US2355248A - Building with air supported roof and method of constructing the same - Google Patents

Description

VENS, SUPPORT JR 2,355,248 ED ROOF AND e THE smvm 1942 Aug. 8, 1944. s

BUILDING WITH AIR METHOD OF con .Filed 5 Sheets-Sheet 1 STRUCTIN NOV. 26,

INVENTOR.

HERBBQZ' H. sm/mye.

1944- H. H. STEVENS, JR 7 2,355,248

' BUILDING WITH AIR'SUPPORTED ROOF AND METHOD OF CONSTBUCTING THE SAME Filed- Nov. 26, 1942 s Sheets-Sheet 2 INVENTOR. 7 H. sm/mgm.

Mesa

u /Q .4 NIQNEY 'BUILDING WITH AIR SUPPORTED ROOF AND METHOD OF CONSTRUGTING THE SAME Filed Nov. 26. 1942 5 She'ets-Sheet 4 Aug. 8,19 I H'H. STEVENS, JR 5 3 INVENTOR. #595597 H. 5751mm, J/e.

m \g iffw Aug. 8, 1944. H. H. STEVENS, JR I 5 BUILDING WITH AIR SUPPORTED ROOF AND METHOD OF CONSTRUC'IING THE SAME.

Filed Nov. 26, 1942 5 SheetS-Shee't '5 I N V EN TOR. 7 H5255 H 5 Til ENS, JP.

Patented Aug. .8, 1944 UNITED STATES PATENT OFlF'lCE BUILDING wrrn Am SUPPORTED noon AND METHOD or cons'ranc'rmc THE SAME Herbert H. Stevens, In, Bantam, Conn. Application November 26, 1942, Serial No. 466,982 12 Claims. (01. 108-1) My invention relates to building structures supported by air pressure and the method of build-,

ing the same. i

In general, embodiments of my invention c'omprise a peripheral support, a membrane of sub-.

stantially impermeable material serving as a roof element, means for anchoring the periphery of such membrane with respect to the peripheral support, and means for creating within themclosure formed by suchperipheral support and such membrane and the groundor floor or other bottom surface suitable increase of pressure of the air or other gas within such enclosure to thereby support such membrane in raised position. i r

Annealed low-carbon steelis preferred as the membrane roof element for reasons of structural and functional advantages, namely, that such steel is impermeable, i. e. precludes substantial air leakage, is available on the market in sheet form of great lengths, readily and effectively autogenously connectable at the lateral edges of such sheets to form varied dimensions of the roof, and possessing other attributes ad be carried out in any suitable manner. Desirably, steel or the like, in suitable form such as forged shapes, plates, perforated sheets and the like may serve as the anchoring material, which may-itself be. anchored within the concrete du'ring the molding stage. Auxiliary anchoring means may also be employed such as guy wires or the like suitably secured to the'anchorlng means or directly with the roof membrane or both.

Suiteble'means such as ducts or equivalent connected with the outlets of one Or moreair compressing means such as blowers exterior or interior, but preferably exterior, of the buildclosure' formed. within the building structure serve to increase the pressure of the air within such enclosure whereby the roof is raised and supported. Such air may be conditioned, namely,

till

- ing structure and discharging within the entill to remove dust and other ioreignmatter, also .controlled in temperature and otherwise pursuant to conventional practice.

Desirably, such an or other gas is preferably inducted through ducts extending below the peripheral support and leading through the fioor and delivering in the proximity of the floor, thus creating a free or conditioned air zone within the zone of operation of the operators or workmen or other occupants of the building structure.

Advantageously, air is exhausted from the enclosure or interior through the medium of towers enclosing exhaust ducts which connect with out/going ducts leading through the floor and extending below the. peripheral support to the exterior of the building structure. If desired, such self-exhausted air may be employed'to drive an air turbine which may be connected with respect to the air blower, thus reducing the power costs of air supply,

In structures embodying my invention, the earth, i. e. ground, serves as an advantageous bottom, upon which flooring of desired character may be installed. I

Structures embodying my invention may be constructed on beaches to extend over the water, applicable for enclosed shipyards, docks for submarines or the like, or hangars for seaplanes or the like, etc. The peripheral support of concrete or the like may be located wholly within the water, the water serving as the floor.

An advantageous method of building embodiments of my invention is carried out as follows:

Assuming an earthor ground-type ofstructure to be erected, the, earth or ground of the location for the structure is leveled off to approximate uniformity. About such leveled earth or ground, the peripheral support, say of concrete,

is formed in molds located in trenches or cleared ground surrounding such leveled earth or ground. The leveled ground intermediate the wholly or partly constructed peripheral wall serves as a temporary support for laying thereupon the steel sheets, i. e.,the roof membrane material, which are connected sheet to sheet at their contiguous sheets are connected toone another to complete the roof membrane, including shaping the periphery of the roof material to conform to that of the peripheral supp rt, and anchored relative to the peripheral wall. Air under pressure is then introduced within the enclosure of the buildcovered exteriorly with suitable roofing material such as asphalt, sheet roofing compositions, etc. for protection against corrosion and the like.

Preferably, a heat reflecting medium .is'incorporated on the underside of the roof structure to reduce heat radiation into the interior of the structure.

The peripheral configuration of the concrete or other peripheral support may be circular on noncircular. A circular or equivalent configuration is advantageous in that such configuration is self-bracing in support of the roof, Earth may be employed to interiorly shore the concrete or other peripheral wall in joint support of the roof structure; earth may also be employed to exteriorly brace the peripheral'support against. elastic instability failure.

A factory constructed pursuant to the inven tion, adaptable to present day requirements, is

typified by a structure of circular form, say twelve hundred feet in diameter which covers a clear spanof approximately twenty-six acres. Say 18 gauge of say soft-deep-drawing steel, which is procurable in strips of ninety inches in width. and six hundred feet in length may be employed as the roof membrane. The ends of the seam-welded steel sheets may be anchored to a steel plate, in concrete anchor ring. The exterior face of the steel sheets may be covered with one inch insulating board, applied with hot asphalt, upon which may be exteriorly applied, say, three-ply 20 year roofing.

' Assuming an increase of air pressure ofbut two and one-half ounces per square inch above atmospheric pressure, such roof assumes a dome formation, which may be designed to have an advantageous height at its center of say sixty feet. Such increasein air pressure is negligible to the occupants in that it represents merely the difference in air pressure between the top and bottom floors of a sixty story building, The initial stretch of the steel sheet for suchtwo and onehalf ounces per square inch increased interior pressur is approximately one percent, well within the safe maximum stretch of approximately twenty percent. of such type of steel. Increase of pressure of the interior air effects an elevation of the roof; however, the less the radius of cur,- vature of the roof, the greater is its resistance against air pressure, wherefore, in the circumstance of any tendency of the roof membrane to turn secured to reinforcing rods buried in the tinued increase of air pressure of approximately one ounce per square inch, an increase of. air pressure corresponding approximately to the difference in air pressure between the top and bottom floors of a twelve story building. Rippling of the roof membrane due to excessive wind, is precluded or reduced to safe limits by reason of the damping eifect of the continuously applied air pressure upon the interior face of the roof. The dome formation of the roof is advantageous in resisting internal pressure, and likewise resisting any suction or counterpressure arising by reason of external pressure differential caused by high winds, explosions, etc.

The above-referred to and other advantages are afforded, pursuant to the invention, by the employment of ductile material of the nature as above set out, serving as the prime membrane of the roof and by anchoring the same substantially completely about its periphery, whereby upon subjecting the roof material .interiorly of the building structure to relatively increased air pressure, the roof material is subjected at substantially all portions thereof to stretching forces creating tensile stresses within the roof membrane in all directions substantially parallel to bulge, as at any weaker or softer sections, and

consequent reduction of radius of curvature" of such bulged section, the greater is the resistance of such bulged section to bulge further.

With time the initial softening heat-treatment wears oif, and the metal may be farther stretched and thus cold work-hardened to improve its tensile qualities. In the circumstance ofunbalanced loads upon the roof membrane, as when covered by drifted snow, or sudden rain storm, the air pressure of the interior may be increased to overcome the weightof the snow drifts or water, without much danger of ruptureof the unloaded roof membrane. Uponelevation of the roof, say by an increase of two and one-half ounce per square inch air pressure, maintenance of the roof in elevategistatus is readily eilectcd at .i 9 9" the surface of the roof membrane. Thus under wind condition of say, gale velocity from any direction, or pressures varying in wide range, the tensile stresses mutually perpendicularly within the roof material serve to dampen any fluttering initiated in any portion of the roof material.

In the circumstance of an explosion exteiiorly of the building structure or even within the building structure, or by a gust of wind or any other suddenly applied load to a portion of the membrane, the tensile stresses within the roof membrane by virtue of excess pressure above that necessary in support of the roof serve to distribute such applied forces throughout the membrane and aid in transferring such energyto the air adjacent to the membrane wherein it will be mainly dissipated, The tensions existing throughout the roof membrane serve also to spread concentrated loads over wider areas, enhance the capability of the roof membrane to withstand such concentrated loads, and prevent the forces created by such applied concentrated loads from setting up damaging vibrations in or flutter of the roof membrane.

The advantages gained by subjecting the ductile material of the roof membrane to stretching forces are enhanced by the dome configuration resulting from the membrane being anchored peripherally to 'the vertically extending substantially rigid peripheral walls, and particularly in enhancing the damping effect of the roof membrane to forces created by such applied loads.

Such factory structure may be supplied normally with the one ounce increase of air by, say, sixteen fans, forcing air into a system of concrete ducts beneath the fioor, which have outlets in the floor, say, at thirty feet spacingQ Four exhaust towers each of, say, forty feet height may serve to collect the heated air which rises from men, machinery, lights and other sources and carry the same down through the floor through ducts disposed below the concrete peripheral wall.

. Danger of complete collapse is more apsychological problem than an actual one. Any single ventilating fan is suflicient to maintain the required increase of air pressure, as the assumed one ounce per square inch. The remainder of required iactory'is easily and rapidly built and possesses mg detail description and the drawingainwhich of exhaust towers, indicated above, is sufficient to support the roof in the event of collapse of the air-supplying system.

A factory having the structure typified above. results in the saving of nine-tenths oi. the steel in conventional construction. Such low overhead and upkeep costs. The factory is readily camouflaged, highly resistant to bomb blasts, and particularly suitable for twenty-four hour per day black-out operations Embodiments of the invention are particularly adapted to be erected in locations such as deserts, viz. the Sahara Desert, 'or in jungles and other locations in'torrid climates, in Iceland and other polar locations, requiring merely steel or' other sheets of suitable roof membrane material and in certain instances Portland or equivalent cements to be transported from the United States or other industrial centers, and accordingly a minimum of transported building mate rials. Y

The use of a reflecting ceiling prevents thermal radiation downwardly, thus rendering the structure of especial utility for locations all over the globe, inclusive of the torrid zone and the polar zones. The exhaust air from the hotter strata in the upper zones of the interior may be utilized by suitable heat exchange means to preheat or add heat to the infio'wing air in locationsof low temperature and during the seasons of low temperature, thus reducing the cost of temperature regulation within the'zones of operatlonof the occupants of the building. .7

Power may be obtained fromthe expansion of the air heated within the interior, by waste heat of men, lights and machinery and other sources andlor by sunlight on the roof or through a specially designed roof, transparent to solar radiation.

Power may also be obtained bysuitable manipulation from external temperature changes and/or barometric variations.

Entry from the exteriorinto the interior, and correspondingly in exit, is afforded for persons by means of revolving doors or equivalent; for

requisite for the entry or exit of a train, truck or the like. effects aleakage of'air pressure which is relatively inconsequential; the leakage efl'ect of a hole in the roof construction caused, say by a bomb, perhaps of twenty foot diameter, is readily compensated to maintain any desired increased air pressure. say, one ounce per square inch within the enclosure, by an increased air delivery by the normal fan system, and by the employment ofan auxiliaryfansystem, until the hole has been repaired or the air-leakage cause cured.

l Further features and objects of the invention will be morefully understood from the follow- Fig'; 1 is avertical sectional viewof one preferred embodiment of'the invention. Fig. 2'is aplan view of Fig. 1. I

Fig. .3 is a detail horizontal section or atype of entry for persons, airplanes, trucks or the like into the structure.

i Fig. '4 is a plan view of atype of norof the embodiment shown in Fig. 1. l

'Fig. 5 is a detail horizontal section of Fig. 4, on an enlarged scale through a blower section. Fig. 6 is a detail horizontal section of Fig. 4, on

an enlarged scale, through another blower section.

Fig. 7 is a detail vertical section on line I--'l oi! Fig. 4 01 a building construction embodying the invention, on an enlarged scale as compared .with

Fig. 1, and featuring a desirable arrangement oi flooring shown in Fig. 4, on an enlarged scale,

showing an approved arrangement of air-outflowing and air-inflowing ducts and related airinflowing ducts disposed in the floor of the structure.

89 of Fig. 8, On an enlarged scale.

Fig. 10 is a detail vertical transverse section, similar to Fig. 9, on an enlarged scale,showing one form of floor-disposed air outlet and an airsupplying duct connected therewith.

Fig. 11 is a'detail vertical section of an approved upper, i. e., exhaust terminus of a tower.

Fig. 12 is a diagrammatic view in vertical section indicating an initial stage in the erection of a building structure typified by Fig. 1 and other preceding figures.

Fig. 13 is a detail vertical section of a portion of Fig. 13.

Fig. 15 is a detailvertical section of a portion of a structure generally corresponding to that of Fig. 13 but showing another embodiment.

Fig. 16 is a detail sectional view corresponding to that of Fig. 13 but showing another construction.

Fig. 1'7 is a detail vertical section through the roof, illustrating ,a preferred arrangement of materials.

Fig. 18 is a detail vertical section through the roof, illustrating another preferred arrangement of materials. 1

Fig. 19 is a detail vertical section through the roof, illustrating-another preferred arrangement of materials.

accompanying Referring to the drawings, illustrating preferred embodiments of the invention, 50 indicates generally the roof, and 5| the peripheral wall support to which the periphery of the membrane of the roof 50 is secured. The earthor ground is indicated at 52.

As shown generally in Fig.1 and in greater detail and enlarged in Figs. 7, 13, 15 and .16,'theperipheral wall support 5| .may be'formed; within the. earthor ground 52; advantageously, the

peripheral wall 5| is of concrete formed by ripheral wall in support of the roof 50. 'In certain types of constructions embodying my invention. the earth at the locations indicated generally at 52b, exterlorly of the building structure, may also be retained for counter-shoring and.

Fig. 9 is a detail vertical section taken on line other purposes, referred to more fully herein after.

.As indicated generally in Fig. '7, the air under pressure introduced within the interior 54 of the building structure may be supplied by suitable ducts, such as indicated at 55, furnished. by one or more air compressors indicated generally at 55. Such ducts desirably extend below the peripheral wall support and may be spaced mutually with respect to one another, usually uniformly about the periphery of the building structure. As indicated in Figs. 2 and 4, there may be a plurality, say, nine stations, each furnished with its own air compressor 55 connected at its outlet with a main air-supply duct 55, each such air-supplying duct preferably leading to distribution air-supplying ducts 51, see Figs. '7, 8 and 9, discharging through outlets 58 located in the floor 53 of the structure. I

The exhaust of the air, see Fig. 1, is preferably effected by means of one or more towers 59 provided with ducts, the inlets of which are located within zones of relatively higher tempera-.

tures of the interior of the building structure, advantageously above the zones of operation of the operators or other occupants of the building structure. municate at the bottoms thereof with air outgoing ducts 50, See Figs. 8 and 9, which extend under the peripheral wall 5i to the exterior of the building. As indicated-in Fig. 4, four such exhaust towers 59 have been found desirable. desired, the air out-going duets 50 maybe 10- cated in close adjacency with respect to the airingoing ducts 55, as by placing each outgoing duct 50'side by side anddntermediate twoingoing ducts 55, indicated generally in Fig. 4 and I in enlarged detail in Fig. 5. Such arrangement is advantageous in minimizing the amount of' earth required to be removed in forming the troughs in the earth or ground in which the respective ducts are located; also, in afiording the utilization of an air turbine motor, such as indicated at 6| in Fig. 5, through which the outgoing air is passed to drive the same as a motor in geared relation with one or both of a pair of air compressors 55, 55, as indicated in Fig. 5, supplying the compressed air, thus reducing the power for driving the air blowers 55, 55, referred to more fully hereinafter. Such side-by-side relationship of a heated air outgoing duct and an air ingoing duct is advantageous when it is desired to effect thermal interchange of the concerned air flows, described more fully hereinafter.

The peripheral edges of the roof membrane are anchored with respect to the peripheral wall' by any suitable means. One such approved anchor-*- age is indicated in Figs. 13 and 14, showing the roofmembrane 5| seam-welded at its longitudinal, i. e., peripheral edges to a suitable anchoring member such as a bar indicated at52, say, of cast steel, or a heavyplate or the like of suitable material, itself anchored within the upper. portionof the peripheral wall 5|, as by molding the same within the concrete peripheral wall, such anchoring member I5 may be also supplemented by suitable reinforcing elements such as steel wire indicated generally at 53, and/or perforated sheets of metal or the like, the concrete, and connected at its upper edge portions with such anchoring member 62, or directed -to the membrane 5|. Such supplemental anchoring means 51 "may have anarcuateconflguratlon, n as indicatedin Fig. 13 for strain stabilizing advantages.

The ducts of such towers59- com-- also molded within In Fig. 16, the roof membrane 6| is shown seam-welded at its peripheral edges to a bar,

plate or like anchoring member 55, in turn seamwelded or otherwise rigidly connected to wire, or

perforated sheets, etc. indicated at 65, molded or.

otherwise rigidly lodged within the concrete or other peripheral wall 5|; such anchoring means may be lodged within the peripheral wall to extend downwardly and terminating arcuately at its lower end, as indicated in Fig. 16.

The configuration of theperipheral wall 5|, as indicated in Figs. 13, 15 and 16, may be varied, to withstand'the imposed stresses and strains incl: dental in the support of the roof membrane and associated roofing materials under varying weather conditions, and depending upon the configurations of the peripheral wall, its manner of lodgement within the ground or other support,-

and other concerned factors. Thus in Figs. 13, 15 and 16, the peripheral wall indicated as of concrete may have variant general quadrilateral configurations, and its upper face preferably arched to provide a substantially smooth rounded surface against which the roof membrane is brought in its varying positional relationship therewith incident to varied increase of internal atmospheric pressure. In Fig. 13, the peripheral wall is shown shored interiorly by. ground lodged thereagainst interiorly of the building structure for a height above the floor level 53. Fig. 13 also illustrates the peripheral wall countershored by ground lodged exterlorly against the peripheral wall 5|. In Fig. 16, the peripheral wall 5| has a cross-sectional configuration generally that of a parallelogram and having a height; greater than its thickness; also shored interiorly to a height greater than that indicated in Fig. 13 as well as countershoredfor full height exteriorly, as indicated at 525.

' In Fig. 15, the roof membrane is shown anindicatediat 51 by means of earth anchors 55.

, As one manner of constructing a building embodying the invention, the procedure may be as follows, it being understood that the cited specific steps may be varied, as is apparent, to attain the objects and purposes of the invention.

As indicated in Fig. 12, assuming the structure to be erected on earth, the ground denoted generally i5, is substantially leveled at its upper surface H, upon which are laid, see' also Fig. 4, lengths of sheets I2 of the'roof membrane 5|, say steel sheets. The lateral edges of these sheets are welded continuously, as by electric seamwelding, soldering or the like.

About such leveled surface 1| of'the earth,

.trenches are dug for reception of the material of indicated. Assuming the air blowers to be located exterior-1y of the buildingstructure, trenches are dug exteriorly of the peripheral wall for locating suitable housings forsuch air blower stations. Desirably. these air blower stations are spaced about the peripheral wall. Openings are provided in or under .the peripheral wall communicating with such air blower stations. Leading from such -wall openings, tunnels are dug interiorly of the leveled ground and at a -level or ripheral wall, at desired locations, are also provided for the entry and exit ofpersonnel, trucks, airplanes, etc., depending upon thelltillzatlon of the building. i

Upon installation of the air blowers, air under compression may then be supplied under the roof membrane; thus elevating the same relative to the leveled ground. In Fig. 12, elevation of the roof membrane is indicated by comparison of the roof membrane in elevated position, de-

let 58 may be effected by means of a ba-flle 16,

shown pivoted at oneend and regulated as'to" its angle of diversion by means of an adjusting rod11 provided with a hand-knobgl8jor'e'quivalent. Such dual air blower stations are denoted 14 in the drawings, showndistributed about the periphery of the peripheral wall 6 I.

Fig. 'B'indicates' an app , vedyarrangementof air blowers 56, 56 combinedfwith'an' air-turbine motor 84 and associated main and auxiliaryidriw ing means, assembled in a single, station, denotnoted at 12a in dot-and-dash outline, with its flat position, denoted 12 in full outline.

As indicated by Fig. 12 and disclosed generally hereinabove, advantages are attained pursuant tomy invention by limiting the elevationof the roof membrane to the configuration of a shallow dome. In the instance of an embodiment of the invention of substantially circular form of the order of 1200 ft. in diameter and a vertical height of the center of the dome of the order of 60 ft. above a plane passing through the peripheral anchorage of the roof membrane, referred to hereinabove, the ratio of such vertical height of the dome to the diameter of the peripheral wall is approximately 1 to 20.

The average stretch of annealed low-carbon steel for the indicated increase of air pressure is about one percent, which is sufliciently above the yield point to insure a permanent deformation of theroof intoa smooth dome of low vertical central rise. Figs. 1, 7, 12, 13 and 15 indicate generally a range of dome configuration contemplated by the invention. Steel has a maximum elongation of abouttwenty percent; hence there is provided an ample factor of safety for variant heighths of shallow dome formations.

Upon attaining sufllcient elevation, the remainder of the a ground above the desired floor level is then removed." The flooring, including the discharge openingsof the air inflowing ducts, may now be completed. The desired air exhaust towers may also be erected at this stage, including the air outgoing ducts leading therefrom.

A preferred form of air delivering duct systems including floor discharge openings is illustrated generally-in Figs. 8, 9 and 10; as shown, such ed 13; these stations may be distributed about the peripheralwall 5|. the blowers 56, 56 supply compressed air through the air ducts 55, 56;. such air blowers may be driven directly by electric motors, indicated at 18, 18 and/or by internal combustion engines. which latter may serve as stand-by power sources. 60 represents the duct conveying air exhausted from the interior of the building structure, under pressure in excess ofthat of the outer atmosphere, and such air under increased pressure may be passed through the indicated air turbine 6| operating as a motor, the. shaft of which may be suitably geared relative to the respective shafts of the associated air blowers 56, 56, usually by the intermediation of ratchet clutches, whereby the power imparted by the exhaust air to the shaft of the turbine motor 6| is effective as increments to and/or the drive of the air motors 56, 56jointly or singly.

Means of entry and exit for personnel, trucks,

railroad trains, etc., and for the produgts of manufacture, such as tanks, airplanes, etc. for which the structure has definite utility attributes, may be provided as preferred. In Figs. 1, 2, -3 and 4, there is indicated a combination entry, and exit for personnel in the form of three revolving doors denoted generally 80; also a set of doors SI, 82, operable as canal lock gates as for trucks, tanks and like vehicles. Such unitary arrangement of station of entry and exit may be provided in number about the periphery of the peripheral wall 5|,

alternate closing means in case of failure, such as is indicated at 80a, for the set of revolving doors 80.;

Treatment of the roof in'addition to the pri-- mary roof membrane may be carried as preferred. Desirably the membrane is protected by outer weather-resisting surfaces, also for ther rnal insulation, and particularly with a light and heat reflecting surface applied on the inward sur- Assuming the air blowers or compressors to be located exteriorly of the. peripheral wall, as is indicated in Fig. 6, the main air inflowing ducts 66 may be arranged to be respectively connected to parallelly arranged air- blowers 56, 56, driven,

say, by an electric motor, indicated at 15. Such air blowers may be driven by gasoline or other explosive engines, a preferred, or alternatively by employing such gasoline engines as stand-by sources of power, in the event of failure of electrical power. Each of such main air innowing ducts 66 may be connected .with a series of distribution ducts 61 as in the manner indicated in Fig. 8. As indicated in Figs. 9 and 10, the control of the extent of diversion of the infiowing air conveyed through any distribution duct 51 to and through any individual floor or other outface of the roof membrane. Typical of such additive attributes, I have illustrated in Fig. 17

the roof membrane 6|, say of sheet steel, 2. reflecting surface of aluminum, sprayed or in the form of foil, may be applied upon its inner face, indicated at 86. Upon the exterior of the roof membrane 6|, there is indicated a thickness 86 of insulation such as conventional insulation board, which may be applied in the form of layers. sheets or the like, which may be connected to one another at their lateral edges, for additional strength or to form the primary membrane. Also, an outermost layer of roofing material such as asphalt or the like, indicated at 81, or asphalt or other approved roofin sheet In such arrangement, 7

. ri ls known as "Homosote" Celotex, Ma-

sonite, etc., or plastics such as cellulose acetate, methyl methacrylate, etc.

Preferably, such material Blshould contain entrapped air for heat insulation. It may be of a relatively ductile material or formable so that the pressure within the dome may be reduced after elevation, or it maybe of a more elastic material in order to permit collapsing the roof or vary the volume, as when used as a storage tank or energy source. h

81 represents the exterior surface which may be the weather-resistant surface of the primary membrane, or a coat-of paint or other protective surface, or built-up felt roofing.

Fig. 19 represents a composite roofing including a similar type of membrane as in Fig. 1'7 or Fig. 18 showing a method ofsound proofing the under surface. .87 represents the roofing surface, 86 the insulating material, 8| the primary membrane which is substantially impermeable to air and moisture vapor in the air. 88 represents a sound absorbing material of sprayed felting flock, applied blanket insulation, etc., 85 represents the reflecting inner surface which in this case is ervious to permit sound penetration into the sound absorbing material 88. The reflecting surface 85 may be sprayed metal on the sound absorbing material 88 or a perforated foil applied to the exposed surface of the sound absorbing material.

Flooring for the surfacing of the ground may be selected as preferred. Usually, concrete or the like is applicable for a large proportion of industrial uses.

vIf desired, exhaust openings may be located in proximity of the zones of operation of the operators, particularly for operations giving rise to fumes or other obnoxious gases.

Lighting of the enclosure is readily afiorded by floor stands advantageously of the ortable types, the efficiency of which is. increased by the reflecting surface of the roof, above described.

Air may be introduced continuously at floor level and withdrawn at higher temperature and volumn continuously from the higherrtemperature zone near the roof, or it may be introduced intermittently say at lower temperature at night and discharged at higher temperatures during the day, thus taking advantage of the daily temperature cycle. It may also be introduced at high barometric pressure and discharged at low etc., is utilized by my invention.

This type of construction is adaptable to a means of generating power from sunlight. A preferred method is to make the primary'membrane of a high strength plastic with low modulus of elasticity, say 300,000 pounds per square inch or less, transparent to solar radiation, of say .01 mu to 4.0 mu wavelength but opaque to low temperature heat radiation of say 4.0 mu to 20 mu wave lengths. It is desirable by means of laminations separated by small disks of material or by other means to form entrapped air spaces to thus increase the heat ilnsulation of the membrane and reduce heat loss by conduction through When used, say as a factory, waste heat from lights, mechinery, and occupants of the dome will also provide useful air expansion and tendency to increase the efiiciency of operation of the ventilating equipment, if not actually providing excess power.

If'preferred, as is indicated at in Fig. 7, a thermal exchanger may be employed for heating or, cooling the supplied infiowing air. Such thermal exchanger may be associated with suitable air flltering means, scrubber or the like for the removal of dust or other foreign material.

Generally speaking, for maintaining relatively low pressure within the enclosure of the building structure, the blowers are operated at relatively low speed. It is advantageous to employ air blowers driven by a two speed electric motor, and arranged, say as airs, for supplying air at relatively low pressure, both blowers may be concurrently operated, and when it is desired to supply air at relatively higher pressures, but one blower may be operated, at its higher speed, the other blower being shut off and its delivery opening blocked by suitable means.

It will be observed that the bafiles l6 are so arranged in angularity within their respective distribution ducts 51 whereby in the circumstance of supply of inflowing air to any distribution duct from one inlet only. i. e., from one main duct only, uniformity of distribution of the air through the floor outletsEB is nevertheless attained, namely, by the angularity of such baflies 16 which are disposed more closely to such main duct, setting up eddy. currents which tend expanse of utilization of the full square-footage of the floor space.

Whereas I have described my invention by reference to specific forms thereof, it will be understood that many changes and modifications closure to thereby support said membrane inmay made provided theydo not depart from I the scopeof the claims; l

IclaimL --1L A building structure comprising avertically I extending relatively rigid peripheral support, a

membrane 'ofsubstantially impermeable ductile metallic material serving as a primary roof element shaped at its periphery toconform to that of said peripheral support; means for anchoring the v periphery of said membraneiwith respect to said peripheral support, means for creating within the" enclosure formed by said peripheral support and i said-membrane and the floor. or bottomsurface; increase of pressure of the air within such' en raised position, thereby cngenderingwithin said roof membrane tensile stresses in all directions substantiallyparallel to the surface of said root.

membrane with respect to said peripheral support; and means for creating within the enclo- A "sure of the building structure increase of pressure of the atmosphere therein to thereby support said roof membrane and engenderflwithin said rpofmembrane tensile stresses in alldirectionssubstantially parallel to the surface of said roof membrane.

' 6; A building structure comprising a vertically ,extending fixed perlpheral support; a roof membrane of substantially impermeable ductile material sh'apedlat its periphery to conform to that ,ofsfldperipheral sup'port; means for anchoring substantially the entire periphery of said roof I115:

membrane withjre'spect to said peripheral su portyand means forcreating within the enclosure-of the building. structure increase of presmembrana'andheat reflecting means carried by of the building structure. I I

said roof membrane internally or the enclosuref 2. A building'structure comprising a vertically 3 extending relatively rigid peripheral support}: aflf membraneiof substantially impermeableaductile port and said membrane and the floor or bottom surface increaselof pressure of the air within such enclosure to thereby support said membrane in a.

sure ofthe atmosphere therein to thereby elevate and support said roof membrane and engender within'said roof membrane tensile stresses in all directions substantiallyparallel to the surface of said membrane.

q 7:tA-buildingstructure comprising a. vertically extending fixed peripheral support; a roof membrane of substantially impermeable ductile material shaped-at its periphery to *conform to that V of said peripheral support; means for anchorsupport; and means for creating within the enraised position, thereby engendering 'within said roof membrane tensile stresses in all directions substantially parallel to the surface of said roof membrane, and light reflecting means carried by said roof membrane internally of the enclosure of the building structure.

3. A building structure comprising a vertically extending relatively rigid peripheral support, a

membrane of substantially impermeable ductile metallic material serving as a primary roof element shaped atits periphery to conform .to that of said peripheralsupport, means for anchoring v theperipheryof saidmembrane with-respect to I said peripheral support, means forcreating with -in the enclosure formed by said peripheral support and said membrane and the fioor'or bottom surface increase of pressure of the air 'within such enclosure to thereby support said membrane in raised position, thereby engendering-within said roof membrane tensile stressesin all direc: tions substantially parallel to the surface of said roof membrane, and heat and light reflecting, means carried by said rooi' membrane internally of the enclosure of the building structure.

4. The method of constructing a building structure provided with a roof supported by relatively increased internal pressure which comprises employing ductile material as the primary material of the roof and subjecting such roof material torelatively increased pressure internally of the building structure to thereby stretch such roof material to its desired final conflgura tion by the action of such increased internal pressure, thereby engendering within said roof mate- Y substantially the entire periphery of said root ing substantially the entire periphery of said roofjmembrane with respect to said peripheral closureof the building structure increase of pressure of theatm'osphere therein to thereby elevate and stretch said roof membrane beyond the elastic'limit and support said roof membrane and engender within said roof membrane tensile stresses in alldiregions substantially parallel to the surface of said roof membrane.

8. Abuilding structure comprising a vertically extending fixed peripheral support, a 'roof membrane oi. substantially impermeable ductile material shaped at its periphery to conform to that of'said peripheral support; means 'for anchoring substantially the entire periphery of said roof membrane with respect to {said peripheral support, and jmeansfor creatingtwithin the enclosure ofthefbuilding structure increase of pressure of the atmosphere therein to thereby elevate and i smooth-out unevennesses in said roof membrane 9 and engender within said roof membrane tensile stressesin all directions substantially parallel to the. surface of said roof membrane 9. The method of erecting a building structure provided with a roof supported by relatively: increased internal atmospheric pressure, which comprises providing a vertically extending fixed peripheral anchorage; providing a membrane of substantially impermeable ductile material shaped ture provided with a roof supported by a relatively increased internal atmospheric pressure, which comprises providing a. vertically extending relatively fixed peripheral anchorage; providing sheets of substantially impermeable ductile material; connecting such sheets to'one another to form a substantially impermeable roof membrane; shaping the periphery of the thus formed anchorage; securing the peripheral edge of such roof membrane to such peripheral anchorage;

(peripheral anchorage; providing a membrane of substantially impermeable ductile material shaped at its periphry to conform to that of the periph-.

eral anchorage; securing the peripheral edge of such roof membrane to such peripheral anchorage; and supplying increased atmospheric pressure within the enclosure of the building structure to elevate and stretch such roof membrane beyond the elastic limit and support the thus secured roof membrane and engender within said roof membrane tensile stresses in all directions I roof membrane to the periphery of such peripheral substantially parallel to the surface of said roof membrane.

12. The method of erecting a building structure provided with a roof supported by a relatively increased internal atmospheric pressure, which comprises providing a vertically extending relatively fixed peripheral anchorage; providing sheets of substantially impermeable ductile material; connecting such sheets to one another to form a substantially impermeable roof membrane; shaping the periphery of the thus formed roof membrane to the periphery of such peripheral anchorage; securing the peripheral edge of such roof membrane to such peripheral anchorage; and supplying increased atmospheric pressure within the enclosure of the building structure to elevate and smooth-out unevennesses in the roof membrane and support the thus secured roof membrane and engender within said roof membrane tensile stresses in all directions substantially parallel to the surface of said roof membrane.

HERBERT H. STEVENS, Ja.

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