US2697930A

US2697930A - Slab supporting frame for reinforced concrete building construction

Info

Publication number: US2697930A
Application number: US150928A
Authority: US
Inventors: David B Cheskin
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-03-21
Filing date: 1950-03-21
Publication date: 1954-12-28
Anticipated expiration: 1971-12-28

Description

1954 D. B. CHESKIN SLAB SUPPORTING FRAME FOR REINFORCED CONCRETE BUILDING CONSTRUCTION Filed March 21, 1950 FIE E FIE- 1 A q 12,0 7T 2/ f 9 m km I P iv m wi "1 7 i l I T n I l I l I I 4 F1 ||/L ,IZ m m 9 Z Z 0/ m L PIE. 5

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United States Patent SLAB SUPPORTING FRAME FOR REINFORCED CONCRETE BUILDING CONSTRUCTION David B. Cheskin, Chicago, Ill.

Application March 21, 1950, Serial No. 150,928 9 Claims. (Cl. 72-15) 1 This invention relates to an improved type of slab supporting frame in a reinforced concrete flat slab and column construction. More specifically, the invention provides a structural steel frame which transmits shear and compression from a flat slab to its supporting column in a manner permitting the elimination of haunches, drop panels, or column caps and the like, in a reinforced concrete building construction.

In general, the flat slab and column construction is of advantage over the slab, beam and girder construction, in that it eliminates expensive form work and labor, as well as, provides a method of construction which results in greater clear space between floor slabs. The slab and column construction also permits the placing of reinforcing in a quicker and easier manner. However, it is sometimes difficult to design the slab and column type of construction for heavily loaded floors, without the use of large haunches or small slabs, or alternatively, having the columns spaced relatively close to one another in order to properly transfer the slab loadings to the columns. Slab supporting frames or shear-compression heads, such as provided by this invention, are used to advantage in the slab and column concrete construction to eliminate large haunches or drop panels and to satisfactorily transfer the floor loadings to the columns. The supporting frames, in addition to transferring the shear and compression stresses to the columns, serve to stiffen the slab at the columns and thereby permit the use of relatively thin floor slabs, being the equivalent of the column haunches or drop panels.

Various types of heads or slab supporting frames have been incorporated in reinforced building construction, but, in general they have not been of a type readily fabricated or readily positioned and incorporated with a concrete column and floor slab. The present supporting frame is designed in a manner which does not interfere with the pouring of the concrete columns and in addition is fabricated of structural steel members in a manner to properly provide bond with the floor slab and the vertical columns. They are also easily set into the form work and normal operations for setting the slab and column reinforcing, as well as the pouring of the concrete,

In other words, the reinforced concrete design for the entire building may be as desired, and the placing of the slab reinforcing steel and the design of the vertical reinforced columns is in no way limited by this improved slab supporting frame.

It is a principal object of this invention to provide and employ a shear-compress1on head, or slab supporting frame, which provides outwardly projecting members of standard structural steel members in a manner to develop a maximum amount of bond with the concrete floor sla'b and column.

It is a further object of the invention to provide a frame having channel-shaped steel upright members positioned vertically between outwardly projecting bent and flanged members in a manner to advantageously space the latter, as well as provide means for attaching the frame to the supporting column.

It is a still further object of the invention to provide a slab supporting frame which not only develops a high degree of bond with the concrete, but which in addition is effective to transfer bending and shear stresses longitudinally through the frame to develop a high degree of beam action.

Briefly, the improved slab supporting frame of this in- Patented Dec. 28, 1954 vention, which provides a particularly satisfactory means of transferring floor loadings to the columns in a reinforced concrete slab and column building construction, comprises, a plurality of spaced bent structural steel mem' bers having their end portions project outwardly from an inside bent section thereof, and suitable for encase= ment in the con-crete floor slab, a flanged structural mem-' ber positioned vertically between each of the bent mem= bers at a point adjacent the bent sections thereof, with the vertical or upright structural members having their flanged portions connecting to the outwardly projecting end portions of the bent members and thereby elfecting the spacing of the latter at the supporting column as well as the attachment of the resulting slab supporting frame to the supporting column.

The bent structural members may have one or more bends which are in the zone of the reinforced concrete column, while the intermediately positioned upright members are attached to the bent structural members adjacent their bends to provide an open portion at the center of the frame, in a manner which permits the concrete to be readily poured during the building construction. The bends of the outwardly projecting members and the positioning of the upright members are, however, made to conform with the column design, in order to permit the placing of vertical reinforcing bars and ties for the concrete columns. In a preferable embodiment, the upright members are structural steel channels which provide the open center portion and also are adapted for attachment to I-beam or H-sections in a composite column construction. The bent structural members maybe standard rolled beam shapes, or likewise channel shapes, such that the flanges of the vertical channels may be attached directly to the back of the bent channel members. In the fabrication of the horizontally placed and outwardly projecting members, the bends are formed by notching the flanges and subsequently welding them to provide any bend that may be desired. Flanged I-beam sections may be stripped at the upright members for attachment thereto and notched to form desired bends.

A preferred construction of the slab supporting frame has similar bends for each of the adjacent outwardly projecting members, such that the end portions thereof extend in a symmetrical pattern or extend parallel with end portions of the next adjacent bent members. The end portions of adjacent members may extend parallel to one another at a spacing equivalent to that of the distance between flanges of the upright channel members, or alternatively, the adjacent end portions may be spaced only at the zone of the supporting column and either converge or diverge as they extend outwardly from their bent sectrons.

It is a particular advantage of the present improved supporting frame to maintain the open center portion and the adjacent outwardly extending end portions separated from one another in order to develop a maximum degree of bond with concrete floor slabs. The vertical members extend above and below the outwardly projecting bent members at a distance sufiicient to satisfactorily attach or incorporate the supporting frame with the vertical columns. The upright channel sections also preferably utilize web and flange stifieners between their flanges at the zone of connection with the bent members in order to provide continuity between adjacent bent members and more efliciently accommodate shear and compression stresses, as well as bending stresses which are developed by the slab loadings.

Still another embodiment of the improved shear-compression head, or slab supporting frame, incorporates a plurality of structural steel members laterally between the outwardly projecting end portions of the bent members, providing means to obtain additional bond with the con crete. These additional lateral members are standard rolled sections, or built-up sections, and are preferably framed between the bent members in a continuous ringlike manner. One or more rings of the lateral framing members may be utilized, depending upon the amount of bond desired. It may, however, be noted that the lateral members which are framed between and connect to the outwardly projecting end portions of the bent members serve to stiffen the latter, as well as provide additional bond and thus permit smaller sections for the outwardly projecting bent members.

Reference to the accompanying drawing and the following description thereof-will serve to more clearly illustrate the construction and arrangement of the improved slab supporting frame, as well as point out additional advantages in its incorporation with reinforced concrete slabs and columns.

Figure 1 in the drawing is a diagrammatic plan view of one embodiment of the improved shear-compression head.

Figure 2 of the drawing is a diagrammatic plan view of a diiferent embodiment of the improved frame, utilizing right angle bends in the horizontal members.

Figure 3 of the drawing is a sectional elevation view of the shear-compression head or supporting frame, as indicated by the line 3-3 in Figure 2 of the drawing.

Figure 4- of the drawing is a modified embodiment illustrating the use of lateral stiifeners or framing members,

in order to provide additional bond and a highly rigid slab supporting frame.

Figure 5 of the drawing is a sectional view through the intermediate channel-shaped framing members, such as indicated by the line 5-5 of Figure 4 of the drawing.

Figure 6 is another modification of the frame, with but two upright channel members.

Referring now to Figure l of the drawing, there is shown by the broken line a circular reinforced column 1, with suitable reinforcing bars 2, which may utilize to advantage a slab supporting frame of the present invention. The supporting frame comprises a plurality of channel shaped members 3, each of which have two bends 4 each side of a relatively short straight section 5', and two long end portions which extend laterally outwardly away from the bends 4 and the supporting column 1 in a manner to be encased within the reinforced concrete floor slab. Between each of the bent channel members 3:, and adjacent the bends 4, is a vertically positioned channel member 6. Each of the channels 6 extend above and below the bent mem bers 3 a suflicient distance to adequately attach or connect these slab supporting frames with the reinforced concrete column. The channels 6 may have their flanges turned either inwardly or outwardly, however, the vertical members preferably attach to the bent members closely adjacent the bends 4 in order that they be well encased within the concrete column. The flanges of the upright channels 6 may be riveted, welded or otherwise attached to the backs of the bent members. Web stitfeners 7 are also utilized in a preferable embodiment between the flanges of the vertical channels 6 at a level corresponding closely to the positions of the flanges of the horizontal bent members 3. Thus, the bending and shear-compression stresses are more readily transferred through the frame to provide continuity and a beam action.

The embodiment of Fi ure 1 shows four bent members 3 and four vertical members 6 spaced between each of the bent members such that an octagon-shaped opening is formed at the center of the supporting frame and the concrete column. The octagon-shaped opening provides a relatively large clear area which permits easy pouring of concrete at the column and slab juncture. The octagonshaped opening of this frame is also particularly adaptable to circular reinforced concrete columns, although it need not be limited to circular columns, for square or other polygonally shaped columns may be used advantageously therewith. The present embodiment indicates the outwardly projecting end portions or legs of the bent members 3', as forming four sets of parallel end portions. In other words, each of the bent members have equal inside angles formed at 135, and the vertical channel members 6 have flanges which are at right angles to their backs, so that adjacent end portions extend parallel to one another a spaced distance apart equivalent to the distance between flanges of the vertical members 6.

Although not shown in Figure 1, horizontal members may be framed between the outwardly projecting portions of the bent members to provide leg stiffening and to effect additional bond with the floor slabs. Preferably, these members, which are framed laterally between end portions or legs, extend in ring-like manner continuously around the entire slab supporting frame. One or more rings of the lateral members may be used intermediately, or at the outside periphery of the supporting frame.

Referring now to Figures 2 and 3 of the drawing, there is indicated a slightly different embodiment of the im- "sets of outwardly projecting end portions.

proved slab supporting frame with bent structural channel members 8 and vertical channel members 9. Each of the horizontal and outwardly projecting members 3 have a single right angle bend 10 such that a total of four bent members 8 are utilized in the frame and there are four As described in connection with Figure l of the drawing, the vertical or upright channel members 9 have their flanges connected to adjacent bent members 8 at a point near each of the bent sections. Thus, the bent members 8 are spaced apart at the vertical reinforced concrete column a distance equal to the depth or distanceback to back of flanges of the members 9. In the case of right angle bends 10 and flanges on the vertical channels 9 at right angles to their backs, the outwardly projecting legs or end portions of members 8 extend in four sets of parallel leg members, with a resulting formation of a cross shape frame. The vertical channel members may be connected to the horizontal bent members by welding, riveting, or other conventional means, as herein before noted. The upright vertical channels 9 have web stifieners 11 between the flanges thereof, which as shown in Figure 3, are preferably in substantial horizontal alignment with the upper and lower flanges of the channel members 8. Also, previously noted, this insures rigidity and continuity through the supporting frame and better accommodates the shear and compression forces which are exerted on the frame.

The cross-shaped frame of Figures 2 and 3 is indicated as being incorporated in a square reinforced concrete column 12, however, it may well be used with circular or other conventionally shaped columns, or with a composite steel and concrete column. The backs of the vertically positioned channels are particularly adapted for attachment to a vertical column member, such as column 22, in a composite type of building construction.

Figure 4 of the drawing is a modified cross-shaped slab supporting frame, similar to that of Figure 2, having four bent members l3 and four spacing and vertically positioned channel members 14. Each of the bent members 13 have right angle bends l5'so that their outwardly projecting leg or end portions result in parallel spaced members forming the four outwardly projecting sets. This embodiment also shows an inner ring formed of lateral framing intermediate members 16 and 17. The members 16 connect to and frame between the outwardly projecting legs of bent members 13, while lateral stiffening and framing members 17 connect to and frame between the more closely spaced legs of adjacent bent members 13. A second continuous ring is formed outside of, or beyond the inner ring, by

members

18 and 19. The members 18 connect to and frame between the two outwardly projecting legs of bent members 13, while like the members 17, the outer members 19 connect to and frame between the more closely spaced legs or end portions of adjacent bent members 13.

These lateral framing members which provide both the inner and outer rings shown in Figure 4, may be channel members, however, they may be other rolled sections or built-up sections. As shown in Figure 5 of the drawing, the lateral members l6, 17, It? and .19 may be formed of structural angles tied with suitable bars of plate members 20. The use of angles or ties with tie plates and bars provide a construction which effects an increased bond with the concrete floor slabs. Further, these lateral members may be tipped or posi- Lioned at an angle when framed betw en the bentmemers.

It may also be noted in Figure 4 of the drawing, that the vertical channels 1 have their flanges turned inwardly toward the center of the concrete supporting column. However, they are preferably welded or suitably attached to bent members 13 at a point close to or adjacent the bends l5 and have web stiffeners 21, so th t the resulting frame has a-high degree of rigidity as described.

Referring now to Figure 6 of the drawing, there is shown a still further embodiment of the supporting frame, when only two upright channel members 23 and two bent members 24 are utilized. The latter members 24 are I-beam or H-beam sections and are notched and bent to provide means for connection to the vertical channels 23, as well as permit a single flanged section to form two outwardly projecting legs of the frame, with two notches and bends 25 in each. The flanges of the horizontal members 24 are welded to the flanges of'uprights 23 and the web 24' is also-welded or otherwise connected to the corners of the channels on the inside portionof the frame. Web stiffeners 26, as in the other embodiments, are desirable to reinforcethe-upright members at the zone of attachment to the horizontal outwardly projecting members and provide Continuity and rigidity to the frame. This frame is of very simplified construction, providing a minimum of upright members, but a strong construction which maybe attached to any type of reinforced or composite type of concrete column. Lateral framing members may also be used between the legs or ends of the bent flanged members.

By way of summary it may be noted that the shearcompression head, or the slab supporting frame, of this invention utilizes standard flanged sections for the continuous bent members, and channel-shaped vertical supporting members. Flanged members may be notched and readily bent, in an easy fabrication operation, to form continuous bent members. The vertical channels have flanges which are readily attached to the bent members and effect a spacing of the latter, while in the case of the spaced channel sections, the spaced projecting end portions, or legs, develop greater bond than is possible with designs which utilize a single outwardly projecting leg, or channels which are in a back to back position. The vertical channel members are also effective in developing a good bond with reinforced concrete columns, or for effecting attachment with steel columns in a composite type of concrete building construction. It is also a feature of the improved construction to place the vertical members away from the center of the concrete column, so that as previously noted a clear area is maintained for pouring concrete. Further, the vertical members are placed close to the bent sections of the horizontal members so that web stilfeners placed in the vertical members are effective to transfer stresses across the frame. While lateral framing members, forming the substantial continuous rings around the frame, are shown only in Figure 4 of the drawing, it is to be understood that one or more rings of the framing members may be incorporated with the supporting frames of Figures 1, 2 and 6, or such other embodiments as may be formed between the bent horizontal members spaced apart by the upright channel members, in accordance with the improved design and construction.

I claim as my invention:

1. A slab supporting frame for use with a reinforced concrete supporting column, which comprises, a plurality of bent structural steel channel members having their end portions projecting outwardly from an inside bent section thereof, separate straight structural steel channel members positioned with the flanges thereof extending vertically between each of said outwardly projecting end portions of next adjacent bent channel members at a point adjacent the bent sections thereof, with said straight vertically extending channel members having their flanged portions rigidly attached to said bent channel members and extending above and below the latter, and said straight vertically extending channel members spacing said bent members, and each of said bent structural steel channel members have an end portion thereof extending parallel to an adjacent end portion of the next adjacent bent channel member to provide thereby a plurality of outwardly projecting sets of end portions, with the latter being spaced in each set the distance between flanges of said vertical channel members.

2. The slab supporting frame of claim 1 further characterized in that a plurality of structural members connect to and frame horizontally between the outwardly projecting end portions of said bent channel members, said interconnecting members forming continuous ringlike framing around said slab supporting frame.

3. A floor slab supporting frame for use with a concrete supporting column, which comprises, a plurality of bent one piece structural steel members, each of the latter having a right angle bend and end portions thereof projecting outwardly from the heel of said right angle bend, vertical channel-shaped structural members positioned between each of said plurality of bent structural members at a point adjacent the heel of said bent section, said vertical channel members having their flanged portions extending vertically and attached to the outwardly projecting end portion of adjacent bent members whereby to elfect the spacing of the latter at said supporting column a distance equal to the back to back of flanges of said channel-shaped members, and said vertical members extend above and below said bent members, and each of said bent structural steel channel members have an end portion thereof extending parallel to an adjacent end portion of the next adjacent bent channel member to provide thereby a plurality of outwardly projecting sets of end portions, with the latter being spaced in each set the distance between flanges of said vertical channel members.

4. A slab supporting frame for use with a reinforced concrete supporting column, which comprises,four'bent structural channel members, each of the latter having a right angle bend at the center portion thereof and end portions projecting outwardly from the right angle bend, straight vertical structural steel channel members positioned between each of said plurality of bent channel members at a point close to said right angle bends of said bent channel members, said straight vertical channel members having their flanged portions extending vertically and attached rigidly to the backs of the outwardly projecting end portions of each adjacent bent channel member whereby to effect the spacing of the latter, with said vertical channel members extending above and below said bent members for efiecting the attachment of said slab supporting frame with said supporting column, said right angle bends in said bent channel members forming with adjacent end portions of bent channel members four sets of outwardly projecting parallel end portions, with each of the latter spaced apart the distance between flanges of said vertical channel members, and interconnecting structural members framed horizontally between said outwardly projecting end members in a gontinuous ring-like manner around the periphery of said rame.

5. A slab supporting frame for use with a concrete supporting column, which comprises, a plurality of bent structural steel channel members, with each of the latter having two closely spaced bends therein and outwardly projecting end portions extending respectively from each of the two bends, upright channel-shaped structural members positioned between each of said plurality of bent channel members at points adjacent said bends, each of said upright channel-shaped members having their flanges extending vertically and attached to the outwardly projecting end portions of said bent members elfecting the spacing of the latter a distance equal to the width between flanges of said upright channel members, and each of said upright channel-shaped members extending above and below said bent structural members suitable for attaching said frame with said supporting column, and each of said bent structural steel channel members have an end portion thereof extending parallel to an adjacent end portion of the next adjacent bent channel member to provide thereby a plurality of outwardly projecting sets of end portions, with the latter being spaced in each set the distance between flanges of said vertical channel members.

6. The supporting frame of claim 5 further characterized in that there are four bent structural members with each bend forming an inside angle of and four upright channel-shaped members are placed between the outwardly projecting end portions of the adjacent bent structural members providing four sets of outwardly projecting portions, with each of the end portions of each set being spaced apart equal to the distance between flanges of said upright channel-shaped members.

7. The slab supporting frame of claim 6 still further characterized in that the backs of the channel-shaped upright members oppose one another at said supporting column and are adjacent the bends of each of the bent structural steel members to form thereby an octagon- ;haped central opening through said slab supporting rame.

8. The slab supporting frame of claim 5 further characterized in that the bent structural steel members. are steel channels, the vertical members are structural steel channels, and additional structural members are connected to and framed between said outwardly projecting end portions of said bent members providing continuous stiflening and ring-like framing members around said slab supporting frame.

1 9. A slab-supporting frame for use with a reinforced concrete supporting column, which comprises, a plurality of bent structural steel members having their end portions projecting outwardly from an inside bent section ythereof for encasementain;a slab isection, 'iflanged :channel members-positioned. .vertically: between each oft said outwardly projectingend portions: of: said bent members at a point adjacent the :bent sections thereof, said vertical channel members having th'eir ,flangedportions extending vertically and attached -to said-outwardly 'pro- -jecting end-portions of said bentinembers and thereby spacing the latter at said supporting column the :distance between flanges of said vertical channel-members, andefiectingthe attachment of said frame toisaid supporting column, andeach of said bentstructural steel members having an end portion thereof extending parallel to an adjacent end portion of the next adjacent structural member to provide. thereby a plurality. of outwardly .projecting sets :of end portions, with therlatterheing s spacedin each set the di'stance*betweenflanges of said vertical channel members.

- References Cited in the file of this patent UNITED STATES PATENTS Number Name Date I 681,304 -Fe1t Aug. 27, 1901 1,009,712 Anderson 'Nov. 28, 1911 1,088,956 Anderson Mar. 3, 1914 1,128,912 Snyder Feb. 16, 1915 1,973,741 Bauer Sept. 18, 1934 2,033,595 Strehan Mar. 10, 1936 2,469,455 D'onahueet a1. May 10, 1949