US2536174A - Roof structure and the like - Google Patents

Description

Jan. 2, 1951 w, HAMILTON 2,536,174

ROOF STRUCTURE AND THE LIKE Filed April 29, 1947 1 2 Sheets-Sheet 1 Fig.1.

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Jan. 2, 1951 w. HAMILTON ROOF STRUCTURE AND THE LIKE 2 Sheets-Sheet 2 Filed April 29, 1947 Inn E1171 wbzazm W ma G6,

carried on said ribs.

Patented Jan. 2, 1951 UNITED STATES PATENT OFFICE Application April 29, 1947, Serial No. 744,545

' In Great Britain March 25, 1947 3 Claims.

This invention relates to roof structures and the like and has for its object to provide an improved construction of domed roof or the like suitable for use on storage tanks, gasometers, buildings and other structures; the particular object of the invention is to provide a structure which is simple in construction and erection and can be made of light Weight.

' According to this invention a domed structure comprises a substantially circular base-ring, a set of arched ribs arranged substantially parallel with one another extending chordwise across the base-ring, a second set of arched ribs also substantially parallel with one another arranged transversely to the first set and extending chordwise across the base-ring, and plating Preferably the curvature of all the ribs is the same, thereby simplifying their fabrication, and

.for a very flat or shallow dome whereof the curvature is small, the ribs may be arched or curved to a circular shape.

According to another feature of this invention, the ribs are halved into one another so as all to lie in the same spherical surface and facilitate the mounting of the roof-plates thereon.

According to yet another feature of the invention, the ribs are made in the form of rectangular box girders which may be of aluminium or a light alloy metal, and they may be held together at their junctions by a simple fastening, such as a rivet, extending through two crossing ribs thereby locking them together against movement in any direction.

In the accompanying drawings,

Figure l is a diagrammatic plan view of a domed structure prior to the application of the plating thereto,

Figure 2 is a section on the line 2-2 of Figure 1,

Figure 3 is a view similar to Figure 1 of a slightly modified arrangement, and

Figure 4 is a sectional view to a much larger scale of a detail of the construction.

The constructions illustrated in the accompanying drawings are applied to a domed roof for a cylindrical oil-storage tank in which the pitch of the roof, i. e. the maximum height of the dome above its base, is very small compared with its diameter. The invention is of particular advantage in the case of large tanks of the order, say, of 100 feet or so in diameter although of course it can be applied to tanks of any desired size. As is indicated in Figure 2, the

height of the dome is of the order of of the diameter.

The roof structure according to this invention may be applied to any cylindrical tank, and in Figure 4 the reference It) indicates the upper edge of the vertical wall of such a tank. Two strengthening plates ll, l2 may be secured to the upper edged the wall 10 to stiffen and strengthen it being secured by welding or any other convenient manner. A steel ring which is preferably of angle section as indicated at I3, i4 is also secured to the upper edge of the wall of the tank and-stiffening plates, and this ring constitutes the main support for the domed roof. The roof structure as illustrated in Figure 1 is constituted by two sets of arched ribs whichextend chordwise across the ring I4 and are supported on it. One set indicated at I5 is arranged parallel or substantially parallel with one another at a uniform spacing, say for example 6 feet apart, and they are all made of the same curvature; when the curvature is small, that is to say when the radius of curvature is large, they are arched to a circular form as determined by the arch which extends diametrically across the ring hi on the section line 2-2 of Figure 1. Since all the individual ribs are of the same curvature it is necessary only to cut them to appropriate lengths to be supported chordwise on the base ring l4. An exactly similar set of ribs l6 isarranged transversely to the first set, at right-angles thereto, and they are preferably spaced apart similarly to the first set of ribs thereby providing a structure having square openings l'l defined by the two sets of ribs.

The ribs are preferably made of aluminium, or a light alloy in the form of rectangular box girders as shown at is in Figure 4, and where a rib of one set crosses a rib of the second set. they are halved into one another as shown at IS in Figure 4 so that the upper surfaces of all the ribs lie in the same uniiormlycurved surface. The plating 2B is secured in any convenient manner to the upper surfaces of the ribs as for example by welding or any other convenient means. The plates can be comparatively thin, since it is convenient that each plate should cover one opening I! as shown in Figure 1, that is to say it is about 6 feet square. This gives a size and Weight of plate which, in a light alloy, can be conveniently handled.

Where two ribs intersect, one another as shown at l9, they may if desired be secured together by a rivet 2| or other simple fastening thereby ensuring a perfectly rigid joint. In

some instances, however, this fastening may be omitted since the ribs are all of arched form subject only to a compression loading.

Each rib is secured to the base-ring i l by means of a solid filling piece 22 on the end to receive a screw-threaded member 23 provided with a spherically shaped head 24 received in a similarly shaped socket 25 in a bracket 26 which rests on thebase-ring M as shown in Figure 4. .The bracket 25 may be bolted or otherwise secured to the base-ring I4 if so desired. The head 24 of the screw-threaded member 23 may be retained in its socket by a cover-plate 21 if so desired.

When the height of the dome is Very small compared with its diameter, the surface defined by the upper surfaces of the ribs l and it as shown in Figure l is a very close approximation to a spherical surface and the uniform spacing and curvature of the ribs as above described thereby simplifies the fabrication of the structure.

Figure 3 illustrates a slight modification in which the two sets of ribs 28 and 29 are all arranged. as great circles on the spherical surface of the dome, since this arrangement in some casesproves the strength of the structure. As will be appreciated, however, the intersections of the various crossing ribs are not all exactly at rightangles to one another and if a close fit of the crossing ribs where they are halved together is required individual machining may be re- .quired at each intersection.

It also lies within the scope of this invention to use other shapes of curvature, such for example as a parabolic curve which however in the case of a flat dome approximates very closely to a spherical curvature so that although the parabolic curvature is theoretically more accurate the spherical curvature first described is possible .gfrom a practical point of view.

that the maximum economy of material is obtained. By using aluminium or light alloys, the weight of the components of the structure is very substantially reduced so that the transport and erection is considerably facilitated. Moreover the only machining operation required on the ribs is a simple milling to enable them to be interlocked with one another, and this can, if desired, be effected on the site so that no prefabrication of the structural elements is required.

' The reduction in weight which is obtainable 4 by the use of aluminium or light alloys and by the particular construction above described is also advantageous in reducing the necessary strength for the side walls or supports of the roof, and the foundations. In the case of oil storage tanks the use of aluminium is particularly advantageous in that it is less subject to corrosion and the maintenance costs are substantially reduced; thus, for example, inthe case of a steel tank painting of all the exposed parts is required at frequent intervals whereas with aluminium and light alloys, only an initial painting is necessary. The use of light alloys moreover renders it unnecessary to use particularly small sections to achieve a reduction in weight, so that any corrosion which does take place is much less serious.

Whilst the simple arrangement of halving the ribs into one another as above described is the preferred one, it is not essential since the two sets of ribs could lie in superposed planes, being secured together at their crossingv points by any convenient means and the roof plates would then be supported on the upper set of, ribs.

Whilst such constructions may be used in particular cases, they will not usually be as desirable as the construction above described.

I claim:

1. A domed roof structure comprising a, circular base-ring, a set of arched ribs extending across parallel chords of the base-ring, a second set of arched ribs arranged across parallel chords of the base-ring transversely to the first. set and extending proximately to said first set to intersect therewith, each rib of each set extending continuously across each intersection with a rib of the other set, members having spherically shaped heads secured to the ends of the ribs, sockets secured to the base-ring to receive the spherically shaped heads of said members.

2. A domed roof structure according to claim 1 wherein said members having spherically shaped heads are each provided with a screw-thread arranged to engage a corresponding thread on the rib.

3. A domed roof structure according to claim 1 in which each rib of the first set is rigidly secured to each rib of the second set which it intersects.

WILLIAM HAMILTON.

REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Number Country Date.

285,022 Great Britain 1929 671,873 France 1929 774,204 France 1934

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