US3240217A

US3240217A - Structural assembly

Info

Publication number: US3240217A
Application number: US322350A
Authority: US
Inventors: Walter W Bird; George F Reitmeier
Original assignee: Birdair Structures Inc
Current assignee: Birdair Structures Inc
Priority date: 1963-11-08
Filing date: 1963-11-08
Publication date: 1966-03-15
Anticipated expiration: 1983-03-15

Description

March 15, 1966 w. w. BIRD ETAL STRUCTURAL ASSEMBLY 3 Sheets-Sheet 1 Filed Nov.

INVENTOR. WALTER W. BIRD GEORGE F. REITMEIER ATTORNEYS March 15, 1966 w. w. BIRD ETAL STRUCTURAL ASSEMBLY 3 Sheets-Sheet 2.

Filed Nov.

INVENTOR. WALTER W BIRD GEORGE E REITMEIER A. TTORNEYS March 15, 1966 w, w, BlRD ETAL STRUCTURAL ASSEMBLY 3 Sheets-Sheet 3 Filed Nov.

INVENTOR. WALTER W. BIRD GEORGE F. REITMElER WEN A T TORNEYS United States Patent 3,249,217 STRUCTURAL ASSEMBLY Walter W. Bird, Williamsvilie, and George F. Reitmeier, East Aurora, N.Y., assignors to Birdair Structures, Iuc., Bnifalo, N.Y.

Filed Nov. 8, 1963, Ser. No. 322,350 9 Claims. (Cl. 135-3) This invention relates to structural members generally and pertains more particularly to a novel type of beam; particularly, although not necessarily restricted to, a beam of the type used in combination with an air-inflated fabric or like envelope in a building structure.

In its broadest sense, the present invention relates to a structural beam having a relatively stiff compression flange, a flexible tension flange disposed in spaced, generally parallel relation therewith, and flexible web means joining the compression and tension flange members; the compression flange member being deformed and held in such deformed condition by the tension flange member so that both the tension flange and the web means are pre-tensioned. In this manner, a maximum of beam stiffness may be accomplished with great economy of material.

More particularly, the present invent-ion deals with a composite beam assembly which is so constructed as to be highly directional in its load-sustaining characteristics to thereby effect both a great saving of weight and the capability of being compactly stored. A beam assembly according to this invention, when used as a load-sustaining component of a building structure in which other of the building components lend lateral stability to the beam, is outstanding in its light weight character, ease of assembly and disassembly and compactness when stored. Therefore, this invention envisages a novel beam assembly per se as well as such an assembly in combination with means imparting lateral stability thereto. It is therefore an object of the present invention to provide a loadsustaining beam which is at once of lightweight construction, capable of storage with a minimum of space and yet possesses a high degree of rigidity in comparison to its over-all weight.

Tensioned fabric building structures and particularly air-inflated structures are becoming increasingly more popular since building of structures such as these possess certain inherent advantages not enjoyed by other types of structures. For example, recent developments have made possible the utilization of relatively lightweight lfabrics providing an envelope which is inflated under relatively low pressure which lend a substantial degree of rigidity to the envelope due to the pressure-induced tension in the envelope or fabric so as to adapt the same for use as a quickly erected building unit. Such types of structures have, for example, adapted themselves for military purposes where a quickly erected and highly mobile type of structural assembly is desired. One disadvantage of such air-inflated structures is that they constantly require the presence of internal air pressure in order to remain erect. This poses no special problem insofar as sealing is concerned, but it does require the use of air locks in conjunction with any entrance to the building so as to avoid excessive loss of pressure during use of the entrance. Moreover, this problem is grossly magnified in installations requiring large entrance openings, the air lock requirements for a hangar, for example, attaining staggering proportions. Consequently, it is of primary interest in conjunction with this invention to provide a beam or structural member as aforesaid, which is characterized by its light weight, ease of assembly and disassembly and compactness in storage, so as to lend itself particularly, though not necessarily, to use in conjunction with airinilated structures. -In this fashion, an air-inflated envelope, reinforced with the structural members according to this invention, can be made so as to be self-sustaining without the use of internal air pressure, whereby the need for air locks is obviated. Ancillary to this object, and also of primary concern in connection with this invention, is the provision of an improved form of air-inflated structure having an air-inflated and tensioned envelope auxiliarly supported by beam members as aforesaid in which the envelope imparts lateral stability to the beam members while the beam members permit the building to remain erect even in the absence of internal pressure. In this fashion, the building may with impunity be fitted with large access means and, when closed, the building may be operated at minimum internal pressure under conditions of low weather loading and at increased pressures s weather loads increase.

Another object of this invention is to provide a beam structure which is of lightweight construction and which is formed of a plurality of individual sections readily joined together and wherein each one of the sections is so constructed as to permit the same to occupy a minimum of space for storage purposes, thereby materially simplifying logistical problems.

Still another object of this invention resides in the provision of a beam construction consisting essentially of a lightweight metallic flange having in association therewith a flexible tension member joined to the flange through the medium of a flexible web member so that when stored, the flexible web member and the tension member can be collapsed to occupy, with the metal flange, a minimum of space.

A further object of the present invention is to provide a structural beam in which the compression component thereof is formed of a metallic rigid member, wherein the tension portion thereof is formed of a flexible element such as a cable or the like joined to the ends of the compression components, deforming the same to pretension the tension element, and wherein the compres sion and tension components are joined along their lengths by a flexible sheet of material such as fabric or cables capable of distributing shear loads between the upper and lower elements of the beam and which also receives pretension by virtue of the deformation of the compression component.

It is still another object of this invention to provide a novel beam assembly which incorporates a plurality of individual sections to be joined together, each of which includes a rigid compression flange component and flexible web and tension components, all so related that when the sections are operatively joined, the bending stiffness of the compression flange components imparts tension to the tension components and thereby places the Web components under tension throughout.

Other objects and advantages of the invention will appear from the description 'hereinbelow and the accompanying drawings wherein:

FIG. 1 is a perspective view showing a tensioned-fabric structure having associated therewith several of the composite beams according to the present invention;

FIG. 2 is an elevational view showing an arched beam constructed in accordance with this invention and illustrating the sectional characteristic thereof;

FIG. 3 is an enlarged transverse section taken through a beam according to the present invention and showing its manner of construction;

'FIG. 4 is an enlarged elevational view showing a portion of a composite 'beamconstructed in accordance with this invention and illustrating the same in the vicinity of the joint between adjacent components;

FIG. 5 is a plan view of the assembly as is shown in FIG. 4, portions thereof being broken away and also showing the related fabric structure or envelope in association therewith;

FIG. 6 is a longitudinal section taken through a structure such as shown. in FIG. 1, illustrating adjacent beams and the manner in which they are joined by the tensioned flexible envelope;

FIG. 7 is a vertical section taken substantially along the plane of section line 77 in FIG. 4 and illustrating details of the beam construction in the vicinity of the joint;

FIG. 8 is a view similar to FIG. 7 but taken along the plane of section line 8-8 in FIG. 4 illustrating one of the locating pins of the joint mechanism;

FIG. 9 is a view similar to FIGS. 7 and 8 but taken along the plane of section line 99 in FIG. 4 illustrating one of the connecting members for securing the joint;

FIG. 10 is a vertical section taken longitudinally of the beam and illustrating one of the securing devices for the locking strips thereof;

FIG. 11 is a plan view of the assembly shown in FIG. 10;

FIG. 12 is an enlarged elevational view. showing a portion of one end of a beam according to the present invention;

FIG. 13 is an elevational view showing a portion of a modified arch construction;

FIG. 14 is an enlarged sectional view taken substantially along the plane of section line 14- 14 in FIG. 13 showing details of the modified beam;

FIG. 15 is an enlarged section taken along the plane of section line 15-15 in FIG. 13 showing adjacent compresion components of the beam of the arch detachably secured together;

FIG. 16 is a section through a beam according to the modification of FIGS. 13 and. 14 but showing a modified manner of envelope attachment;

FIG. 17 is similar to FIG. 16 but showing a still further modification of envelope attachment; and

FIG. 18 is an elevational view showing a portion of an air-inflated structure utilizing the principles of this invention.

Referring at this time more particularly to FIG. 1, the assembly shown therein is a tensioned-fabric building structure 10 in which adjacent panels of

flexible material

12, 14, 16 and 18 are joined together in edge-to-edge relationship by means of a plurality of structural beams or

arches

20, 22, 24, and there also being end arch members 26 and 2-8. The particular structure shown also employs end wall members of which one can be seen as at 30 in FIG. 1 which is joined to the corresponding end arch or beam member 26. The intermediate arches or

beams

20, 22 and 24 are characterized by the fact that they are capable of sustaining loads substantially only in the plane of these members. That is to say, the beams are highly directional in their load carrying characteristics. Therefore, the structure or means with which the beams are associated must be such as to lend lateral stability thereto and it is for this reason that as for example in FIG. 1,

the

panels

12, 14, 16 and 18 must be tensioned in order to stabilize the beams as aforesaid. In this particular type of construction the manner in which the panels are tensioned is by the guy wires 32 and 34 attached to the end beams 26 and 28 and imparting pull in opposite directions to thereby tension the

fabric panels

14, 16, and 18 and stabilize the beams in the direction of the plane of these panels. It will be apreciated that the guy wires 32 and 34 are illustrated purely schematically in FIG. 1 whereas in actual practice, either a great many more guy wires would be needed to distribute their tensioning force more or less evenly along the respective beams 26 and 28, or the end members 26 and 28 may be constructed to possess the requisite degree of lateral stiffness necessary to operate properly with relatively few guy Wires, the result desired being to achieve a substantially uniform tensioning in the

panels

12, 14, 16 and 18.

As has been mentioned heretofore, the beams or arches acording to this invention are readily adapted for use with air-inflated structures wherein the internal pressure is such as to impart tension in the fabric or envelope so that the guy wires need not always be used, depending upon the particular type of tension fabric structure with which they are associated. The specific beam 36 illustrated in FIG. 2 comprises a pair of end components 38 and 40 of similar construction and a plurality of similarly formed

intermediate components

42, 44, 46, 48, 50 and 52. Initially, these several components are separate and are provided with means hereinafter described permitting the same to be readily attached and detached as required so that the beam as in FIG. 2 may be constructed or may be disassembled into its several component parts each of which occupies relatively little space and is consequently characterized by the ability to be stored and transported relatively easily.

Still referring to FIG. 2, the essential characteristics of the beam shown therein is that it comprises a compression portion as at 54 on the outer side thereof and a tension portion as at 56 at the inner side thereof which compression and tension portions are joined by a flexible sheet of material or web which may take the form of sheets of fabric, for example. The compresion portion is relatively stifi and of greater length than the tension portion so that when the opposite end portions of the compression portion are joined by the tension portion, the tension portion is pre-tensioned. Also, this deformation pre-tensions the web means; the result being a very rigid beam. The specific details of these portions of the beam are shown more particularly in FIG. 3. In this latter figure, the compression portion of the beam will be seen to consist of a pair of generally 'L-shaped members 58 and 60 joined in back-to-back relationship as shown by means of suitable fastening members such as the bolts 62. The two elements 58 and 60 thus present oppositely extending lateral legs 64 and 66 which in the particular construction as is shown terminate along their outer edges in the stiffening beads 68 and 70. The vertical legs 72 and 74 are provided with horn-like

upper edges

76 and 78 whose surfaces are arcuated as shown and spaced apart for purposes which are presently apparent. The two members 58 and 60 are provided with corresponding grooves which present a slot between these members which opens downwardly and is enlarged interior-ily thereof to receive the upper edge of the web assembly 80. This web assembly 80 is arranged on the bias so that the load supporting element can transmit shear loads between flange elements 58 and 60 and the tension element 86 as diagonal tension, or must otherwise be constructed to carry shear loads. The web has its upper edge folded over upon itself as shown and bonded therewith-in is a circular bead element 82 and surrounding the same is a connecting strip 84, all of which is disposed in the aforementioned slot and the bead 82 is so dimensioned as to retain the upper edge of the web 80 within the slot when the two angular members 58 and 60 are joined together as is shown in FIG. 3. Thus, it will be readily apparent that the webs 80 are readily and easily joined to their associated compression components of the beam.

The lower edge of each web assembly 80 is also folded back upon itself and suitably secured to provide a loop within which a length of cable 86 is securely bonded, the cable 86 representing the tension portion of the beam as is indicated by reference character 56 in FIG. 2. Thus, it will be appreciated that each of the components 42-52 is of similar form, each having a predetermined finite length with the opposite ends of the compression component having means associated therewith for quickly and easily connecting and disconnecting the same to a corre sponding end of a next adjacent component and with the cable elements 86 likewise being provided with opposite end connection means so that when the beam is erected as is shown in FIG. 2, all of the compression components are rigidly interconnected to form a continuous structure from one end of the beam to the other end so that the cable elements 86 are likewise so joined. Initially, each section is straight or substantially so and the arch form thereof is achieved by bowing the beam so that the tension components 86 may be joined and placed under tension by relaxation of the externally applied bowing force. Simultaneously, the flexible web 80 which joins the tension and compression portions of the beam is placed under tension.

In FIG. 6, a pair of adjacent beams 90 and 92 are shown, the same being interconnected by means of the envelope panel 94 whose opposite side edges are provided with

bead elements

96 and 98 disposed within the pockets formed between the

horn portions

76 and 78 previously mentioned, there being locking strips 100 and 102 also received in such pockets serving to retain the beaded edges of the panel therewithin as will be readily apparent. The locking strips 100 and 102 cooperate with the beaded edges 104 and 106 of next adjacent panels 198 and 189 and the tensional characteristics of the beaded edges and the locking strips is such as to effect retention of such beaded edges within the pocket defined between the

horns

76 and 78 as will be readily appreciated.

As can be seen more clearly in FIGS. and 11, it will be appreciated that the locking strips such as those indicated at 112 and 114 in these figures are of predetermined len th so that a series of such locking strips are used with each beam. At selected points on the components formiug the composite beam, locking tab members 116 are provided which as is shown in FIG. 10 are generally of T-shaped configuration having a stem 118 pivotally mounted as at 120 between the angle elements 58 and 60, a suitable pocket 122 being formed between such members 58 and 66 to accommodate the tabs 116. The opposite ends of each of the locking strips are provided with angularly upwardly extending nose portions 124 and 126 which are retained beneath the cross bar of the locking tab 116 substantially as is shown. The locking strips are inserted sequentially and the locking tabs 116, when appropriate, are moved from their stored portion as shown in dotted lines in FIG. 10 to their operative positions as shown in full lines therein and then the next adjacent locking strip is inserted so that its nose 126 engages with the locking tab and so on until the strips are inserted the full length of the beam.

Referring to FIGS. 4 and 5, the joint between a pair of components such as the components 44 and 46 is shown therein. This joint is associated as between the compression flanges of the two members by a pair of splicing strips 110 and 111, the strip 110 being rigidly afiixed to the component 46 and the splicing strip 111 being rigidly afiixed to the component 44 and the two being detachably secured together as by means of

fastening elements

113 and 115. As is shown in FIG. 7, the strip 111 is secured to the component 44 by means of a fastener 117 and there is a similar fastener 119 located in spaced relationship to fastener 117 as is shown in FIG. 4. When joined, and

6 for the purpose of aligning the two components 44 and 46, locating

pins

121 and 123 are provided in association with each splicing strip, this relationship being illustrated in FIG. 8 wherein the aligning pin 121 will be seen to be carried by the strip 111 and being projectable into an aperture of the other strip 110. These relationships are repeated for the other strip 110 but from the opposite side of the assembly as will be seen from a study of FIG. 4.

That is to say, on the right-hand side of FIG. 4 the locating pins are illustrated by reference characters 121' and 123', the individual strip securing elements being indicated in dotted lines as illustrated by reference characters 117 and 119'.

FIG. 4 also illustrates the manner in which the individual tension cables are fixed in end-to-end relation-ship. For this purpose, the cable 139 of component 44 is connected to the cable 132 of component 46 by means of the clevis joint indicated generally by reference character 134 including the removable pin element 136 for making and breaking this connection. As shown, the clevis part 138 is adjustably carried by the cable by the provision of a threaded connection with the threaded stem end 140 of this cable, a suitable lock nut 142 being provided to set any desired adjustment as between the clevis part 138 and its associated cable 130. The threaded stem 141) is connccted in any suitable fashion to the cable 130 as by the provision of a hollow sleeve portion 144 which receives one end of the cable 130 and is secured thereto. A similar condition prevails for the clevis part 146, the same being provided with a hollow sleeve portion 148 receiving the cable 132. It will be appreciated that when the beam is assembled, the cables 130 and 132 and their continuations at either end thereof will be under tension whereby the intervening web parts 80 will also be under tension. As has been previously mentioned, each individual section of a beam is deformed from its initial or original position when the components are attached together to form a rigid beam or arch structure. Thus, in beams 36 of FIG. 2, it 'will be appreciated that the lengths of the separate cables thereof are such that when the compression flanges are connected and the tension cables then joined, the compression flanges are deformed to assume the arch configuration, each compression flange being of substantially stralght form when in its relaxed condition. Thus, the degree of bow or arch is a function of the lengths of the individual tension cable means and of course this is subject to some degree of variation or adjustment by virtue of the clevis connection device shown in FIG. 4. In any event, whereas the individual sections of the beam are relaxed when not joined, they are subjected to a predetermined degree of pre-stress when the several sections are joined together to compositely form a beam structure.

Preferably, in order to accommodate for shear loads, the web means 80 is fabricated from material or fabric which is cut on the bias so that the threads thereof run diagonally substantially as is shown in FIG. 4. Or, this fabric may be in the form of a multi-layer web having the threads of one layer running radially and generally parallel to the compression and tension components and the threads of another layer running diagonally between the tension and compression components at approximately 45 thereto.

Referring now more particularly to FIG. 12, the construction of the end. components 38 to 40 will be apparent. In this figure, it will be seen that anchoring means 152 is provided for each end section. Each anchoring means is in the form of a base plate member 154 having

trunnion plates

158 and 160 rigidly afiixed thereto and with which removable trunnion plates 162 and 164 are cooperable. The trunnion plates of each pair present semicircular bearings but when joined cumulatively present circular bearing apertures to receive pin members 166 and 168 rigid with the opposite ends of a tube 170 which is rigidly attached to the end section assembly 40 by means of a gusset structure 172 bolted as at 174 to the compression flange 176 of the section 40 and rigidly attached as by welding 178 to the pipe or stiflener 1'70 which carries the pins 166 and 168. Thus, each end section of the beam is pivotally attached to its associated anchor member 152 to thereby avoid bending stresses in a direction perpendicular to the plane of the beam and to allow the beam to pivot back and forth as may be occasioned by movement of the structure as a whole due to weather loads or to allow the beam to be assembled on ground and rotated up into position. A reinforcing strip 180 is attached rigidly to the gusset assembly 172 and mounts .thereon an anchor member 182 by means of which one end of the cable 82 is rigidly aifixed to the beam structure as, for example, by anchor pin 184. The tension cable 186 of the section 40 is also anchored at one end to the rigidifying member 170 by providing a stud 188 thereon which passes through and is secured to the strut 170 by means of

suitable nuts

190 and 192.

Referring at this time more particularly to FIG. 13, the structure as shown therein represents a modified form of arch or beam which is comprised of a plurality of joined

sections

200, 202, 204, etc. As can be seen in FIG. 14, each such section incorporates a compression flange 206 formed by a pair of back-to-

back angle members

208 and 210. These angle members are joined together at intervals by through bolts 212 and are spaced apart in the manner shown in FIG. 14 by virtue of the interposition of spacing means such as

serrated washers

214 and 216 which serve to clamp upon portions of the web cables 218 which are looped over the through bolts 212. Each section is provided with a length of tension cable component 220 having an attachment link 222 at one end and a hook 224 at its opposite end whereby the several tension cable components may be atached together as shown.

The web cables 218 extend from a corresponding link 222 to a corresponding hook 224 and extend in backand-forth diagonal fashion as is shown, being attached fixedly to the tension cable 220 at spaced points therealong by suitable conventional crimped thimbles 226. Thus, each section when it is unattached is capable of compact storage. In order to detachably secure the ends of adjacent compression flange components together, suitable pairs of splice plates 230 and 232 are provided at one end of each of the sections exclusive of the end section 200. This construction is shown more clearly in FIG. 15 wherein it will be seen that the splicing plates 230 and 232 straddle the vertical legs 234 and 236 of the compression flange assembly 206. The ends of these plates are notched as at 238, see FIG. 13, to receive a through bolt assembly 240 and, as is shown in FIG. 15, a shear pin 242 is removably positioned to pass through the compression flange component of section 200 to cooperate with the through bolt 240 and rigidly connected to the compression flange of the

sections

200 and 202 together, the two splicing strips 230 and 232 being rigidly carried by the section 202 by means of suitable fasteners 244. Preferably, a spacer 243 is associated with each through bolt such as bolt 240.

As shown in FIG. 13, the construction of each end section 200-is quite similar to the construction shown in .FIG. 12. That is, each end section carries a stitfening tube 246 provided with pins or

trunnions

248 and 250 at its opposite ends and which stiffening tube is rigidly aflixed to the compression flange of the section 200 by means of a suitable gusset strap 252 and by virtue of direct connection to the compression flange in the region 254. The tension cable component 256 of the end section 200 is anchored by suitable eye elements 258 to the member 246 and the fabric retaining cable 260 is also suitably anchored to the member 246 as by an eye member 262.

As is shown in FIG. 14, the envelope or tensioned fabric 264 is affixed to the beam structure through the medium of the cable 260 which passes through the looped portion 266 of an attaching strip having opposite side edge portions or legs 268 and 270 suitably adhesively bonded or otherwise secured along its length to the underside of the envelope 264. Of course, another equivalent fastening means for the envelope may be utilized such as is shown in FIGS. 16 and 17, for example.

In FIG. 16, the envelope will be seen to include

panels

280 and 282 joined by any suitable quick-disconnect fastening means 284 and 286 to the corresponding edges of a securing strip or flap 288 which is joined as by stitching 290 to an anchoring strip having its opposite

side edge portions

292 and 294 overlying the outer faces of the

vertical legs

296 and 298 of the compression flange element 300 and adhesively bonded thereto.

In FIG. 17, the panels 302 and 304 are joined to the compression flange element 306 through the medium of suitable quick-

disconnect attaching means

308 and 310 which are carried by

anchor strips

312 and 314 adhesively bonded to the

horizontal legs

316 and 318 of the compression flange element and which may have

additional strips

320 and 322 similarly joined to the compression flange and to the

strips

312 and 314. In this case a sealing strip 324 is disposed over the crown of the compression flange assembly as is shown to seal the same.

Referring to FIG. 18, a particular arrangement using the beams as aforesaid in conjunction with an air-inflated structure is shown. In this FIGURE, a series of beams or

arches

400, 402, 404, 406 are pivotally connected at their opposite ends to anchor plates 408, one of which 1s shown in FIG. 18. Adjacent beams are joined by fabric panels 410 in which the panels are patterned so as to be more elastic in the direction across them, between ad acent beams or bows, and shaped so that as they'tend to lnflate, the threads extending between adjacent bows are substantially prevented from being tensioned. Thus, the longitudinal threads sustain substantially the entire tension load (as shown by the arrows in FIG. 18) and transmit the same directly to the bows, as shown. Because of this, the beams do not tend to be drawn together even under high inflation pressure, which drawing together would spill air from the structure.

At the same time, it will be appreciated that this type of structure eliminates the necessity for any anchoring means other than the means 408 shown. Further, it becomes a simple matter to open up such a structure by merely raising the beams about their pivot axes, much 1n the manner of a buggy top. In this instance, any pressurized air in the structure would of course be spilled, but the rigid nature of the beams easily supports the structure.

Structures such as shown in FIG. 18 can be semispherical in form, or the portion as shown may form the end or ends of a structure whose intermediate portion is semicylindrical, as shown in FIG. 1.

It is to be understood that certain changes and modifications as illustrated and described may be made Without departing from the spirit of the invention or the scope of the following claims.

We claim:

1. A beam structure for use in combination with a tensioned, flexible skin to impart structural rigidity to the skin in the direction of the plane containing said beam and to derive lateral stability from said skin, said beam comprising a relatively stitr' compression member, a flexible tension member and flexible web means joining the compression and tension members, said compression member being held in deformed condition by said tension member to impart tension to said web means and said tension member, said compression member including a pair of similar elements joined in back-to-back relation to present oppositely directed, laterally projecting flanges, portions of said web means being captive between said similar elements, said web means being in the form of a strip of fabric-like material beaded along one edge for captivity between said similar elements of the compression member, said material being arranged on a bias between the compression and tension members.

2. A beam structure for use in combination with a tensioned, flexible skin to impart structural rigidity to the skin in the direction of the plane containing said beam and to derive lateral stability from said skin, said beam comprising a relatively stiff compression member, a flexible tension member and flexible web means joining the compression andtension members, said compression member being held in deformed condition by said tension member to impart tension to said web means and said tension member, said compression member including a pair of similar elements joined in back-to-back relation to present oppositely directed, laterally projecting flanges, portions of said web means being captive between said similar elements, said web means being in the form of a cable extending diagonally back and forth between said compression member and said tension member with looped portions of such cable being held captive between said similar elements of said compression member and being fixedly secured to said tension member.

3. A structural beam comprising a plurality of separable sections, each section including a relatively stiff compression flange member, a flexible tension member and flexible web means joining the compression flange and tension members whereby each section may be compactly stored and is of light weight, said tension members being of less total length than the total length of said compression flange members whereby said compression flange members are held in deformed condition by said tension members and impart tension to said Web means and said tension members when the sections are joined, said web means being in the form of strips of fabric-like material arranged on a bias between the compression and tension members.

4. A beam structure for use in combination with a tensioned, flexible skin to impart structural rigidity to the skin in the direction of the plane containing said beam and to derive lateral stability from said skin, said beam comprising a plurality of separable sections, each section including a relatively stiff compression flange member, a flexible tension member and flexible web means joining the compression flange and tension members, said compression flange members being held in deformed condition by said tension members to impart tension to said web means and said tension member when the sections are joined, each compression flange member including a pair of similar elements joined in back-to-back relation to present oppositely directed, laterally projecting flanges, portions of said web means being captive between said similar elements, said web means being in the form of a strip of fabric-like material beaded along one edge for captivity between said similar elements of the compression flange members, said material being arranged on a bias between the compression flange and tension members.

5. A beam structure for use in combination with a tensioned, flexible skin to impart structural rigidity to the skin in the direction of the plane containing said beam and to derive lateral stability from said skin, said beam comprising a plurality of separable sections, each section including a relatively stiff compression flange member, a flexible tension member and flexible web means joining the compression flange and tension members, said compression flange members being held in deformed condition by said tension members to impart tension to said web means and said tension member when the sections are joined, each compression flange member including a pair of similar elements joined in back-to-back relation to present oppositely directed, laterally projecting flanges, portions of said web means being captive between said similar elements, said web means being in the form of a cable extending diagonally back and forth between said compression flange members and said tension member of each section with looped portions of such cable being held 1O captive between said similar elements of said compression flange member and being fixedly secured to said tension member.

6. A beam structure for use in combination with a tensioned, flexible skin to impart structural rigidity thereto in the direction of the plane containing said beam and to derive stability therefrom in the direction of said skin, said beam comprising a plurality of separable sections, each section including a relatively stiff compression flange member, a flexible tension member and flexible web means joining the compression flange and tension members, said compression flange members being deformed to tension said Web means and said tension members when the sections are joined, each compression flange member including a pair of similar elements joined in back-to-back relation to present oppositely directed, laterally projecting flanges, portions of said web means being captive between said similar elements, said elements also including upstanding leg portions disposed in spaced parallelism, and means for anchoring said skin to and substantially continuously along said leg portions.

7. A building structure comprising a tensioned outer skin assembly and a plurality of light weight, compactly storable beams for supporting the same, each beam being of arch-like form and being formed of separable sections disposed in end-to-end relation, each section including a relatively stiff and initially straight compression flange member, a flexible tension member and flexible Web means joining the compression flange and tension members, said tension members being of less length than said compression flange members whereby said compression flange members are arched to impart pre-tensioin to said tension members and said web means when the sections are joined, and means for joining said beams substantially continuously along their lengths to said skin assembly whereby said skin assembly imparts stability to said beams in the direction of each assembly.

8. A building structure comprising a tensioned outer skin assembly and a plurality of light weight, compactly storable beams for supporting the same, each beam being of arch-like form and being formed of separable sections disposed in end-to-end relation, each section including a relatively stiff and initially straight compression flange member, a flexible tension member and flexible web means joining the compression flange and tension members, said tension members being of less length than said compression flange members whereby said compression flange members are arched to impart pre-tension to said tension members and said web means when the sections are joined, and means for joining said beams substantially continuously along their lengths to said skin assembly whereby said skin assembly imparts stability to said beams in the direction of each assembly, there being means for pivotally anchoring the opposite end sections of each beam whereby to obviate bending stress is said beams upon movement of said skin assembly in directions normal to the plane of the beams.

9. A building structure comprising a tensioned outer skin assembly and a plurality of light Weight beams for supporting the same, each beam being of arch-like form and including a relatively stiff and initially straight compression flange member, a flexible tension member and flexible web means joining the compression flange and tension member, each tension member being of less length than a corresponding compression flange member whereby each compression flange member is arched to impart pretension to said tension member and said web means, and means for joining said beams substantially continuously along their lengths to said skin assembly whereby said skin assembly imparts stability to said beams in the direction of the skin assembly, there being means for pivotally anchoring the opposite ends of each beam whereby to obviate bending stress in said beams upon movement of the beams.

1 1 said skin assembly in directions normal to the planes of 9 2,992,649 3,036,583 References Cited by the Examiner 3,057,368

UNITED STATES PATENTS 5 8/1921 Nelson 135-1 6 7/1926 Harris. 7 177,592

11/1954 Freider et al 1892 3/1955 Freider et al 1353 10 4/1958 Worley 1892 X 1/1960 Mackey 135-1..1 7/1961 Swallow 13S4 5/1962 Miller 1354 10/1962 Seaman 135-111 FOREIGN PATENTS 1/ 1957 Great Britain. 12/1961 Sweden.

HARRISON R. MOSELEY, Primary Examiner.

REINALDO P. MACHADO, Examiner.

Claims

1. A BEAM STRUCTURE FOR USE IN COMBINATION WITH A TENSIONED, FLEXIBLE SKIN TO IMPART STRUCTURAL RIGIDITY TO THE SKIN IN THE DIRECTION OF THE PLANE CONTAINING SAID BEAM AND TO DERIVE LATERAL STABILITY FROM SAID SKIN, SAID BEAM COMPRISING A RELATIVELY STIFF COMPRESSION MEMBER, A FLEXIBLE TENSION MEMBER AND FLEXIBLE WEB MEANS JOINING THE COMPRESSION AND TENSION MEMBERS, SAID COMPRESSION MEMBER BEING HELD IN DEFORMED CONDITION BY SAID TENSION MEMBER TO IMPART TENSION TO SAID WEB MEANS AND SAID TENSION MEMBER, SAID COMPRESSION MEMBER INCLUDING A PAIR OF SIMILAR ELEMENTS JOINED IN BACK-TO-BACK RELATION TO PRESENT OPPOSITELY DIRECTED, LATERALLY PROJECTING FLANGES, PORTIONS OF SAID WEB MEANS BEING IN THE FORM OF A SIMILAR ELEMENTS, SAID WEB MEANS BEING IN THE FORM OF A STRIP OF FABRIC-LIKE MATERIAL BEADED ALONG ONE EDGE FOR CAPTIVITY BETWEEN SAID SIMILAR ELEMENTS OF THE COMPRESSION MEMBER, SAID MATERIAL BEING ARRANGED ON A BIAS BETWEEN THE COMPRESSION AND TENSION MEMBERS.