US2966242A - Light steel girder - Google Patents

Description

Dec. 27, 1960 w. KAISER LIGHT STEEL GIRDER Filed Sept. 17. 1957 INVENTOR WILL) kfl/Sff BY J21 iQ/fiwg United States Patent C) LIGHT STEEL GIRDER Willy Kaiser, 1S Myliusstrasse, Frankfurt am Main, Germany Filed Sept. 17, 1957, Ser. No. 684,461

Claims priority, application Germany Sept. 18, 1956 1 Claim. (Cl. 189-37) The present invention relates, in general, to ferroconcrete ribbed ceilings and, in particular, light steel girders for such ceilings.

In forming ferroconcrete ribbed ceilings, it is a generally accepted practice to use light steel girders provided with a lower boom which serves as a support for the ceiling bricks or shuttering panels.

The lower boom, in addition, constitutes the tension reinforcement for the ribs of the finished ceiling after the usually in situ-mixed concrete has been formed or cast about the ceiling girder. Many different types of such light steel girders are known in the prior art. These girders are supplied in standard sizes, the cross-section of the rods, and the metal plates, or the like, which form the lower booms of the girders are so dimensioned as to provide the necessary strength to take up the usual stresses which normally occur in multi-storied structures or buildings.

The primary aim and object of the present invention is to provide means conducive to a girder structure, which ensures a much better acceptance of the thrust forces between the lower boom of the girder and the concrete of the ceiling than was possible with the girders of the prior art.

Another object of the present invention is the provision of means affording a novel girder structure, which allows for a relatively simple mode for suspending the rib and bay shutterings from the girder.

Another object of the present invention is the provision of a girder having a highly efficient lower boom arrangement or construction which is connected to the web of the girder in a relatively simple manner.

A further object of the present invention is the provision of a highly efiicacious support carrier construction provided on the girder which is formed so as to extend beyond the lower boom a required distance for covering by the concrete.,

A still further object of the present invention is the provision of a generally improved steel girder of the described type which is relatively simple to manufacture and which is easy and eflicient in use.

In accordance with the present invention, the lower boom of the girder is constituted by two or more tension rods disposed in parallel relation and maintained in relative spaced relation by transverse bars or rods. These transverse rods are securely fixed to the parallel rods, the web of the girder being secured also to said transverse rods. Support carriers are suspended from the transverse bars and extend below the tension rods by the amount or distance necessary or required for the covering thereof by the concrete.

The support carriers are constituted by stirrup bands which are secured to and supported by the transverse rods. Said support carriers accommodate shuttering battens which correspond to the width of the ceiling ribs and which serve as supports for the ceiling plaster. The transverse rods are bent over the tension rods and extend downwardly therefrom and, at the free ends thereof, said transverse rods carry or mount the stirrup bands provided with the shuttering battens.

The above and other objects, features and advantages of the present invention will be more fully understood from the following description considered in connection with the accompanying illustrative drawings.

In the drawings which illustrate the best modes now contemplated for carrying out the invention:

Fig. 1 is a side elevation view of a girder pursuant to the present invention;

Fig. 2 is an end view of the girder illustrated in Fig. 1;

Fig. 3 is a view similar to Fig. 2, on a larger scale, of a node point, with a support carrier provided on the girder;

Fig. 4 is a sectional view taken on the line IVIV of Fig. 3;

Fig. 5 is a sectional view similar to Fig. 4 and illustrates another embodiment of the invention;

Fig. 6 is an end view of the node point in the embodiment of Fig. 5, with the support carrier omitted;

Fig. 7 is a side elevation of a node point of the girder pursuant to an additional embodiment of the invention; and

Fig. 8 is an end view of the embodiment shown in Fig. 7.

Referring now to Figs. 1 through 4 of the drawings in detail, there is shown a light steel girder pursuant to the present invention. Said girder is provided with a lower boom comprised by the two tension rods 1 and 2 which are retained in parallel relation by the trans-- verse rods or bars 3 suitably secured thereto, preferably by welding. The bars 3 are provided at spaced points longitudinally of the rods 1 and 2, as best illustrated in Fig. 1. The girder is provided with an upper boom 11 which extends longitudinally thereof in parallel relation to the lower boom and spaced upwardly of the latter.

The upper and lower booms of the girder are separated by a web formed by a pair of steel bands '4 and 9 each of which extend longitudinally of the girder in zig-zag or serpentine fashion. The lower band 4 is guided about the transverse spacing rods 3, as best shown in Fig. 1, being suitably secured or fixed thereto, preferably by welding. The upper band has a conformation which is in opposition to the conformation of the lower band and is secured to the lower band, preferably by welding, at the abutting bend points 10 of said bands. The upper boom 11 is suitably secured to the upper band 9 at the non-abutting bend points thereof, as shown in Fig. 1.

It will be noted that the provision of the two tension rods 1 and 2 results in or provides a greater adhesion or supporting surface than is possible where only one tension rod is provided which single rod has the same tensile strength as both of said rods 1 and 2. In addition, the transverse rods 3 can take up the thrust forces which are produced between the concrete and the tension rods 1 and 2 after the concrete has been cast or formed about the girder.

As best shown in Figs. 3 and 4, each alternate transverse bar or rod 3 is provided with a pair of extensions 3a which are bent downwardly about the tension rods 1 and 2. A channel-shaped stirrup band 6 is suitably secured to or carried by the free ends of each pair of extensions 3a. As best shown in Fig. 3, said free ends are beaded-over or riveted to the stirrup band. It will be understood that said stirrup bands may, if desired, be secured to others of the transverse rods than the alternate or second transverse rods.

In the illustrated embodiment, the bands 6 mount a Patented Dec. 27, 1960 wooden batten. 8 which can serve as a plaster support in the finished ceiling.

The batten 8 serves as support for clamping straps 12 of 'tro'n'gh shaped bay shutterings .13. .These bay shuttering'smay also be supported directly on'the-batten 8; The illustrated sheet-metal shutterings 13 are removed after the site-mixed concrete has set. In place: thereof, it is also possible to place stones or slabs on the batten 8 to serve as shuttering, such stones or slabs remaining in the finished ceiling.

It is an important feature of the present invention that the tension rods 1 and 2, which form thelower boom of the girder, are not utilized as supports for the bay shutterings, and the lengths of the bent-over extensions 3a are so dimensioned that the shuttering or plaster-carrying batten Sisso spaced below the lower boom rods 1 and 2 that the latter are bound into the concrete along'with the prescribed amount of covering.

Referring now to Figs. and 6in detail, there'is shown another embodiment of the present invention. In said embodiment the lower boom is constituted by four rods 1, 1a, 2 and 2a. Said rods are all disposed in the. same plane andare secured together in laterally spaced disposition by transverse rods 3b which are secured across the tops thereof at spaced points longitudinally thereof.

The supporting web isformed'by a round rod 4a which is of serpentine or zig-zag conformation and which en gages below each second or altern'ate'transverse rod 3b. After the girder has been manufactured or formed, the transverse rods 31) are bent over symmetrically, from the condition thereof shown in Fig. 6, to the plane of the girder web, as shown in Fig. 5, so as to grip the sheet metal supports 14. Said sheet metal supports 14 are recessed at opposing edges thereof, as at 15. The lower boom rods 1a and 2a are disposed in said recesses 15, respectively, so as'to anchor the supports 14 in position on the lower boom. In order to prevent the tilting thereof, the supports 14 are provided at the edges thereof which are encompassed or surrounded by the transverse rods 3b, with bent-over edge portions 1411. A channelshaped stirrup strap 6:: is bent out from the lower edge of each support 14. Each stirrup strap 6a functions in the same manner as the previously described stirrup 6 as a support for a batten 8. In the present embodiment also, the height of the supports 14, or the extending distance thereof below the lower boom is so chosen or dimensioned that the stirrup strap 6a or the batten 8' supported thereby and which serves as a support for the bay shutteringor the clamping strap thereof, ensures that the lower boom rods 1a and 2a will be covered to the necessary extent by the situ-mixed concrete.

Referring now to Figs. 7 and 8 in detail, there is shown as additional embodiment of the present invention. In the present embodiment, the downwardly directed legs 3a of Fig. 3 are reflexed at their free ends to form the extensions 5 which are parallel to the tension rods 1 and 2. In order to accommodate said extensions 5, the

previously described stirrup bands 6 .of Fig. .3 are provided with eyes 7, bent out therefrom, in which the extensions 5 are received. In all other respects, the present embodiment is similar to the embodiment of Figs. l-4.

While the present invention has been in connection with girders formed of steel, it will be understood that it is not limited thereto and that other suitable girder materials may be used.

From the foregoing it will be apparent that the present invention is well adapted to fulfill the previously listed objects thereof.

While there are shown and described'the preferred embodiments of the invention, it will be understood that various changes may be made in the idea or principles thereof within the scope of the appended claim.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent, is:

A girder structure comprising a web, an elongated boom provided on said web, said boo-m being formed of at least a pair of parallel longitudinally extending tension members, a plurality of spaced apart substantially U-shaped transverse members extending across and above said tension members and supported thereby at spaced locations longitudinally of said tension members, said transverse members being secured to'said web and to said tension members and retaining said tension members in spaced relation, said transverse members including a pair of downwardly extending legs terminating in free ends, which form extensions of said legs and project normal to said legs, said leg extensions being directed parallel to said tension members, stirrup bands arranged in spaced relation to each other, and a batten mounted on said stirrup bands, said stirrup bands constituting channelshaped elements having downwardly opening channels including web portions and flanges terminating. in end portions and being provided with eyelets in said web portions and offset with respect to the remainder of said stirrup bands, said batten being received in said downwardly opening channels, said extensions being received in said eyelets to support said batten, said web portions of said stirrup bands overlying said batten, said batten being retained in said channels of said stirrup bands by said terminating end portions underlying said batten and being engaged therewith.

References Cited in the file of this patent UNITED STATES PATENTS 1,953,315 Sereff c Apr. 3, 1934 2,357,408 Kupec'et a1 'Sept. 5, 1944 2,728,595 Wong Dec. 27, 1955 FOREIGN PATENTS 464,676 Canada I Apr. 25, 1950 804,118 Germany Apr. 16, 1951 896,999 Germany .-.Nov. 1 6, 1953 1,114,671 France ......a Dec. 19, 1955 185,549 Austria May 11, 1956

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