US1940402A - Singly curved shells for the construction of roofs - Google Patents

Description

Dec. 19, 1933. F. DISCHINGER ET AL SINGLY CURVED SHELLS FOR THE CONSTRUCTION OF ROOFS Filed April 25, 1932 Inventors Z r z Fig.

Att orne s.

Patented Dec. 19, 1933 UNITED STATES SINGLY CURVED SHELLS FOR- THE CONSTRUCTION OF ROOFS Franz Dischinger and Ulrich Finsterwalder,

Wiesbaden-Biebrich, Germany,

assignors to the firm Carl Zeiss, Jena, Germany Application April 25, 1932,- Serial No. 607,390, and in Germany May 5, 1930 7 Claims.

This invention relates to the use and construction of shell roofs consisting of thin curved slabs, plates, or other members, in which-the roof acts as a structure of unified bending action, carrying the loads to widely spaced columns or other supports. The shell is singly curved.

In contrast to constructions of former days, in which singly curved roofs had supporting capacity only in the direction of the arch, a carrying action in the direction of the generating line of an arched shell, between widely spaced stiffening supports, is attained by the features of the present invention.

It is, for instance, possible to construct a barrel shell roof of 2 inch thickness and 45 foot arch width, without supports, over a span length of 150 feet or more in the direction of the generating line, if the shell, suitably stiffened by widely spaced stiffening members, such as trusses, diaphragms or marginal members, is reinforced by an arrangement of bars which, by their tensile action, hold the roof rigid and perform the carrying action in the direction of the generating line.

We illustrate our invention more or less diagrammatically in the accompanying drawing, wherein:

Figure 1 is a diagrammatic perspective view of one form of our invention;

Figure 2 is a perspective view showing a part of a singly curved concrete roof or shell;

Figure 3 is a section illustrating a roof formed of a plurality of singly curved shells or roofs such as that shown in Fig. 2.

Figure 4 is a perspective view of two singly curved roof shells combined to form a train shed; and

Figure 5 is a perspective view illustrating a combination of singly curved shell members forming a roof.

Like parts are indicated by like symbols throughout the drawing.

Figure 1 is a perspective view of a singly curved shell, a barrel-like vault a constructed of reinforced concrete between widely spaced transverse members b. Reinforcing bars 0 are anchored in the members b and extend from the members across the corners of the shell "0. to the longitudinal edge of the vault, thus conveying their stress to the reinforcement d adjacent the said edge. Bars 9 are provided in the direction of the arch, to counteract the deformation of the shell in its arched cross section.

Figure 2 shows a part of a single curved concrete roof consisting of a shell a, longitudinal edge reinforcement "d in the springing line of the shell, reinforcing bars g effecting a stifiening in the cross section of the arch, and diagonal tension rods 0. No supports are necessary along the said edge of the vaulted shell to take up any end thrust, because there is no end thrust in the shells of this invention, in marked contrast to arches used heretofore.

Roof shells such as are herein described will be chiefly subjected to direct stresses only. Flat curved roofs will be subjected to bending moments in the shell near points of discontinuity of the roof curve or of the loading, such as along skylights, or intersections with other roofs or bordering members. To prevent deformations of the slab by such moments, the transverse bending reinforcement of g is placed in the slab to stiffen it. The slab thus stiffened is able to carry loads in the direction of the generating line of the arched barrels if bars 0 are provided, anchored in stiffening members b, (see Fig. 1). By the described features a column spacing is rendered possible (viz: a distance between members b) of 150 feet or more.

The curved shell a may be combined with marginal members too slight to take lateral thrust, running in a longitudinal direction of the shell, which will act with the shell as one struc tural unit for bending action in the longitudinal direction, as shown at h h in Figure 3. These marginal members, of small width, are too weak to be able to take arch thrust from the shell a". Therefore, an arch action cannot take place. Instead, these members act with the shell as a structure of unified bending action. The arched shell will transform its carrying action into the action typical of the invention, if reinforcement and stiffening members b are provided as described, thus enabling extremely thin shell construction of wide spans.

Figure 3 shows a cross section through a combination of singly curved arched shells a connected consecutively. The longitudinal boundaries of the end vaults are connected or provided with marginal members h which may be either above, as at ha or below, as at hi" the springing lines of the arches. The valley line is between two arched shells is-stiffened by the combined action of the adjoining shells.

Figure 4 shows as an example the adaptation of the invention to train platform sheds. Two shell segments a, inclined to each other and connected with each other in the intersection line, are spanned between stiffening members b, which here are constructed as diaphragms above the shell slab. The shells are provided with small marginal beams n running in the longitudinal direction at the outer edges of the system. Bars 9 are provided in the direction of the arch, diagonal bars 0 near the corners of the shell are anchored in the diaphragm b. dinal reinforcement d is placed in the intersection line m" of the shells and in the marginal The longitubeams n. The roof may cantilever a certain 3 distance 9 beyond the diaphragm. Diaphragms b are supported by columns 11.

Heretofore a train shed roof of reinforced concrete would have to be built with purlins or heavy edge beams or ties. Continuous supports were necessary along the springing of the arched roofs to take the thrust of the arch. In this invention the main carrying action is in the longitudinal direction. In the case of a train shed made according to this invention there is no thrust at all in the outer edge line of the arched shell near the marginal beams, as these beams are much too weak to take any thrust from an arch. This fea ture of the present invention is, of course, in marked contrast to the action of an arched struc ture as used heretofore. The wider the arched slab the larger is the effectively contributing width of the shell as a contributing flange for the beam action in the longitudinal direction of the roof. Roofs of wide arch span are, therefore, more economical than roofs with small arch spans. This is another outstanding feature of the new invention. Whereas we describe this action as a beam action, it will be understood that we wish this to be taken as an analogy, rather than as a specific statement of the nature of the stresses involved. In fact, the problem of stresses in this case is a complex three-dimensional one, as in a dome. Connecting slabs are statically undetermined structures and have to be treated according to the rules and the theory of elasticity as found in any text-book on higher mechanics.

Figure 5 shows an adaptation of the invention for the construction of roofs for factories, shops, etc. The curved shell 0. is used between stiffening members 2) and provided with small marginal members 11., into which longitudinal reinforcing d is placed. Bars g in the direction of the arch and inclined bars 0 are provided, the latter anchored in the stiffening members as described before.

Whereas the shell as described will usually be made of concrete, the invention may also be applied to or carried out with other materials. The invention is not limited to the construction of roofs but can be applied to and used for various other types of structures such as, for instance, bridges, hanging shells, flumes, bins, tanks, etc. The special provisions concerning stiffening and reinforcing, according to the present invention, will always enable a singly curved shell to carry loads perpendicularly to the arch direction.

Depending on structural and economical considerations, a transverse stiffening member b may be constructed as a truss, a diaphragm, a beam, an arch, or any other suitable frame construction. 1

It will be realized that whereas we have herewith shown and described a practical operative device, nevertheless many changes might be made in the size, shape,, number and disposition of parts without departing from the spirit of the invention and we wish, therefore, that our showing be taken as in a sense diagrammatic.

We wish the term longitudinal edge to include the intersection between adjacent shells, as shown in Figures 3 and 4.

We claim:

1. In combination, a singly curved shell and a plurality of longitudinally spaced transverse stiffening members connected thereto and forming a unitary structure therewith, and reinforcing for relation to the transverse stiffening members, and

extending across corners of the shell to its longitudinal edge.

2. In combination, a singly curved shell and a plurality of longitudinally spaced transverse stiffening members connected thereto and forming a unitary structure therewith, and reinforcing for said structure, comprising members anchored in relation to the transverse stiffening members, and extending across corners of the shell to its longitudinal edge, and longitudinal reinforcing tension members extending approximately along the longitudinal edge of the shell.

3. In combination, a relatively flat singly curved shell and a plurality of longitudinally spaced transverse stiffening members connected thereto and forming a unitary structure therewith, and reinforcing for said structure, comprising members anchored in relation to the transverse stiifening members, and extending across corners of the shell to its longitudinal edge, and marginal members positioned along such longitudinal edge adapted to act with the shell as a structural unit of bending resistance between points of support of the shell.

4. In combination, a singly curved shell and a plurality of longitudinally spaced transverse stiffening members connected thereto and forming a ,unitary structure therewith, and reinforcing for said structure, comprising members anchored in relation to the transverse stiffening members, and extending across corners of the shell to its longitudinal edge, and other reinforcing members within the shell, positioned in the direction of curvature of the shell and adapted to counteract the deformation of the shell in its curved cross section.

5. In combination, a singly curved shell and a plurality of longitudinally spaced transverse stiffening members connected thereto and forming a unitary structure therewith, reinforcing for said structure, comprising members anchored in relation to the transverse stiffening members, and extending across corners of the shell to its longitudinal edge, and one or more adjacent singly curved shells forming a unitary structure with the first mentioned shell.

6. In combination, a singly curved shell and a plurality of longitudinally spaced transverse stiff ening members connected thereto and forming a unitary structure therewith, reinforcing for said structure, comprising members anchored in relation to the transverse stiffening members, and extending across corners of the shell toits longitudinal edge, and longitudinal tension reinforcing means 'along the longitudinal edge of the shell, and an additional longitudinal marginal member adapted, with the shell, to act as a structural unit of unified bending action between points of support of the shell.

7. A structure comprising a singly curved shell, constructed of reinforced concrete, in combination with longitudinally spaced transverse stiffening members, such structure having a longitudinal carrying action along the direction of the generating line of the arched shell, said stifiening members having associated therewith reinforcing means, anchored to the stiffening members and extending within the shell across the corners of the shell to the longitudinal edge thereof, and additional reinforcement extending longitudinal- 1y along the shell adjacent its longitudinal edge.

FRANZ DISCHINGER. ULRICH FINSTERl/VALDER.

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