Building construction

J. E. WHEELER

BUILDING CONSTRUCTION

Oct. 20, 1964

Filed Oct. 27, 1958

3,153,302

Sheets-Sheet I

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ATTORNEYS

J. E. WHEELER

BUILDING CONSTRUCTION

Oct. 20, 1964

Filed Oct. 27, 1958

3,153,302

Sheets-Sheet 2

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INVENTOR.

James E. Wheeler

BY

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ATTORNEYS

J. E. WHEELER

BUILDING CONSTRUCTION

Oct. 20, 1964

Filed Oct. 27. 1958

3,153,302

Sheets-Sheet 3

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INVENTOR.

James E. Wheeler BY

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ATTORNEYS

Oct. 20, 1964

J. E. WHEELER

3,153,302

BUILDING CONSTRUCTION

Sheets-Sheet 4

27, 1958

Filed Oct.

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INVENTOR.

James E. Wheeler

BY

ATTORNEYS

3,153,302

Patented Oct. 20, 1964

United States Patent Office

153 302

BUILDING’CONSTRUCTION

James E. Wheeler, 2256 Kent Blvd. NE., Grand Rapids, Mich.

Filed Oct. 27,1958, Ser. No. 769,790 5

Claims. (Cl. 50—49)

This invention relates to building construction in general, and more particularly to circular buildings and a novel and economical roof construction therefor. This io construction includes a method of prestressing concrete which makes possible the obtainment of more economical and greater roof spans than has heretofore been possible in concrete construction.

There has long been a need for buildings having un- 15 obstructed, open and expansive floor areas. Such buildings have use as civic auditoriums, aircraft hangars, and the like. Numerous different structures have been proposed and numerous different materials have been tried in the construction of such buildings. Steel and concrete 20 materials have been used largely because of their fireproof nature. However, long structural steel members create a considerable shipping problem. They are also expensive to move from one location to another. Concrete, on the other hand, has heretofore required pouring forms which 25 must be shipped to the job site, erected, and later dismantled.

The expense and shortage of structural steel has in many instances greatly served to encourage the use of reinforced concrete, despite the disadvantages mentioned. 30 Concrete may be formed to different shapes and forms and is fireproof. Many innovations and different architectural designs have proven possible with the use of concrete and the aesthetically pleasing results have brought increased demands for further use of concrete for building 35 purposes.

As mentioned, thus far concrete buildings have been principally constructed by pouring concrete in forms having suitable reinforcement or by using precast and reinforced concrete slabs or joist. This form of construe- 40 tion requires the repair and maintenance of pouring forms, their erection and disassembly, and involves an appreciable shipping problem in moving the forms about. Furthermore, such construction is very limited as to the spans that are obtainable. 45

Reinforced concrete has been found to be relatively weak in tension. To compensate for such weakness a relatively new concept in concrete construction has been introduced. This method is known as prestressed concrete. Although prestressed concrete is generally considered to be beyond the experimental stage, its use is still very much limited to either linear prestressing of steel inserts, as in beams and slabs, or to circular prostressing of steel bands (which is more posttensioning) as in forming circular storage tank walls and the like. ⁵⁵

Prestressed concrete may be classed as concrete having either pretensioned steel inserts or posttensioned steel inserts. The steel used is of a high tensile quality and may be in the form of wire ropes, strands or single length steel bars. In prestressing, the reinforcement is placed in ten- θθ sion before the concrete is poured and the subsequent release of the tension places the concrete itself in compression. In posttensioning the concrete is poured about the reinforcement but is not bonded thereto. Subsequently, a tension force is applied to the steel reinforcement, after ⁶⁵the concrete has set, and is maintained to hold the concrete in compression.

This invention teaches a wholly new concept in prestressed lightweight thin shell concrete construction. Pretensioning methods are used during the building construe- ⁷⁰tion in forming the building roof structure. An inverted conical shaped roof makes use of such pretensioning methods to obtain longer spans than have been heretofore known in similar type building construction. An “umbrella” form of roof is provided in which the entire dead load of the roof is carried by a central column. This permits large unsupported openings to be provided in exterior walls under the outer periphery of the roof structure. The roof forming framework is tensioned in the course of construction and, while in tension, has a lightweight air-borne concrete aggregate applied thereto. No concrete forming materials are required. After the concrete has set, the tension is relived. The dead weight of the roof structure is then counteracted by a compressive force within the concrete itself due to the tensile force remaining in the roof framework.

It is an object of this invention to disclose a new concept in prestressed concrete construction. The pretensioning methods of this invention may be used to provide a long span thin concrete roof shell in which no concrete forming materials, as such, are required.

Another object of this invention is to disclose a method of building construction in which one simple operation gives pretensioning advantages heretofore obtainable only by elaborate and costly posttensioning means.

Still another object of this invention is to disclose a novel and economical roof structure for a large building. The proposed roof structure is of a thin shell concrete aggregate under compressive forces and wholly supported by a central column. The roof structure includes radial beams integral therewith which serve to compensate for negative wind loading on the long unsupported roof span.

A further object of this invention is to disclose a building structure making use of the proposed roof construction and having only thin shell enclosing walls which serve essentially as curtain walls and means for stabilizing the roof shell against unequal loading caused by high winds or snow.

A still further object of this invention is to disclose a building structure constructed to enable having large portions of the enclosing wall removed to provide an expansive opening and without requiring additional structural support within the building structure itself. The opening may be closed and relocated elsewhere, if desired, as in true curtain wall construction.

An even further object of this invention is to disclose a building structure in which all service utilities such as heating, ventilating, plumbing and electrical, may be located in a compact central location.

These and other objects and advantages in the practice of this invention will be more apparent in the illustration and description of a working embodiment of the invention, as hereinafter set forth.

The building hereinafter shown and described illustrates the use of the principles of this invention as an aircraft hangar. It will be appreciated that the principles of construction disclosed in the form of building described have other uses.

The hangar disclosed is intended to accommodate several different types of aircraft and aircraft having different wing spans, tail heights, etc. Accordingly,, the interior of the hangar must include a high ceiling and a large unobstructed floor area for ease of maneuverability in locating and rearranging the airplanes within the hangar space as well as for ingress and egress at the common opening in the hangar. Furthermore, a large wall opening must be provided within the side of the buidling structure to enable the airplanes ease of ingress and egress despite their unusually wide wing spans.

An aircraft hangar of the type disclosed may include certain features set forth in my copending applications Serial No. 691,404, filed October 21, 1957 and entitled

3,153,302

Aircraft Hangar, now Patent No. 2,964,144, and Serial No. 763,974, filed September 29, 1958, and entitled Circular Aircraft Hangar and Method of Construction Thereof. Such of the comments and features in these copending applications as are applicable in this construction will be referred to only generally since the details are available in such other cases. Thes features include having a circular hangar structure, an annular turntable ring for relocating aircraft within the hangar, and a rotatable closure panel for closing the opening in the hangar wall and which requires no conventional hinges, rollers or tracks.

In the drawings:

FIG. 1 is a perspective view of a circular building made in accord with the teachings of this invention and useable as an aircraft hangar.

FIG. 2 is a cross sectional view of the disclosed hangar during the initial stages of construction.

FIG. 3 is a cross sectional view of the disclosed building during another more advanced stage of construction.

FIG. 4 is an enlarged perspective view of a part of the roof structure during the initial stages of construction.

FIG. 5 is an enlarged perspective view of a part of the roof structure framework as erected and under tension.

FIG. 6 is a top view of a part of the roof structure framework, prior to having the concrete aggregate applied thereon.

FIG. 7 is an enlarged cross sectional view of the building roof structure as seen in the radially disposed vertical plane therethrough.

FIG. 8 is an enlarged cross sectional view through the hangar roof structure of FIG. 7 as seen in the plane of line VIII—VIII and looking in the direction of the arrows thereon.

In brief, the disclosed aircraft hangar is a circular structure having as much as 25,000 square feet of unobstructed floor area. The roof structure is of the umbrella type and is made of prestressed lightweight thin shell concrete. A roof supporting column is provided centrally of the building. A pair of concentrically disposed annular rings with high tensile wire rope or rods disposed therebetween, are erected upon this column. The inner annular ring is a tensile ring that is slidable on the central column. This permits the roof to be formed at the base of the column and to be later erected and tensioned on the column. The outer annular ring is a compression ring and may take the form of a sixty sided polygon. The roof tendons are connected to the annular compression ring.

After the roof is framed and is raised on the roof supporting column, tension is applied to the roof forming tendons. Thereafter, an air-borne lightweight concrete aggregate or other cementitious material is applied thereto. The roof is covered on both sides and preferably by a process known as guniting.

After the roof covering has set the external tensioning is released causing the roof tendons to apply a vertical lift force of approximately 3,000 pounds each to the outer annular compression ring. The inverted cone shaped concrete roof shell is then under compressive forces which more than compensate for the dead weight tensile load of the roof structure.

Thereafter an external wall is provided under the outer periphery of the roof to enclose the space thereunder. This is not a load bearing wall in the normally accepted sense. It is more of a curtain wall. Accordingly, a large expanse of the wall may be left out or made removable to provide for a hangar door. The roof and wall are engaged only aS necessary to guard against unbalanced forces on the roof due to wind, snow, or other uneven loading.

Certain other detail features of particular significance in their own right, will be described in the detailed description which follows.

The circular aircraft hangar 10 includes an inverted conical roof structure 20 supported on a central columii 30 in the manner of an umbrella. The area Under the roof 20 is enclosed by an external circular wall 40. An opening 50 is provided in the wall 40 of the hangar. Iff this instance, the stationary wall 40 represents four-fifths; of the wall periphery. The opening 50 is inclusive of the remaining one-fifth of the wall periphery and is sufficiently large for aircraft to pass through without interference. The opening 50 may be closed by a rotatable door panel in the manner taught in my other copending applications.

The hangar building 10 requires a centrally disposed foundation 11 for supporting the columns 30. An annular foundation 12 is provided concentrically about the central foundation 11. The foundation 12 defines the area to be enclosed. As will be shown, the foundation 12 also serves as ballast to counteract the pre-stressing force imposed on the roof structure during its erection. The foundation 12 also serves to support the thin shell exterior wall 4®. The foundation 12 may be further used as a base upon which to support the closure panel for the wall opening 50. A turntable, ring pit 13 is provided near the inner periphery of the foundation 12. A turntable ring 14 is provided within the pit 13. The inside' Wall of the pit 13 is formed by an intermediate annular foundation 15. A concrete slab floor 16 is providedwith its outer periphery terminating at the inner edge of the turntable pit 13 and supported on the foundation 15.

The roof structure 20 is formed first as a framework 20' about the base of the central column 30. The framework 20' comprises an outer annular ring 21 of the size of the foundation 12 or larger. The annular ring 21 is preferably of tubular construction formed to a closed circular configuration. The ring 21 is intended to serve as a compression ring, as will be shown. It may be built up of short tubular sections joined together by suitable connectors and forming a many sided polygon. A smaller annular ring 22 is provided concentrically within the outer ring 21. The ring 22 is of a size fitting closely about but being relatively movable on the central column 30. The ring 22 is used as a tensile ring, as will be shown. The roof forming rings 21 and 22 are joined together by radially disposed, elastic high tensile wire rope members which form radial ties or tendons 23. The wire rope members 23 are elastic in the conventional sense as this term is applied to high tensile wire rope or rods well known to those skilled in the art relating to prestressed concrete construction; that is, they exhibit a restoring force, when elongated by a tensile stress not exceeding their elastic limit, substantially equal to: the tensile stress causing elongation. These radial tendons 23 include an upper strand of three-eighths inch wire rope 24 passing over the inner annular tensile ring 22 and returning as a bottom strand 25. The ends of the wire rope strands 24 and 25 are fixed to the outer annular compression ring 21. A clamp fastener 26 may be used for this purpose.

The spaced wire rope strands 24 and 25 are subsequently used to form radial beams integral with the roof structure. Towards this end, spacer bars 27 are disposed between the wire rope strands and have their ends 28 formed for engagement thereto. The bottom of the spacers 27 are formed to include an extension 74 upon which a lightweight channel iron member 73 is secured. Such channel member 73 serves as the bottom edge of the roof beams which are formed about the tendons 23 and as an integral part of the roof structure.

The inner annular tensile ring 22, of the roof framework 20', is received on a saddle support 31 which is slidably adjustable on the central column 30. The various pairs of roof stringers or tendons 23 are assembled radially between the rings 21 and 22, and are tuned for uniformity. A series of annular reinforcing bars 35 are disposed between adjacently disposed tendons 23 and are arranged concentrically between the outer and inner annular rings 21 and 22; respectively. These are provided

3.153.302 over a special gunite reinforcing mesh 7Ϊ. The wire rope strands 24 and 25 are also wrapped with a wire mesh 72 which serve as a base for the gunite material and is an additional reinforcement for the radial beams.

The roof framework 20' is next raised to a position near the top of the column 30. In such position, the elastic roof forming tendons or stringers 23 are of such length that the pitch of the roof is of the ratio of one foot to ten feet. The roof framework 20' has been raised to dispose the outer annular compression ring 21 sufficiently off the foundation 12 to provide the desired height of the exterior wall 40.

. At this time, means of tying down the outer annular ring 21 to the foundation 12 are provided. This may include suitable wall studding to which the annular ring 21 may be secured. In this instance, tie down cables 32 are used. ' The tie down cables 32 are secured to the foundation 12 by anchor bolts 33. The anchor bolts 33 are permanently embedded within the foundation 12. A turnbuckle 34, or the like, is provided for uniformly tuning the tie down cables 32 and for subsequently relieving the tie down tension which is to be imposed upon the roof framework 20'. This tension is relieved after the roof framework 20' has been covered with concrete and the concrete has obtained its initial set.

We are now ready to exert the tensioning force on the radial tendons or elastic members 23 which will subsequently serve as the stressing force within the concrete shell which will form the building roof 20.

The roof beam forming tendons or stringers 23 are best tensioned by having hydraulic jacks apply an upward force on the cradle support 31 to raise or elevate further the inner annular tensile ring 22. This is as shown in FIG. 7. After the wire rope strands 24 and 25, which form the roof tendons 23, are in their recommended tension, the cradle 31 is secured to the central column 30 by means of high tensile bolts. Additional post support 61 may be provided thereunder. The supports 61 may be welded to an angle iron base 62 that is secured to the central column 30 by bolts 63. The angle iron base is secured to the inner foundation 11 by anchor bolts 64 embedded therein.

The channel iron band 65 shown in FIG. 7 is used as the axis of the revolving closure panel for the exterior wall opening 50. This is described in one of my copending applications previously referred to.

FIGS. 2 and 3 diagrammatically illustrate the tensioning of the roof forming tendons 23. In FIG. 2 the length of the ties between the outer and inner annular rings 21 and 22 is designated “X.” This is the length of each of the sixty radial ties after they have been tuned and the roof framework 20' has been elevated. The only tensioning is the dead weight of the roof framework 20' itself. In FIG. 3, the length of the roof forming ties 23 is indicated as “X+” which denotes the additional length of the ties caused by the upward force applied to the inner annular ring 22 while the outer annular ring 21 is restrained by the tie down cables 32.

Upon completion of the tensioning of the roof forming ties 23, the roof framework 20' is ready to be covered by the lightweight concrete aggregate. This is preferably accomplished by the gunnal or gunite method. The concrete aggregate is applied to both the top and bottom sides of the reinforcing wire mesh to thoroughly encase the high tensile roof strands 24 and 25 therewithin. The wire rope strands 24 and 25 remain in tension until the roof covering concrete aggregate, which forms the inverted conical shaped roof shell 20, has reached its initial set and can withstand the compressive forces exerted by the release of the tension force. The tension in the cables is released by means of the turnbuckles 34 slacking off on the tie down cables 32, or by similar means. Upon such release, the cables, still under substantial tensile strain, will exert a compressive force radially on the concrete covering.

. θ

Referring to FIGS. 7 and 8, the concrete coverihg 0f the screen mesh 71 and of the reinforcing rods 35 forms the roof shell 80. The application of concrete to the underside of the wire mesh screen 71 and about the wire 5 mesh 73 wrapping the ties 23 forms both the underside of the roof shell 81 and the full length roof rafters 82. The inner concrete covering forms a finished interior for the roof structure. The channels 73, as mentioned, serve as forms for the underside of the rafters or beams 10 82. A peripheral band 75 about the compression ring 21 serves as a form for the periphery of the roof and, incidentally, may be used as a guide track for revolving scaffolding used in applying the concrete aggregate to the top side of the roof surface.

The rafters or beams 82 are integral with the roof structure and serve to counteract the negative loading of the roof 20 caused by high winds. Accordingly, they eliminate any possible chatter or vibration usually expected in long unsupported spans such as with the in20 verted conical shaped roof 20.

The thin shell exterior wall 40 is next constructed. If tie down cable 32 has been used, instead of special tie down studding, the tension in such cables is relieved and the cables are either removed or left to be embedded 25 in the wall. Wall forming studdings 90 are next erected. The wall studs 90 are provided at regular intervals between the annular ring 21 and the foundation 12. Such studding does not extend across the area designated for the opening 50. Wire reinforcing. mesh 91 and 92 is 30 secured to the inner and outer sides of the studding 90. A mixture of cement plaster is applied by either the conventional hand trowel or the gunnal method to complete the wall 40.

The exterior wall 40 may . include members 93 to 35 close any space between the roof structure 20 and the wall 40 and to compensate for varied expansion. It is to be understood that the exterior wall 40 provides no support for the roof structure except to prevent tipping due to uneven wind or snow loads thereon.

It will be appreciated that the prestressed roof structure disclosed has the decided advantage of using stock materials and requiring a minimum of heavy materials and/or prior shop fabrication. Furthermore, there is no material waste or labor cost involved in constructing 45 and stripping concrete forms. The prestressed wire ropes and wire mesh covering serve as a base for supporting and shaping the structure, while in its pliable state, and as reinforcement therefore after the concrete covering has hardened.

While a preferred embodiment of this invention has been described, it will be understood that other modifications and improvements may be made thereto. Such of these modifications and improvements as incorporate the principles of this invention are to be considered as 55 included in the hereinafter appended claims unless these claims by their language expressly state otherwise.