US1971051A - Structural element - Google Patents

Description

Aug. 2l, 1934. M. REINER Er AL 1,971,051

STRUCTURAL ELEMENT Filed May 9, 1933 2 Sheets-*Sheet 1 Huh.

{17A/eras F15/NEE. *m 4 afa/ ATTOE N EYS Aug. 21, 1934. M. REINER l-.T AL 1,971,051

STRUCTURAL ELEMENT Filed May 9. 1933 2 Sheets-Sheet 2 FIG. 5-

vmvsrnores F7 8 n Evers/vc C/VG'HAM MAL/AMJ ome Mera.: Eem/Ee ATTORNEYS Patented Aug. 21, 1934 istinti STRUCTURAL ELEMENT Markus Reiner, Jerusalem, Palestine, and Eugene C. Bingham and William S. Lohr, Easton, Pa.

Application May 9, 1933, Serial No. 670,060

Claims.

The invention provides an improvement whereby greater strength and economy is obtained in structural elements such as columns, pillars, arches and the like which are of greater "i length in one direction than in the other two These objects are secured by encasing the con-V crete orrthe like in a shell which is specially adapted to carry tensile stresses; such as steel or metal, wood, paper, textile materials and other compositions, depending upon the uses to which the element is to be put, and the strains and other conditions to which it is to be subjected. The parts are so arranged thatthe shell is subjected wholly or mainly to pressure acting in directions normal to its internal surface so as to produce stresses in tension only or mainly, The longitudinal compressive stresses on the core '30 are not transmitted directly to the shell but are resolved into components in the direction stated.

The accompanying drawings illustrate embodiments of the invention, being, however, only a few of the various forms in which the principle may be applied.

A Fig, 1Y is a longitudinal section of a complete column;

Fig. 2 is a cross-section of the same; Fig. 3 is a cross-section of a similar column which is rectangular instead of circular;

Fig. 4 is a longitudinal section of a modification;

Fig. 5 is a longitudinal section of an arch; Fig. 6 is a longitudinal section of a modied form of arch;

Fig. 7 is a cross-section of the arch of Fig. 5 near one end;

Fig. 8 is a longitudinal section of the lower portion of another modication. 50 Referring to Fig. 1, the column has a base member with a vertical flange 1 and a horizontal plate 2 which rests on the support 3. At the upper end there is a similar member forming a downward ilange 4 and horizontal cap plate 5 for transmitting the load 9. The core 6 is of (Cl. 'i2-75) concrete. This may be the usual concrete made of cement, sand and broken stone. It is encased in a steel shell 7.

The arch of Fig. 5 is on the same principle as the column of Fig. 1 with steel end pieces 1, 2 60 and 4, 5 at opposite ends for taking the thrust on the abutments 3.

The flanges 1 and 4 enter the shell 'l and conne the concrete in the short distance which is left between the ends of the shell 7 and the plates 65v 2 and 5 respectively.

In the case of a circular section, the shell 'l is continuous as shown in Fig. 2. Where a rectangular section is used, as in Figs. 3 and 7, a correspondingly shaped shell is provided with angles 8 at the corners which stiien the shell and may be used to join plates constituting the several sides. Q

In the case of Figs. 4 and 6, the construction is similar to that of Figs. 1 and 5, but omitting-the 75 end plates.V There is a clearance between eachI of the ends of the casing 7 and the adjacent abutment. But this is so slight that it dees not seriously impair the strength of the element.

It has been found that when concrete, 'either' plain or with the ordinary reinforcement, is sub? jected to sustained compressive stresses, it shows a certain plasticity and permits considerabledeiormation, much in excess of the elastic deformation. This brings with it an over-stressing of the usual reinforcing steel rods, which may ulti-j mately bring failure to the structure.

The usual method of reinforcing such concrete elements in compression has been based on con-` siderations of purely elastic deformation and, therefore, cannot lead to stable and safe struc? tures. Longitudinal steel reinforcing rods do not serve any substantial useful purpose in structural elements which are in pure compression. Plastic deformation can be prevented only by hindering the structural element from the lateral expansion which accompanies longitudinal shortening.

This is accomplished in the present invention by the encasing of the core in a steel shell. No other reinforcement is necessary. Hollow steel columns have heretofore been lled with concrete. But in that case the steel column carried the major part or a Very `considerable part of the longitudinal stresses and, therefore, was in danger of buckling. By providing for a slight play between the ends of the shell and the adjacent abutments, we eliminate longitudinal compressive stresses in the shell or reduce them to negligible quantities.

Whileit is possible to use a shell with small soV strain tending to buckle it. This may be accom? plished by a sort of piston arrangement telescoping with the shell and transmitting pressure directly to the core as in Fig. 1, or by merely leaving a gap or slight play between the ends of the shell and the abutments so that the latter bear only on the core as in Fig. 2.

The shell can be used as a form for the core, thus obviating the necessity of using ordinary concrete-pouring forms.` Y

In order to protect the steel or other material of the shell from corrosion, or from the effects Y of re, any of the usual protective schemes may be used such, for example, as painting and rustproo'ng', or covering with gypsum, terra cotta or other fireproong material.

In order that the stresses imposedby the concrete on the shell shall be solely in the radial directions, normal to the'inner face of theY shell at the point of application, it would be necessary to prevent adhesion between` the core and the shell. Generally adhesion of the concrete to the steel will not besuch as to materially affect the working-out of the principles of the invention, and the concrete can be cast directly into the shell. However, the inside surface of the shell may be first covered with a coating '7a (Fig. 8) of grease,

` oil, asphalt, paint or some other material Which lessens the adhesion to a determined limit, or may be covered with a layer fof paper -or the like for the same purpose.

The quality of the materials of which the core is made is of secondary importance as long Aas the pore spaces are completely filled. This means great economy in the amount and quality of the cement used. The cementing medium, in fact, instead of being hydraulic cement may be a composi- Vtion which is more commonly recognized as viscous, such for example as asphalt and other bituminous compositions. Furthermore, the concrete may be made to carry a considerably higher Working unit stress than heretofore, which means a decrease in the cross-section and an economy in materials and iloor space. The steel or other shell at the same time is used with its greatest economy because it is subjected mainly or wholly to tension and is not in danger of buckling.

Although no reinforcement of the concrete within the shell is necessary, such supplementary reinforcement may be used. Also the shell, instead of being of plain sheet metal, may be reinforced by making it of special shapes, or by the j application of supplementary reinforcements of any usual or suitable type.

Various modifications other than those described may be made by those skilled in the art Without departing from the invention as Adefined in the following claims.

What we claim is:--

1. A structural element for carrying longitudinal compression, comprising a core of material adapted to withstand compression and having a certain plasticity under sustained pressure and a shell enclosing said core so as to prevent expansion of any substantial part thereof radially beyond the shell and formed of a material adapted to carry tensile stresses, the ends of the core in use being exposed to the external longitudinal pressures and the shell in use being exposed only to the radial pressures of the core within it.

2. The structural element of claim 1,.in combination with plates at the ends ofthe core with inward flanges through which plates the longitudinal forces are transmitted to the core.

3. The structural element of claim 1, in combination With a coating of material between the core and the shell which is adapted to prevent or restrict the adhesionbetween the core and the shell.

4. A structural element for carrying longitudinal compression, comprising a core of concrete to the ends of which the external longitudinal forces are applied and an enclosing metallic shell, the core projecting at the ends beyondthe shell so as to avoid transmission of longitudinal forces to the shell.

5. The structural element of claim 4, .in combination with metallic plates at the ends of the core provided with inward flanges telescoping with the shell. Y

6. The structural element of claim 1, the core being molded Within the shell.

7. A structural element for carrying longitudina'l compression, comprising a core of concrete to the ends of which the external longitudinal forces are applied and an enclosing metallic shell, the core projecting at the endsbeyond the shell so as to avoid transmission of longitudinal forces to the shell, the concrete of the core being made up of aggregate and a viscous material.

8. The structural element of claim '7 in `combination with Vmetallic plates at the ends of the core provided With inward iianges telescoping with the shell. v

9. A structural element for carrying'longitw dinal compression, comprising a core of concrete to the ends of which the external longitudinal forcesare applied and anenclosing .metallic shell, thecore projecting at the ends beyond the shell so asV to avoid transmission of longitudinal forces tothe shell, and a coating of material between the concrete and the shell Which is adapted to prevent or restrict the adhesion between the ycore and the shell. V

10. The structural element of claim 9, combination with metallic plates at the ends of the core provided with inward flanges telescoping with the shell.

11. The structural element of claim 1, the core being molded Within the shell, in combination with plates Aat the ends of the core with inward anges through which plates the longitudinal forces are transmitted to the core.

12. The structural element of claim 4, the core being molded within the shell and consisting of aggregate and a viscous material.

13. The structural element of claim '4, the core being'molded within the shell and consisting of aggregate and a viscous material in combination with metallic plates at Vthe ends of the core provided with inward anges telescoping with the shell.

14. The structural element of claim 1 in com-v bination with an abutment, the end of the shell being separated by a certain play from the abutment and the end of the core having `a direct engagement with the and formed of a material adapted to carry tensile stresses, the core alone being subjected to the longitudinal pressures from the adjacent parts of the structure, and the shell being subjected only to the radial pressures of the core within it.

MARKUS REINER. EUGENE C. BINGHAM. WILLIAM S. LOHR.

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