double wall pneuma-tic structure including a polyhedron eable frame assembly~ The frame eomprises a pair of spaeed-apar-t grids with eaeh grid made up of cable tension elements in quadrilateral patterns with each tension element eonneeted to interseeting tension elements at nodes in the plane of the respee-tive grid.
Cable tension elements extend be-tween the grids and are con-nected -to corresponding nodes in the respeetive grids.
The grids de~ine the upper and lower surfaees of the eable frame, and an air impervious flexible elosed envelope totally eneloses the eable frame. The walls of the envelope inelude spaeed-apart anehor means conneeted to eorresponding nodes on the respeetive grids of the eable frame such that when the envelope is inElated and subjec-t to pneumatic pressure, the tension elements forming the cable frame will be under tension eausing the cable frame to assume its intended shape.

~ construction in accordance with the presellt invelltioll comprises a pneumatic self-supportin~ structure lnGluding an inner cable frame and an ou-ter imperv:Lous envelope. The cable frame,made up of flexible linear tension elements such as many structurally suitable types oE cables or woven belts, mainly consists of a pair of facing and spaced apart grids with each grid being Lormed by the perpendicular intersection of two series of parallel and regularly spaced cables interconnected at nodes, and, flexible linear tension elements or cables extending from one grid to the other and fixed at their both ends to each pair oE corresponding facing nodes. The plurality of the interconnected cable elements are adapted to form a polyhedron frame, when fully extended, and the envelope surrounds the frame. The envelope comprises flexible substantially impervious panels extending about the perimeter and the outer surfaces of the cable Erame grids and joined together to ¢ontain the cable ~rame therein. An-chor means are provided on the inslde face of the envelope panels to Eirmly tie each nodes of the polyhedron cable frame to its surrounding envelope whereby when -the so-Eormed inflatable envelope is inflated, the polyhedron frame will be Eully erected and each cable element forming the erected polyhedron cable frame will be ~Inder tension.

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In a more sl-eciric embodiment oE tlle preserlt :invellLioll, tllere is provided .1 uneumatic sel.l~-supl)ortill roo~ structure aclapted ~o cover a predeterlllillecl aurface, tlle rooE struc~ure comprisin~ an arcll shaped pneumaticaLly inELated envelope enclosing a similarly sllaped polyhedron cable Erame and extending laterally across tlle area to be covered and longitudinally thereof. The envelope and cable frame asselllbly is essentially composed of a plurality oE
identical adjaccnt sections connected side by side Witll each section extending in tlle lateral direction between parallel support structures which are longitudinally bordering the area to be covered. Eacil section includes a top and bottom strip oE impermeable ~aterial, ea~h strip having its parallel longitudinal edges provided Witll continuous connecting means adapted to connect adjacent strips at respective seams to form top and bottom envelope panels respectively. Eacll section includes also, in between ~he top and bottom strips, a series of somewhat rectahedron shape cable sub-frames connected end to end, mutually sllaring the connecting common faces, each such sub-frames made up oE flexible cable elements deEining the edges of the rectahedron thus Eormed and nodes defining tlle junction of tlle cable edge elemenLs. A tension skirt extends continuously fro and along the inward side of the seams connecting two adjacent se~tion strips an~ is fitted with regularly spaced anchoring means to be an~hored to an arch line of successive nodes respectively on top and bottom side oE
the cable Erame section. Side strips and end covers complete tlle envelope and are connected along the edges oE tile strip assemblies oE tlle top and bottom panels. The tension skirt nnd l)a~lel s~ction assem~lies ancl the rLexil)le cable eLements are so dillletlsiotled that wllen tlle envelope allcl cabLe Erallle 1SSelllb~y i9 completed an-l inElated to maintaill a interncll pl-essure, all of the cable elements are uncler tension, thereby pLoviding a self-supporting arch-shapecl rooE.

When the envelope is inflated and the cable elements are under tension, the structure becomes quite rigid, and when the flexible cable el~ments ~orming the polyhedron cable frame are properly selected and an adequate number and location oE diagonal cable struts are provided and fixed to their proper pair of nodes, the arch-shaped sectionsare like rigid arched trusses.
The span of a roof Eormed by these adjacent arch sections structurally connected to one another successively may be quite large ancl certainly the span can cover, without any intermediate supports, an area greater than any known single or multiple inflatable membrane structures built today. The structure of this invention can be utili~ed to cover stacliums or tennis courts, etc. The preferrecl curvature oE the arches is parabolic or catenary. The structure can be adapted to various loads such as in northern climates where snow weight must be supportecl during winter months. If a greater load must be carriecl the air pressure within the envelope can be increased to meet the requi-red loacls. It is evident t6at by increasing the air pressure within the envelope, the tension in the cable elements of the structure will be increased and so will its rigidity and load bearing capacity.

77~5 llavin~ thus generally described the nature oE
the inventioll, reEerence wiLl now be made to the accompilllying drawings, StlOWing by way oE illustratlorl, a preferred embodiment theroE, and in which:

Figure 1 is a perspective view of an arch-shaped roof embodying the present invention;
Figure 2 is an end elevation of the roof shown in Figure l;
Figure 3 is a fragmentary enlarged perspective view showing details of the present lnventlon;
Figure 4 is a fragmentary view, partly in cross-section, showing the side supports;
Figure 5 is a vertical cross-section taken along line 5-5 of Figure 4;
Figure 6 is an enlarged plan view of ~ detail of the present invention;
Figure 7 is a vertical cross-section taken along line 7-7 of Figure 6; and ~ Figure 8 which is on the same sheet of drawings as Figure 3, is an enlarged perspective view of another embodiment of a detail as shown in Fi~ure 3.

Referring now to the drawings and particularly to Figures 1 and 2 of the drawings, there is shown a large roof structure 10 including an enve:Lope 11, and including a number of side-by-side arch sections 12, identified 12a, 12b, 12c,...12n. The complete inflated roof 10 is supported at each side edge by support members 14. The roof is meant ~.~87~:~5 to cover an area ~. Tlle rooE 10 can be contelllpLated ~IS
being made up oE a ~op impermeable panel of Elexible material 16 and a bottom panel 18.
The complete rooE envelope 11 can be better described by reEerring to the individual identical sections 12a, 12b, 12c,...12n. The sections are joined together to form the complete impermeable air-tight envelope with an internal cahle ramework 20 which is made up of side-by-side rectahedron shape sub-frames connected in end-to-end series in each section 12a, 12b, 12c,... 12n.

Typical sections 12b and 12c are illustrated in Figure 3. Each section 12b and 12c includes an upper strip 22 and a lower strip 24. Adjacent strips 22, Eor instance, are connected along their respective edges by means oE threads, in the present embodiment, to form a seam 26. Similarly, the strips 24 are connected along their edges to form seams 28. Each strip is made oE a suitable material such as vinyl reinforced with nylon3 Kevlar or Dacron or other ~uitably strong woven material.
~ach strip 22 and 24 extends Erom one side oE the envelope 11 to the other, that is, the complete length of a section 12b and 12c, or from one support member 14 to the other.
Selected str.ips 22 and 24 could be cu-t longitudinally into two parts and provided with an inter-locking Eastener system as shown in Figur.es 6 and 7, which would divide the panels into modules of several sections In this case, the cut edges of the strips 22 and 24 may be folded over and sewn and spaced-apart cuts making loops 23 may be provided in which dowels 21 are fixed and adapted to interlock as shown in Figures 6 and 7. Each dowel may ~t7~2~

have a rounclecl end 25 and a complementary female ~locket portiol~ 27 aclapted to receive ttle rounded end 25 oE nn adjacellt dowel 21. The tension on tha strip material rorces the interlo~king the clowels an~l provides for an air-tight seam.
Referring back to Figure 3, each of the seams 26 and 28 is further provicled with an anchoring skirt 30 and 32 respectively. These anclloring skirts are of strong woven material and include a belting or overlapped webbing 33 to reinforce the edges thereof. In the present embodiment, the anchoring skirts 30 and 32 are scalloped to form gradual arch-sllaped segments segments as illustrated with an annular reinforcing eyelet ring defining an anchor position opening 34 at tlle apex of each scallop.

In Figure 3, a complete rectahedron shape frame portion or sub-frame 36 is illustrated having respective nodes 38, 40, 42, 44, 46, 48, 50 and 52. These nodes 38..i.52 Eorm the respective corners oE the rectahedron sub-frame 36. These nodes may include a single annular ring 37 or a pair of rings 37 and 39 welded or otherwise connected together 6uch that the center of eacll ring coincides and the rings are in 90 planes as shown in Figure 8. Lengths of tension cable extend between each node 38...52 alld form the edges of the hectatledron sub-frame 36. For instance, spanwise cables 54, 56, 58, 60, which are running along the direction of section 12c, are connected respectively to their designated nodes by means of conventional hardware pieces 54a, 72a, etc.
These hardware pieces may be any other ~2~37~

goocl state oE tlle art device Eor sucll application.
Vertical cabLe elements 62, 64, 66 and 68 are aLso con~ected to their respective nocles. ~To name each respective node would bur(len the present description, but the Location oE
each cable element is identi~ied in the drawings.) Lengthwise of the overall structure, extending tension cables 68, 70, 72 and 74 are also illustrated extending between respective corner nodes while diagonal struts 76 (also tension cables) may be provided at diEferent locations to reillforce selected rectahedron sub-frames. These diagonal cable struts 76 are not essential and are used generally to reinforce certain regions of the overall polyhedron cable rame structure Eor good design practice to further resist to deformations due to outside and perhaps assymetrical loading such as wind or snow.
As is evident from Figure 3, adjacent side-by-side rectahedron sub-frames are connected and, in fact, spanwise cable elements 54 and ;8 are common to adjacent sub-frames 36 of adjacent sections 12b and 12c. The rectahedron sub-Erames are connected lengthwise end to end as well withina unit section 12 and cable elements 68 and 70 are common to two successive hectahedron sub-frames 36. The resulting cable framework is a three dimensional bridge structure having an overall arch shape. Each node 38, 40, 42, 44, 46, 48, 50, and 52 is connected to a respective anchor position 34 on the anchoring skirts 30 and 32 respectively oE each seam 26 or 28. Thus, when the envelope 11 is inflated,the top strips 22 tend to pull apart from bottom 377~S

strips 24 but are held in place by the pulling o~ th~ skirt.s 30 and 32 whicll in turn, through the anchor rings 34, pull on the nodes of the rectahedron sub~frame inducing tensiorl in the vertical cable elements 62, 64~ 66, 68, proporLionaLy in~ernal air pressure and area of cross-section covered by one such cable element. Pneumatic air pressure acting in all directions, tension will also be similarly induced in the spanwise cables as well as in the lengthwise cables.
ReEerence will now be made to Figures 4 and 5 which show the end conEiguration of each section. Each o~
the strips 22 and 24 are pleated near the end corners at 80 and 82 and sewn so as to give the strip an arch shape at its ends and is sewn directly to both end panels 84, whic}l extend along the length sides of the top and bottom panels 16 and 18 by sewing to the top strips 22 and the bottom strips 24 respectively. The last rectahedron sub-frames 36 of the cable framework are attached to end skirts 86 and 88 which extend along the connection seam between top and bottom panels 16 and 18 and end panels 84 respectiveLy.
The end panels 84 include loops 90 and 92 which are adapted to receive the tubular ramp members 95 of side supports 14.
Tlle side support includes a succession of tubular frame supports 94 and vertical stabilizer supports 96. The ends of the supports 94 and 96 must be anchored solidly to the ground to counteract any upward or lateral forces exerted thereon by the envelope ll as a result o~ wind lift.
Furthermore, a large si~e tension skirt 98 may also be ~2~

proviclecl to structur<l:Lly contlect the supports 94 to Lhe sicle eclges oE the pneumatic structure envelope. A suitnble bracing lO0 is also provided between support members 94 ancl rallll) members 95 as well as extending flexible cabl cross bracing 102 between adjacent support frames 94.
The en~ sections 12a an~ 12n oE the envelope ll are closed by end caps , also made of mat~rial, by sewing its edge to the outside edges of strips 22 and 24 by means oE a seam similar to 26 and 23 and also bearing skirts similar to 30 and 32 to anchor to the outermost upper and lower nodes of the cable framework respectively to complete the air tight envelope ll.

Claims (16)

1. An inflatable double wall pneumatic structure including a polyhedron cable frame assembly, said frame comprising:
a pair of spaced apart grids with each grid made up of cable tension elements in quadrilateral patterns with each tension element connected to intersecting tension elements at nodes in the plane of the respective grid; cable tension elements extending between the grids and connected to corres-ponding nodes in the respective grids, the grids defining the upper and lower surface of the cable frame and an air impervious flexible closed envelope totally enclosing the cable frame, the walls of the envelope including spaced apart anchor means connected to corresponding nodes on the respective grids of the cable frame such that when the envelope is inflated and subject to pneumatic pressure the tension elements forming the cable frame will be under tension causing the cable frame to assume its intended shape.

2. A structure as defined in Claim 1, where the cable frame and envelope will assume a parabolic arch shape composed of a large number of adjacent individual rectahedron shape sub-frames sharing common tension elements at their sides and common nodes at their corners, and the walls of the envelope are slightly oversized and the envelope is restricted in its expansion by the anchor means attaching spaced apart points of the envelope to respective nodes on the cable frame.

3. An inflatable structure as defined in Claim 1, wherein the tension elements are in the form of flexible cables.

4. An inflatable structure as defined in Claim 2, wherein the impervious double wall envelope is made up of strips of impervious woven material connected edge to edge with adjacent strips and each strip extending in the arch direction and corresponding in number to the number of rectahedron assemblies, the edge to edge connection formed by seams and including continuous skirts at the seam extending inwardly of the envelope to which are attached the envelope anchoring means, its said strips forming arches across the polyhedron assemblies from seam to seam.

5. An inflatable structure as defined in Claim 1, wherein tension elements extend directly from a node in one grid to a corresponding node in another grid and diagonal tension members extend from one node in one grid to non corresponding nodes in the other grid.

6. An inflatable structure as defined in Claim 5, wherein all of the tension members from one node to another are individual separate tension members.

7. An inflatable structure as defined in Claim 5, wherein the tension members in the plane of the respective grids extending in a predetermined direction are continuous tension elements intercepted by other tension elements at respective nodes.

8. An inflated structure as defined in Claim 1, wherein the nodes of one grid are connected to the nodes of the other grid by diagonal tension elements extending from alternate nodes.

9. An inflatable double wall pneumatic structure including a polyhedron cable frame assembly, said frame comprising a pair of grids in spaced-apart respective planes, each grid being made up of first cable tension elements extending in one direction and second intersecting cable members extending in a direction transverse to the direction of the first cable members to form quadrilateral patterns, each first cable element connected to intersecting second cable tension elements at nodes in the plane of each said grid; third cable tension elements extending between the planes of the respective grids and connected to correspond-ing nodes in the said grids; the grids defining upper and lower surfaces of said cable frame and an air impervious flexible closed envelope totally enclosing said cable frame, said envelope including top and bottom panels including spaced-apart anchor means connected to corresponding nodes on the grids in the respective planes of the cable frame such that when the envelope is inflated and subject to pneu-matic pressure, the first, second and third tension elements forming said cable frame will be under tension causing the cable frame to assume its intended shape.

10. A structure as defined in claim 9, where the cable frame and envelope will assume a parabolic arch shape com-posed of a large number of adjacent individual rectahedron shape sub-frame sharing common third cable tension elements at their sides and common nodes; the envelope is slightly oversized and is restricted in its expansion by the anchor means attaching spaced-apart points on the top and bottom panels of the envelope to respective nodes on the cable frame.

11. An inflatable structure as defined in claim 9, wherein the first, second and third cable tension elements are flexible cables.

12. An inflatable structure as defined in claim 10, wherein the envelope is made up of strips of air impervious woven material connected edge to edge with adjacent strips, each strip extends in the longitudinal direction of the sub-frame with one strip corresponding to each upper and lower surface of the sub-frames, the edge to edge connection formed by seams, a continuous skirt at each seam extending inwardly of the envelope to which are attached said anchor means, said strips forming arches across the sub-frames from seam to seam.

13. An inflatable structure as defined in claim 9, wherein said third cable tension elements extend directly from a node in one grid to a corresponding node in another grid and diagonal third cable tension elements extend from one node in one grid to non-corresponding nodes in the other grid.

14. An inflatable structure as defined in claim 13, wherein all of the first, second and third cable elements from one node to another are individual separate cable tension members.

15. An inflatable structure as defined in claim 13, wherein the first tension members in the plane of each respective grids extending in a predetermined direction are continuous tension elements intercepted by second tension elements at respective nodes.

16. An inflated structure as defined in claim 9, wherein the nodes of one grid are connected to the nodes of the other grid by diagonal third tension elements extending from alternate nodes.