US2388701A - Method and apparatus for constructing shell-form structures - Google Patents

Description

Nov. 13,1945, wqNEl-F METHOD AND APPARATUS FOR CONSTRUCTING SHEEL-FORM STRUCTURES Filed July 15, 1942 2Q I E Patented Nov. 13, 1945 METHOD AND APPARATUS FOR CON- STRUCTING SHELL-FORM STRUC- TURES Wallace Neff, Los Angeles, Calif.

Application July 15, 1942, Serial No. 451,056

18 Claims. (Cl. 25-1315) This invention relates to improvements in building construction, and more particularly to a method of constructing shell-form structures of concrete or like material by the use of an internal form only, and to an improved and simplied form for use in the practice thereof.

-The present invention contemplates and provides a method of building construction and a V novel form for use therewith which complements the 'improvements in building construction disclosed and claimed in my Patent No. 2,270,229, dated January 20, 1942, and application Serial No. 420,437, filed November 25, 1941, More speciiically, the present invention provides a form which is fabricated throughout of readily available materials and which can be inexpensively manufactured on a quantity basis. Moreover, the form according to the present invention is employed as the basis of a method of building construction which not only introduces substantial economies in constructing shell-form structures but is also extremely fast and its practice can be carried Vout with available, relatively unskilled labor.

Other objects `will be in part obvious and in part hereinafter pointed out in connection with the following analysis of this invention wherein is illustrated an vembodiment of the invention in detail.

In the drawing:

Fig. 1 is a perspective view of the improved form of the present invention;

Fig. 2 is a schematic transverse section taken through a structure erected by the method of the present invention;

Fig. 3 is a somewhat exaggerated sectional detail illustrating the preferred mode of securing the form to a suitable foundation and a typical lwall structure according to the invention.

Referring 'to the drawing, wherein like reference characters designate like parts throughout the several views, Fig. 1 is representative of the improved form according to the present invention which, for purpose of illustration, is shown as fully extended although it will be understood `that the form is normally collapsed and can be delivered to a site `in rolled or folded up condition. As shown, the form, which is generally designated lll, is in the nature of an open bottom shell and is preferably fabricated from a plurality of `triangular sectors ll secured along their adjacent edges so as to provide a shell-like or semi-spherical body devoid of a bottom.

According to the invention, which proceeds in part yfrom my discovery that lconcrete or plastic shell-form structures of size suitable for dwellings and industrial use, for example, can be erected upon pneumatic forms fabricated from readily available, flexible materials ofthe type which are' airproof or can be maintained airproof only at the relatively low inflation pressures measured in ounces per square inch, as distinguished from rubber coated and/or impregnated multi-ply canvas forms designed to sustain the relatively higher ination pressures of 2 to 5 lbs. per square inch, the pneumatic form as herein shown and contemplated is fabricated from readily available suitable materials such as the light-weight fabrics such as those successfully employed for parachutes, for example, nylon, ordinary cotton muslin having a high thread count such as aeroplane or balloon cloth of about 4 oz, material, and specially treated paper. Nylon is especially suitable because it can be supplied precoated and hence already airproofed, although the initial cost of forms fabricated therefrom is such that for economy in construction the forms should be capable of re-use. Cotton muslin is also a satisfactory material because of its availability and the cheapness of forms made therefrom and also because it can be readily airproofed. Treated paper of the type recently developed and successfully used for parachutes also provides a satisfactory form. In constructing the forms from nylon and muslin, the sections Il are cut from webs or pieces of the material and are thereupon secured together along adjacent edges preferably by sewing operation which can be performed on a conventional sewing machine. Substantially the same method of fabricating may be followed for forms made of paper, it being understood that means for securing the paper sections along their adjacent edges other than `sewing or in supplement of sewing may be employed.

The edge along the open bottom of the form is preferably re-inforced by a band or strip I2 secured against exterior of the sections Il as by sewing. The strip can be of the same material from which the vsections are formed, or of a different material selected for its reinforcement properties, and is of the order of 8" in height for a form having a 30 ft. diameter at its open bottom. As shown, one of the sections is provided with a nipple -|4 through which air under pressure is supplied to the interior of the form, although such is not necessary as air can be supplied to the interior of the form through one of the plumbing pipes or through an air pipe embedded in the foundation on which the form is stances can be employed, one such substance being available on the market under the name of Fullers Prepared Paint, such material Ibeingy applied as by painting or spraying. Or the form or seams thereof can be suitably airproofed by spraying with asphalt. Such airprooflng substances form a coat on the external surface of the form, with the coating substance seeping in the interstices of thefabric (or into the seams) to 4render the same impervious to air at the low pressure employed in the following described method' of construction.

Considering now the building construction method employing a form fabricated and airproofed as aforesaid, a suitable foundation is first prepared, such comprising a floor slab I6 having `a marginal footing I'I, the upper surface of the latter being stepped below the upper surface of the floor slab to provide a Vertical shoulder I8 formed with an overhang I9 as indicated in Fig. 3. It will be understood that the vertical shoulder I8 and its overhang I9 is formed between th footing and floor slab in the laying thereof.

-The form is arranged in collapsed position on the foundation and its reinforced edge 'I2 is laid along the vertical shoulder I8 and its overhang, andjis set in a mastic 2D with which the shoulder is preferably surfaced and which functions to seal the joint between the lower edge of the form and the floor slab I 6. When so arranged, the equator of the form will be disposed somewhat below the horizontal surface of the floor slab.

Thereupon, the form is secured along its edge as by steel tapes 2 I, 22 which are wrapped around the reinforced edge of the form and are clinched tight against the shoulder as by a box bailer.

The lower tape 2l is disposed below the overhanging surface I9 and thus anchors the form ,against upward forces tending to raise the form from its foundation, whereas the upper tape 22 secured against the overhanging shoulder I9 .anchors the form against sideward spreading forces.

With the form anchored to the floor slab in such manner that the latter closes the open bottom thereof, air under pressure from any suit- ,able source is supplied to the interior of the now closed form, as through the inlet nipple I4, and the form is accordingly inflated and distends to substantially semi-spherical shape. I have found that an inflation pressure of about 2 oz. per square inch is sufficient to properly inflate the Aform and that the stated low pressure inflation, which is of course maintained during the setting of the plastic material placed thereover, enables the form to sustain the loads to which it is subjected, although it will be understood that inflation to higher pressures is permissible, depending on the mateial employed in the form and its airproofness.

To shield Ithe secured lower edge of the form from the plastic material placed thereon, as will be described, and thus permit the form after erection has been completed to be removed from the foundation for re-use, a removable guard strip 23 of veneer can be Wrapped on the outside of the tapes 2|, 22 as shown in Fig. 3.

With the form now set up and inflated, I thereupon apply to the external surface thereof a relatively thin coating layer of a fast-setting plastic material such as gypsum plaster, concrete, or one of the so-called plastics. Due to its lightness, and also to the fact that it sets up in approximately twenty minutes, and can be nailed into after setting, one material which has been found successful in actual use is U. S. Gypsum casting plaster, which can be applied as a thin surface layer over the from as `by troweling, although other methods of application may be employed, depending on the particular plastic material selected for use.

The form is plastered over to a depth of about one inch in a working down operation in which, by reference to my above-referred to application Serial No. 420,437, the plastic material is placed first on the top or upper third portion of the form whereby the load thereof in relation to the air pressure at which the form is maintained results in a controlled deformation of the form, according to which the form is flattened at its top or pole portion and bulged outwardly along its side portions, thus to lower the ceiling and provide increased head room along the side of the final shell-form structure. Following deformation of the form as aforesaid, the plastic material is applied against the outwardly bulged side wall portions of the form.

Due to its fast-,setting properties, the layer or coating of plastic material sets up in relatively short time on the form to provide a self-sustaining shell which may be regarded as a preliminary shell, If the form is to be taken out for re-use, as in the case of the more expensive nylon forms, it is deflated and the guard strip 23 is taken out to provide access to the secured lower edge of the form, whereupon the tapes 2|, 22 are cut and removed, and the lower edge of the form is peeled from the shoulder I3 of the oor slab. Or the cheaper muslin or paper forms may be left in the shell and used for their insulation value. By reference to Fig. 3, wherein the so formed preliminary shell is indicated at 25, the shell is shown as unfaced interiorly. However, it will be understood that an inner facing coat of plaster or equivalent plastic material may, if desired, be applied against the inner surface of the shell (or form) for interior finish purposes, or, where the preliminary-shell is formed of concrete, for a final structure intended for industrial use, for ex ample, an additional inner layer of concrete or plaster may be applied against or built upon the inner surface of the shell.

For a, structure intended for use as a dwelling, the preliminary shell is preferably covered with a blanketor layer 26 of insulation to a depth of about one inch, whichV can be applied according to any one of the conventional methods of applying insulation furnished in strip or roll form, or insulation of the type which is sprayed on to a surface,r such as Sprayoflake According to thepreferred construction method, particularly where the nal structure is to be used as a dwelling, an outer layer 2'I of con- Itis also within the purview of the invention to place the outer layer of concrete by the conventional troweling method. In either case, the preliminary shell provides a load sustaining backing for the so applied concrete which, upon setting, forms a secondary or outer shell completely enclosing the inner shell and forming therewith a `composite wall structure of great strength.

By reference to Fig. 3, the concrete forming the outer shell is placed to a greater depth adjacent the lower edge thereof to ll in the space resulting 'from the bulge or overhang incident to the deformation of the form as described, with the result that the outer surface of the outer concrete shell extends substantially vertically .from the footing l1.

placed against the form as described and suitably securedin proper position prior to placing of the plastic material forming the preliminary shell. This material is placed around the opening frames which are thereby permanently set into the structure in the operation of erecting the preliminary shell. Following setting of the shell and deflation of the form, the latter can be removed through the soformed opening; or, where the form is left in the shell, the form is cut away within the openings, th-us to provide access to the interior of the form and the preliminary shell formed thereon. It will be understood that the insulation and the outer shell is placed around the opening frames set in the preliminary shell.

While the pneumatic form has been illustrated and described as semi-spherical, as required for the construction of dome-like structures, it will be understood that other shaped forms may be employed, notably that form which in transverse section corresponds to a section taken through a semi-spherical form but which is elongated as required for the 'so-called barrel shell or barrel arch type structure. Obviously, lthe form can be fabricated to provide other shapes of structures such, for example, having a rectangular or square body portion and a roof made up of triangular areas merging into each other.

Without further analysis, it will be seen that the present invention provides an inexpensive form which can be made in quantity and an extremely fast method employing such a form for erecting shell-like structures of size and type suitable for use as air-raid shelters, dwellings, grain bins, storage tanks, barracks, powder magazines, and the like. Moreover, it will be appreciated that as both the form and the method as described employ readily available materials and that the method can be practiced by relatively unskilled labor, the invention lprovides a solution to problems arising in the building construction industry by reason of shortages in and freezing or' the so-called critical materials and in skilled labor.

As many changes could be made in carrying out the above constructions without departing from the scope of the invention, it is .intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim:

.1. The method of.. constructing shell-form vstructures which consists in securing a collapsed inflatable member which is open at its bottom, but 'which is adapted when its bottom is closed and upon inflation to assume a size and shape corresponding substantially to the interior of the intended structure, to a suitable foundation 'in such manner that the foundation closes the open bottom, inflating the member, and applying a covering layer of settable plastic material on to the exterior surface of the inflated member in such mannerv that the applied material will remain in place without the aid of an external form and will provide upon setting a self-sustaining shell.

2. The method of constructing shell-form structures which consists in securing a collapsed inflatable member which is open at its bottom, but which is adapted when its bottom is closed and upon inflation to assume a size and shape corresponding substantially to the interior of the intended structure, to a suitable foundation in such manner that the foundation closes the open bottom, inating the member, applying a relatively thin covering layer of settable plastic material on to the exterior surface of the inflated member in such manner that the applied material upon setting will provide a self-sustaining preliminary shell, and building up on the exterior of the so-formed shell a covering layer of concrete of desired thickness which on setting provides an outer concrete shell superimposed on the preliminary shell.

3. The method of constructing shell-form structures which consists in placing on a suitable support a collapsed inflatable member which L is open at its bottom but which is adapted when its Vbottom is closed and upon inflation thereof to assume a size and shape corresponding substantially to the interior of the intended structure, securing the member along its open bottom to said support in such manner that the support closes the open bottom, inflating the member, and applying a covering layer of a settable plastic material on to the exterior surface of the inflated member in such manner that the material upon setting provides a self-sustaining shell.

4. The method of constructing shell-form structures which consists in arranging on a suitable foundation having a vertical edge surface a collapsed inflatable member which is open at its bottom but which is adapted when its bottom is closed and upon inflation thereof to assume a size and'shape corresponding substantially to the interior of the intended structure, securing the body along its open bottom to said foundation in such manner as to effect a sealed joint between the bottom edge of the form and the vertical edge surface of the foundation, infiating the member, and applying a covering layer of settable plastic -material on to the exterior surface of the inflated member in such manner that thematerial upon setting provides a self-sustaining shell.

5. The method of constructing shell-form structures which consists in placing on a suitable supporta collapsed inflatable member which is open at its bottom but which i's adapted when its bottom is closed and upon inflation thereof to assume a size and shape corresponding substantially to the interior of the intended structure, securing the member along its open bottom to said support in such manner that the support closes the open bottom, infiating the member, applying a covering layer of a settable plastic material on to the exterior surface of .the inflated member in such manner that the material upon setting provides a self-sustaining preliminary shell, applying insulation to the exterior surface of the preliminary shell, and building up on the exterior of the insulated preliminary shell a covering layer of concrete of desired thickness which on setting provides an outer concrete shell superimposed on and insulated 'from the preliminary shell.

6. The method of constructing shell-form structures which consists in arranging on a suitable foundation having a vertical edge surface a collapsed inflatable member which is open at its bottom but which is adapted when its bottom is closed and upon inflation thereof to assume a size and shape corresponding substantially to the interior of the intended structure, securing the member along its open bottom to said foundation in such manner as to effect a sealed joint between the bottom edge of the member and the vertical edge surface of the foundation, inflating the member, applying a covering layer of settable plastic material on to the exterior surface of the inflated member in such manner that the material upon setting provides a self-sustaining preliminary shell, applying insulation to the exterior surface of the preliminary shell, and building up on the exterior of the insulated preliminary shell a covering layer of concrete of desired thickness which on setting provides an outer concrete shell superimposed on and insulated from the preliminary shell.

'7. The method of constructing shell-form structures, which consists in providing a form made from a light-Weight, flexible material which is airproof only at inflation pressures of substantially less than one lb. per square inch and of shape and size adapted upon being set up and inflated to correspond substantially to the interior of the structure, anchoring the form to a suitable foundation, inflating the form to a pressure not exceeding that at which the form material is airproof, appliyng a plastic material characterized both by its fast-setting properties and its lightness in weight as a continuous layer over the external surface of the form and to a layer thickness such that the load of the plastic material does not exceed the load sustainable by the inflated form and in such manner that the layer of plastic material will remain in position on the inflated form without the aid of an external form, and maintaining the inflation pressure within the form until the plastic material has set, whereby said material upon setting provides a self-sustaining preliminary shell against a surface of which concrete may be placed to desired thickness.

8. The method of constructing shell-form structures, which consists in securing to a suitable foundation a collapsed pneumatic form fabricated from flexible material which is airproo-f only at inflation pressures substantially below one lb. per square inch and which is of shape and size adapted upon inflation to correspond substantially to the interior of the intended structure, inllating the form to a pressure not exceeding the pressure at which the form material is airproof, applying a plastic material characterized by its fast setting properties and its, lightness in weight as a continuous layer over the external surface of the form and to a layer thickness such that the load of the plastic material does not exceed the load sustainable by the inflated form and in such manner that the'layer of plastic material will remain in position on the inflated form without the aid of an external form, and maintaining the inflation pressure within the form until the plastic material has set, whereby said material provides a self-sustaining preliminary shell against a surface of which concrete may be placed to desired thick- IleSS.

9. The method of constructing shell-form structures whichv consists in providing a form made from light-weight materials such as nylon, cotton muslin, treated paper and the like, and which is open at its bottom but which is adapted when its bottom is closed and upon inflation t0 assume a size and shape corresponding substantially to the interior of the intended structure, air-proofing the form along portions thereof requiring the same, anchoring the form to a suitable foundation in such manner that the foundation closes the open bottom of the form, inflating the form with air to a pressure of about 2 oz. per sq. in., and applying a fast-setting plastic material characterized by lightness in weight over the form and in such manner that the material will remain in position on the form Without the aid of an external form and upon setting will provide a self-sustaining preliminary shell to a surface of which concrete may be applied to desired thickness.

10. The method of constructing shell-form structures which consists in providing a form made from sections of light-Weight material such as nylon, cotton muslin and the like secured along adjacent edges, and which is open at its bottom but which is adapted when its bottom is closed and upon inflation to assume a size and shape corresponding substantially to the interior of the intended structure, airproofing the form at least along the secured edges of the sections making up the same, anchoring said form to a suitable foundation in such manner that the foundation closes the open bottom of the form, inating the form with air to a pressure of about 2 oz. per sq. in., and applying a fast-setting plastic material characterized by lightness in weight over the form and in such manner that the material will remain in position on the form without the aid of an external form and upon setting will provide a self-sustaining preliminan7 shell to a surface of which concrete may be applied to desired thickness.

11. The method of constructing shell-form structures which consists in placing on a suitable support a collapsed inflatable form which is open at its bottom but which is adapted when its bottom is closed and upon inflation thereof to assume a size and shape corresponding substantially to the interior of the intended structure, securing the form along its open bottom to said support in such manner that the support closes the open bottom, inating the form, applying a shielding strip along and exteriorly of the secured bottom of the form, applying a, covering layer of a settable plastic material on to the exterior Surface of the form and shielding strip in such manner that the material upon setting provides a self-sustaining shell, collapsing the form after the material has set, and detaching the form from the support and removing it from the shell.

12. The method of constructing shell-form structures which consists in arranging on a suitable foundation having a vertical edge a collapsed inflatableforinwhich is open at its bottom but which is adapted when its bottom is closed and upon inflation thereof to assume a size and shape corresponding substantially to the interior structure, securing the form along its open bottom to said foundation in such manner as to effect a sealed joint between the bottom edge of the form and the vertical edge surface of the foundation, inating the form, applying a shielding strip along and exteriorly of the sealed joint, applying a covering layer of a settable plastic material on to the exterior surface of the form and shielding strip in such manner that the material upon setting provides a self-sustaining shell, collapsing the form after the material has set, and

. detaching the form from the foundation and removing it from the shell.

13. A pneumatic form for use in the construction of shell-form structures of size and shape suitable for use as dwellings, shelters, and the like, consisting of an inatable shell fabricated from light-weight flexible material and being airproof only at inflation pressures which Vdo not substantially exceed two ounces per square inch, the shell being open at its bottom and being adapted for securement along its open bottom to a concrete foundation for the structure and which provides a bottom therefor.

14. A pneumatic form for use in the construction of shell-form structures of size and shape suitable for use as dwellings, shelters, and the like, consisting of an inflatable body fabricated from light-weight flexible material and being airproof only at inflation pressures of substantially less than one lb. per square inch, the body being provided along its bottom with means by which it can be secured to a concrete foundation.

15. A pneumatic form for use in the construction of shell-form structures of size and shape suitable for use as dwellings, shelters, and the like, consisting of an open-bottom inflatable shell fabricated from nylon and which carries a substance rendering said material airproof, the

fabric shell being adapted for securement along its open bottom to a concrete foundation for the structure and which provides a bottom therefor.

16. A pneumatic form for use in the construction of shell-form structures of size and shape suitable for use as dwellings, shelters, and the like, consisting of an open-bottom inatable shell fabricated from cotton musline and which carries a substance rendering said material airprcof, the fabric shell being adapted for securement along its open bottom to a fundation providing a bottom therefor.

17. A pneumatic form for use in the construction of shell-form structures of size and shape suitable for use as dwellings, shelters, and the like, consisting of an open-bottom iniiatable shell fabricated from paper and which carries a substance rendering said material airproof, the fabric shell being adapted for securement along its open bottom to a fundation providing a bottom therefor.

18. A pneumatic form for use in the construction of shell-form structures of size and shape suitable for use as dwellings, shelters, and the like, consisting of an open-bottom inatable shell fabricated from a plurality of sections of fabric material secured together along their adjacent edges, the material of said sections carrying a. substance rendering the same airproof and the form being additionally airproofed along the secured edges of the sections, and the form being adapted for securement along its open bottom to a concrete foundation for the structure and which provides a bottom therefor.

WALLACE NEFF.

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