US3452494A

US3452494A - Multicurved building structure

Info

Publication number: US3452494A
Application number: US593995A
Authority: US
Inventors: Hector Thomas Prior
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-11-22
Filing date: 1966-11-14
Publication date: 1969-07-01
Anticipated expiration: 1986-07-01
Also published as: GB1108238A

Description

M a, 1969 H. T. PRIOR 3,452,494

MULTICURVED BUILDING STRUCTURE Filed Nov. 14, 1966 12 6712 5 67125 W mm MMIZL ,4 TTOANEV.

United States Patent U.S. CI. 5280 6 Claims ABSTRACT OF THE DISCLOSURE A multicurved grid structure including a plurality of mutually spaced regions of intersection, and first and second sets of transversely extending members connecting said regions of intersection, respectively. The members have such a configuration that the members of at least one set are deformed in an accordion manner upon bending of the grid structure to a curved configuration.

This invention relates to multicurved structures.

Multicurved structures, for example domed structures, may be constructed by curving the individual members separately and then assembling such curved members together into a structure having the required shape. Such a procedure has the disadvantages that a number of forming or bending operations have to be performed, one for each member to be curved, and that the pre-curved members must then be accurately located relative to one another prior to being secured together, such operation being time consuming.

The invention has for an object to provide a structure which can be shaped as a whole into the required curvature, that is to say the individual members of the structure are not individually curved but are given the required final shape when in company with all the other members making up the structure. The invention thus simplifies the construction of multicurved structures by obviating individual curving operations and the relatively complicated assembly procedure attendant upon individually precurved members.

The problem in constructing a structure capable of being bent into multi-curvature may be illustrated by considering the case of a flat sheet. If the sheet is first bent in one direction to have a tunnel-like shape then it is practically impossible to thereafter bend the already curved sheet so as to form it into a dome. The reason for this is that the initial bending operation stifiens the sheet to an extent such that the sheet resists subsequent bending la a direction transverse of the initial bending operation. Even when the two bending operations are carried out simultaneously, the same difiiculty is experienced since the sheet exhibits an ever-increasing stifiness as its curvature in increased in either of the two bending directions and consequential ever-increasing resistance to such bending.

The invention provides a structure which may readily be bent into multi-curvature, such structure being so constructed that when subjected as a complete entity to bending in directions transverse of one another, the structure will bend in one of the two directions substantially independently of the bending in the other direction.

To this end, the invention comprises a grid structure for forming a multicurved structure, comprising a grid having a pair of sets of members, the members of each set running in generally the same direction, and the sets running transversely of one another, at least the members of one of the sets being bent out of the general plane of the grid such as to be capable of flexure and permit bending of the grid in a direction elfecting such fiexure with- 3,452,494 Patented July I, 1969 out attendant curving of the members of the other of the sets.

The invention can probably be best understood by considering a simple example. The example comprises a flat square sheet with a central square aperture forming two pairs of opposite side members. Each member of one of the pairs is bent downwardly out of the plane of the sheet so as to comprise two straight legs at an angle to the other pair of members and joined to each other at their lowermost end along a line of bending; the upper end of each such member is joined to the respective member of the other pair also along a line of bending. Such a sheet may readily be bent so as to curve the planar members, and when thereafter or simultaneously bent to curve the bent members, those members will flex about their various lines of bending and their legs will open out or close together as the case may be in accordion fashion so that whilst the members generally conform to the desired curve, their act of bending does not result in multicurving the previously curved planar members.

Preferably, the planar members are also bent, so that both sets of members will be pleated and flex in accordion fashion when the sheet is subjected to complex bending.

In order to further facilitate an understanding of the invention there will now be described some embodiments thereof, given by way of example only, reference being had to the accompanying drawings, in which:

FIGURE 1 is a plan view of a grid embodying the invention;

FIGURES 2 and 3 are side and end elevations of the same grid;

FIGURE 4 is a side elevation of a pair of such grids connected together to form a double grid structure;

FIGURE 5 is a side elevation also of a pair of such grids connected together to form an alternative grid structure;

FIGURES 6 and 7 are a plan view and a side elevation respectively of a balloon support intended to act as a former for such grids; and

FIGURE 8 is a detailed cross-sectional view of the reinforced dome-shaped structure taken along line 88 of FIG. 6.

IN FIGURES 1 to 5, the broken lines denote lines of bending.

Referring first to FIGURE 1, a sheet of material 1 is formed into a grid by a plurality of apertures 2 so that the sheet is defined, as viewed in that figure, into parallel lines of horizontal members 3 and parallel lines of vertical members 4 making up two sets of such members, one set being transverse of the other. The horizontal and

vertical members

3 and 4 respectively have regions of intersection 5. Each member 3 is bent out of the general plane of the sheet and comprises two

straight legs

6 and 7 joined to one another along a line of bending 8 and to the respective intersection regions 5 by lines of bending 9 and 10 respectively. Similarly, each member 4 is bent out of the general plane of the sheet and comprises two

straight legs

11 and 12 joined to one another along a line of bending 13 and to the respective intersection regions 5 by lines of bending 14 and 15 respectively.

When the sheet 1 of FIGURE 1 is bent downwardly out of the plane of the drawing, say, about a vertical axis as viewed in FIGURE 2, the individual members 3 are not curved as such, but instead their

legs

6 and 7 flex about their respective lines of bending 8, 9 and 8, 10, and move closer together with the eii'ect that the lines of vertical members 4 are tilted with respect to one another, so that line PQ will generally conform to a curve. Similarly, when the sheet is likewise bent downwardly, but about a horizontal axis as viewed in FIGURE 3, the

individual members 4 are not actually curved, but rather their

legs

11 and 12 flex about their respective lines of bending 13, 14 and 13, 15, and move towards one another so that the lines of horizontal members 3 are tilted with respect to one another and the line RS will generally conform to a curve. The flexure of the

members

3 and 4 may be likened to that of the pleats of an accordion.

The sheet of material can thus be bent so that PQ is curved and RS is simultaneously and independently curved. Accordingly, domes or more complex shapes are able to be formed.

The grid need not be formed from sheet material. For example, an array of strips or rods, appropriately bent and joined in the intersection regions could be used. The sheet material would usually be of metal, but other materials, such as synthetic plastics, could be adopted depending on the strength required of the structure.

The grid when bent would form a stable structure providing that its material in the regions of the various lines of bending was deformed past the elastic limit during the bending process. As such, the multicurved grid could be used by itself, and form for example a domed roof. It is, however, envisaged that the grid would comprise a tensile reinforcement embedded in a settable material, such as concrete, having strength in compression. In such use, the material of the grid need not be stressed during bending past its elastic limit since when the concrete, for example, sets around the curved grid, the grid would be locked in the desired multicurved condition.

Referring now to FIGURE 4, the double grid structure shown therein comprises two grids, constructed as illustrated in FIGURES 1 to 3, fastened together in the intersection regions 5. Cavities 16 are thus defined between the opposing pairs of

legs

6, 7 of the two grids, and also, although not shown, between opposing pairs of

legs

11, 12. When embedded in a settable material, such material will fill those cavities 16 so as to rigidify the grids and firmly lock them in the final curved shape.

It FIGURE 5, the two grid sheets 1 are secured to one another along the lines of bending 8 and 13. Again, settable material filling cavities between the two grid layers will lock the grid structure firmly in final form.

The grids may be joined in any suitable manner. Preferably, the joining would permit the grids to make a limited degree of movement relative to one another during the bending process. Thus, rivet joining using slightly over-sized rivet holes could be adopted. However, rigid joins could also be utilized.

It will be appreciated that the discussed bending properties of a single grid are retained in the described doublegrid structures, and, moreover, that more than two grid layers could be successfully adopted.

Apertures additional to the apertures 2 of FIGURE 1 could be provided to control the bending properties, to

facilitate filling the cavities between the grids, or to give i access for tools for joining purposes if there were more than two grid layers.

Referring now to FIGURES 6 and 7, there is shown a balloon 17 of generally hemi-spherical form which is constrained by flexible members 18, having strength in compression, running radially from the middle of the balloon top to its edges, to take up a corrugated shape. The restraining members could be temporary or could form part of the final structure to be formed on the bal- Icon.

The balloon would be used with any of the described grid structures to form such structures, which Would be suitably applied to the balloon surface, into the required curvature. When the grid structures have been shaped, the balloon would be removed.

When the grid structures are to comprise a tensile reinforcement in, say, concrete, they would be slightly spaced by any suitable means from the balloon surface so that the concrete when applied to the balloon would completely cover or encapsulate the grid and not leave any parts thereof exposed to view in the final structure.

By using more complex systems of constraining members, more complex shapes could be produced. The restraining members need not be confined to the outer surface of the balloon but could also be inside.

I claim:

1. Grid means for forming a multicurved structure, comprising (1) a pair of unitary grids each including (a) a plurality of mutually-spaced generally co' planar regions of intersection, and

(b) means connecting said regions comprising a plurality of parallel spaced first V-shaped connecting members each connected between a pair of said regions, respectively, and a plurality of parallel spaced second V-shaped connecting members extending orthogonally to said first members and each connected between a pair of said regions, respectively, each of said first and second connecting members defining on a given side of the plane of said regions of intersection a pair of converging legs joined by a line of bending;

(c) said grids being arranged in reversed opposed relation; and

(2) means connecting portions of one grid with corresponding portions of the other grid to define a composite grid structure.

2. Grid means as defined in claim 1, wherein said grids are arranged with said regions of intersection adjacent and opposite each other;

and further wherein said regions of intersection constitute those portions of the two grids that are connected together to define the composite grid strucure.

3. Grid means as defined in claim 1, wherein said grids are arranged with said lines of bending adjacent and opposite each other;

and further wherein said lines of bending constitute those portions of the two grids that are connected together to define the composite grid structure.

4. A generally dome-type reinforced structure, comprising support means including a plurality of spaced vertical flexible members supported at their lower ends by a fixed support, said members converging upwardly for mutual connection at their upper ends to define a dome-shaped support; grid means including a pair of unitary grids each including a plurality of mutually spaced generally coplanar regions of intersection, and means connecting said regions comprising a plurality of parallel spaced first V-shaped connecting members each connected between a pair of said regions, respectively, and a plurality of parallel spaced second V-shaped connecting members extending orthogonally to said first members and each connected between a pair of said regions, respectively, each of said first and second connecting members defining on a given side of the plane of said regions of intersection a pair of converging legs joined by a line of bending, said grids being arranged in reversed opposed relation, and means connecting portions of one grid with corresponding portions of the other grid to define a composite grid structure, said composite grid structure being supported by said support to define a curved configuration in which at least some of said first and second connecting members are bent in accordion fashion about said lines of bending;

and a layer of settable material covering the unitary grid means, said grid means being embedded in said settable layer.

5. A structure as defined in claim 4, wherein the port'lons of said grids that are connected together to define .5 6 the composite grid structure are the regions of inter- 557,625 5/1923 France. section. 737,140 6/ 1953 Great Britain. 6. A structrue as defined in claim 4, wherein the por- 1,032,117 3/1963 Great Britain.

tions of said grids that are connected together to define the composite grid structure are the lines of bending. 5 FRANK L. ABBOTT, Primary Examiner.

References Cited S. D. BURKE, Assistant Examiner. UNITED STATES PATENTS Us Cl- XRu 3,118,186 1/1964 Moss 5282 FOREIGN PATENTS 1Q 52-2, 340, 414, 622, 674

221,393 4/1910 Germany.