US1977371A - Plate girder - Google Patents

Description

F. BAUER PLATE GIRDER Oct. 16, 1934.

Filed March 5, 1951 Zwenior fF/[z Bauer All Patented Oct. 16, 1934 UN 1 f 1 PLATE Gianna Fritz Bauer, Stuttgart, Germany Application March 5, 1931, Serial No. 520,389 In Germany March 3, 1930 5 Claims; (01; 72 -s1) My invention relates to concrete-steel hollow plate girders. It is, an object of my invention to provide a hollow plate girder of comparatively low weight and low initial cost. Y

To this end I build up mynovel girder from a hollow metal member of channel section in combination witha concrete body at the open side of the member. Only the flanges of the -channel-section member are embedded in the concrete body with their outer margins only, so that the concrete does not embed the whole channel member.

It has already been suggested in girders having a hollow steel member and a body of concrete to provide the hollow member at the neutral zone or at points which are not particularly important for the moment of resistance, with the object of reducing the weight or providing facilities for connecting other parts to the girder. Such hollow members, however, play a secondary part in the load capacity of the girder. The sole weight of the girder is normally much. higher than the weight of a wooden beam of equal size While the initial cost is very high onaccount of the considerable amount of material required.

According to my invention I provide a concrete steel girder in which the hollow member takes its share of the stresses. Such a girder has about the same weight as a wooden girder of equal size, but its initial cost is so low on account of the limited quantity of material required that structures including my novel girders, for in stance ceilings, are much cheaper than other systems.

In building up a girder in accordance with my invention I provide'a hollow steel member the section of which is so determined that its sole weight and the superload on the girder are supported by the steel member while the concrete body is made of such section as to prevent buckling of the steel member.

As compared with concrete-steel girders as designed heretofore the body of concrete is comparatively thin, as only a small section of concrete is required for preventing deformation of the girder by the fast-sticking concrete.

My novel girder is adapted to be fabricated at the works and to be shipped to the field like any other girder or wooden beam. 7

In the drawing afiixed to this specification and forming part thereof several types of girders embodying my invention are illustrated diagrammatically by way of example.

In the drawing V Fig. 1 isa section of a'girder having a tu bular metalmember of channel section, with a concrete body at its tension side,

Fig. 2 is a section of a girder having an inverted metal member of channel section, and plain metal bars in the concrete body,

Fig. 3 is a perspective illustration, partly in section, of a ceiling with the element shown in Figs. 1 and 2 built in as girders.

Referring now to the drawing, and first to Fig. l, a. is a member of steel or other suitable material which is here shown as an inverted channel section, with its open side facing the tension side of the girder, and v is a body or block of concrete at the tension side. The outer margins of the flanges of the channel-section member a are turned up horizontally at as and a bottom plate 71. having upturned edges 2' is secured to the turned-up portions of the margins. m are hooks which are placed on the turned-up portions a: for effecting a connection as will be described with reference to Fig. 3.

Referring now to Fig. 2, the section of this element is substantially similar to that illustrated in Fig. 1 but without the bottom plate It so that it is a mere trough or channel and not a tube as in Fig. 1. The flanges at the open side or bottom of the section a are provided with turned -up portions :0 as shown in Fig. 1, g are horizontal stirrups having hooks at both ends for engaging the turned-up portions and vertical stirrups n are inserted between the ties f and the turned-up portions :2: with their lower ends. The stirrups it serve the same purpose as the hooks m as will be described with reference to Fig. 3.

My novel elements may form part of any structure and by way of example a ceiling is illustrated in Fig. 3, in which p are hollow members of any suitable section forming part of the ceiling. Girders according to my invention are combined with the hollow members and in the present instance. the girder illustrated'in Fig. 2 has been shown at three points, slightly modified. The first girder from the left has horiwith concrete q. Obviously, the tubular member shown in Fig. 1 might also be inserted as part of the structure shown in Fig. 3.

The edges of the steel member a and the members at its bottom, to wit, the stirrups g, the plate h (of expanded metal if desired) and the wire netting k: are firmly anchored in the block 1) and buckling is prevented. The hooks m or the stirrups n serve as connecting links between the steel member a and the concrete fillers q, Fig. 3.

If desired, the ceiling might be built up from girders placed side by side instead of pitching the girders apart and inserting the hollow members p between them, as shown.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.

In the claims affixed to this specification no selection of any particular modification of the invention is intended to the exclusion of other modifications thereof and the right to subsequently make claim to any modification not covered by these claims is expressly reserved.

I claim:

1. A plate girder comprising a hollow metal "member of channel section, and a concrete body at the open side of said member in which body the flanges of said member are embedded at their margins.

2. A plate girder comprising a hollow metal member of channel section whose Web is arched and whose flanges diverge toward the opening of said member from its arched web, and a concrete body at the open side of said member in which body the flanges of said. memberare embedded at their margins. I

3. A plate girder comprising a hollow metal member of channel section, a concrete body at the tension side of said member in which body the flanges of said member are embedded at their margins, and reinforcing members in said body.

4. A plate girder comprising a hollow metal member of channel section, a concrete body at the tension side of said member in which body the flanges of said member are embedded at their margins, and reinforcing members in said body whose ends are connected to the flanges of said member.

5. A plate girder comprising a hollow metal member of channel section, a plate secured. to.

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