US1057531A - Reinforcement for concrete flat slabs. - Google Patents

Description

W. C. EDWARDS, JR.

REINFORCEMENT FOR CONCRETE FLAT SLABS. APPLICATION riLnn JULY 31. m2

1,057,531 Patented Apr. 1, 1918.

15 SHEETS SHEET l W. 0. EDWARDS, JR. REINFORCEMENT FOR CONCRETE FLAT SLABS.

- Patented Apr. 1, 1913.

3 SHEBTSSHEET 3.

APPLICATION FILED JULY 31. 1912.

Q 04/ uuuuuuuuuoo rinrrnn earns rarnnr onnroir.

WILLIAM C. EDWARDS, JR., OF KANSAS CITY, MISSOURI.

REINFORCEMENT FOR CONCRETE FLAT SLABS.

Application filed July 31,

To all LU/MINI, it may concern:

Be it known that I, uau/nu C. Eownnns, Jr., a citizen of the United States of America, residing at Kansas City in the county of Jackson. and State of Missouri. have invented certain new and useful Improve-- ments in Reinforcements for Concrete Flat Slabs; and I do hereby declare that the following is a full, clear, and exact descrip-.

tion of the invention, such as will enable others to make and use the same, reference being had to'the accompanying drawings, forming a part of this specification.

The principal objects of the invention are, to provide an arrangement of steel reinforcement in flat slab concrete construction so that all stresses will be provided for,

and a true monolithic structure obtained; 'to carry the tension steel over the columns in a single layer or plate thereby increasing the effective dept-h at this criticalpoint;

to care-for all tension stresses in flat slab construction by means of reinforcing members integral with and radiating from a metallic hub pr disk situated in said slab concentric with the axis of a supporting column. 4

The flat slab concrete floor by its elimination, of beams and girders affords many adlarging the column heads, increased resistance in shear and bending is obtained. 7

In the'drawings, Figure 1.. is a plan or top view of a partially completed reinforcement for concrete fiat slab construction. Fig. 2. shows a vertical section of a completed concrete flat slab taken on a liliethrough the centers of two rectangularly positioned columns in Fig. 1. such asA and B. Fig. 3. shows a side view of the reinforcing rods seen in Fig. 2. linked to the rim of the unit, cantaliver reinforcing de:

vice at a column and radiating outward, to-

ward and under the eantaliver reinforce- Specification of Letters Patent.

llatcntcd Apr. 1. M113.

1912. Serial No. 712,436.

vertical section of a completed concrete fiat- Slab taken through the axis of a column in Fig. 1. and on a. line radiating therefrom and crossing the slab portion between columns as seen in F ig. 2. Fig. 5. shows a side view of the reinforcing rods seen in Fig. 4. linked to the unit cantaliver reinforcement at the columns and radiating outward therefrom and crossing the upper part of the slab between outer columns as seenin Fig. 1 and Fig. 2. Fig. 6. represents a vertical cross-section taken through the rim portion of the unit device of the slab reinforcement as seen at in Fig. 1. Fig. 7.

represents a section taken along the line. wm in Fig. 6. Fig. 8. is a view'showing' the approximate location of the line of inflection for imaginary beams radiating from the axis of a supporting column. Fig. 9. shows a perspective viewof a fabricated steel structural unit cantaliver reinforcing device of wheel-like construction for the fiat slab as seen in Fig. 1.-placed concentric with the columns. F ig. 10. shows a blank slitted metal plate from which is fabricated a modified form of reinforcement to that seen in. Fig. 9. Fig. 11. represents a plan view of that portion of the metal plate included within the dotted lines in Fig. 10, shown in its finished fabricated cOndit-iDn. Fig. 12. represents a side view of the sec-- tional reinforcing device seen in Fig. 11. Fig. 13. shows a section through the center of a reinforcing device formed from, the slitted plate seen in Fig. 10 and shown in its -finished condition by views indicated in Figs. 11 and 1.2, together'with portions of the slab rod reinforcement engaged there- With' and means for preventing disengagement of the said rod members.

ment over an adjacent column. Fig. 4-. shows a Similar numerals of reference indicate corresponding parts in all figures of the drawings. I

Referringto the drawings: In Fig. 1. is

seen a plan view of a partially completed reinforcement. for monolithic concrete lat slab construction,"consisting of a number of fabricated wheel-like"stee'i- .unit- 'cantaliver reinforcing d'evices'flt), Fig.9.) each placed horizontally with theiri hub portions 21 concentric with the. vertical aids of a supporting column. A plurality of spoke members 22 mains-from the hub mem ber 21, said spoke inembers terminate; at their ,outer ends" in the rim or band 23,-leaving the openings 24 in the unit device. Each device of such .cantahvcr reinforcement is forged, cast or other- Wise formed as a solid steel 'unit, the hub portion 21,. being the central portion of each pair of opposite spoke members 22 and 22, is thus formed as a disk of-s'uch size that a sufliciently large amount of steel can be concentrated in a single layer nearthe upper part of the slab-directly over the ecnterofthe supporting column for the purpose further set forth. The spoke members22'may be of any desired number to the end that-the unit reinforcement shall best fulfil its oflioe 'hereinai ter described; the openings 24- however being such as will permit the-concrete to be'easily placed in position around the hu'b, spoke and rim portious of. the device. portion 23' oftlhe devices in the upper portion-"of Fig. 1. areithe rod members 25 (see Fig. and 27 (see Fig. 5.) Which rods extend outwardly. through the flat slab on lines radiating from the axis of the column.

For a. clear understanding of Fig. l. the rods are omitted from 1 the unit devices in the lower=portion of the drawing.

In the flat slab type of floor, it is assumed that a fiat circular plate portion of the slab, fixed t'oa supporting-column, extends out- Wardly 'therefrom in every direction, to the line'ofinfiection of the slab, as a cantaliver;

and that the central portion of the flat'slab p'a-nel lies between and is supported; by the outer edges of such column supported cantaliver circular plate portions. In Fig. 8 are seen imaginary cantaliver beams,.31, passing through the axis of a supporting col-- umn, whose enlarged head is designated 32*, as in Fig. 2, and the approximate location of the line of infiection,'33, of the flat slab has been plotted. The beams li-l'at Z, Z, extending toward adjacent columns rectangularly situated, the beams at Y, Y, extending toward diagonallly situated columns, leaving other beams, 31, extending as at K, tmvard those portions of the flat slab included between the axcs of adjacent rectangularly and diagonally situated columns.

By reference to Fig. 4, a vertical section is shown", taken through the axis of a supp rting column, showing a cantaliver beam, such as 31 in Fig. 8, reinforced by the continuous steel reinforcing members 22, 21, 22 of the unit wheel-like cantaliver device.

If were practical to run rod reinforccn'icnt,

directly over and through the axis of each supporting column, on the lines 31 in Fig. 8, and continue such rod members out through th flat slab on theselines produced. not. cnlyavould the cantalivers themselves be ositively reinforced, but tension stresses in the central portion of the flat slab would be likewise taken care of. This however would necessitate the rods crossing each Hooked to the rim.

other at the axis of the column, causing them to pile up one on another so that the 'ccnter'o'f gravity of the mass of the assembled steel Would be greatly lowered. Since the center of gravity of the steel must be near the surface of the slab over the columns, in order to secure the longest possib'lemomentarm and thereby obtain the thinnest slab possible, such radiating rod reinforcement is impractical.

As will be seen in Figs. 4 and 9, the hub or disk portion, 21, of the unit device is formed of such size and character thata sufficient area of steel is concentrated between the radiating members 22 so that under all conditions, each single 'cantaliver beam 31 in Fig. 8 shall be positively reinforced by the unit members, 22, 21, 22, to

.the end that the composite plate of concrete and steel shall act as a homogeneous cantaliver circular plate. The center of gravity of the hub or disk, 21., is, as seen, near the surfaceof the slab over the column, wlnch obviates the impractical feature referred to above-with reference to radiating rod reinforcement; also, a unit device can thus be fabricated in which the radiating members corresponding to such radiating rod reinforcement are an integral part of one another at their point of crossing, so that. all will act as a unit in the completed. strlu'ture. It would not be practical to make the radiating members 22of a unit device of. such length as to actually cover the entire panel between columns; I therefore prefer tofabricate the unit wheel-like reinforcing devices of such size, that they will approximately cover the column supported cantaliver circular plate; the rods 2.) and 27 extending out through the floor slab. are in reality extensions of the members 22, of the unit device, the member 23, of the device, furnishing a means for transmitting the stresses, carried by the rods 25 and 27 directly into the members 22 and to the coin tral hub member 21. This then furnishes in every direction, a continuous reinforcing member, such as 25, 22, 21, 22, 23. 25 or 27, 23, 22, 21, 22, 23', 27, passing directly over and through the center of the supporting column. This is .a very inn'nn'tant fcature of my invention since the stresses being brought directly over and to the center of the column, the column is-not e'crentrically loaded as it \vouldbe if individual lods radiating tl' ro'ugh 'the slab were merely wrapped around the periphery of the column or if not run in a straight line from such column axis. Not only do the supporting columns of a certain loaded panel receive their proper share of such load, but a continuous monolithic action is produced. portions of the stresses passing out. froi'n'the central disk or hub portions 21, through the branching members 22 into the rods 25 and other supports, y x

As seenin Figs. Qand l, the unit canta;

panels assist the loaded panel and its supporting columns to carry the load, by transmitting such stresses to outer columns or liver reinforcing devices areshown preterably fabricated 1n a dished fashion being inverted in the final disposition of said devices 1n the eombm'ed reinforcement, and to".

gether with the rod members are,- as seen in sectiom a proximately on the line of the catenary. forcing devices, the parts 21 and 23 lie preferably ,in substantially parallel planes, in

order that the connecting intermediate radiatin por'tions 22 may be inclined -or curved 11d thereby more nearly follow the said inc of the catenary.

In Figs. 2 and 3 are seen rod members 25 with the hools; 26 formed on one end for engagement with the rim 23 of the cantaliver reinforcing device as previously stated. The outer end of the rod 25 is seen in Figs. ,1, 2, and 61 passing under the cantaliver device over an adjacent rectangulai-ly positioned column, thereby placing steel in a lower plane over the column head which steel will assist theconcrete'to take the compression. This willact to reduce the thickness of the concrete over the entire floor thereby saving in both cost and weight of the structure.

Tension Stresses exist in-the upper face of the slab between columns on rectangular lines ,due to the deflection there being less '7 than in the center of'the slab because of the shorter span. A very important feature of a my invention is seen in the provision I make for caring for such'stresses. In Figs. 1, 2,

' land :5 are seen the rod members 27 with the hook-26" formed on one end for engagement with the rim 23 of the cantaliver reinforcement as previously stated. The outer end of the rfo'd 27 is bent into the position seen in l igz' o forming an'upper portion 28. The

- rods Q'Yflinked tothe rim 23 of the unit device :radia'te therefrom outwardly, the part '28 of the rod 27 being placed in the upper L60. may act as a true link between all such part or fage of that zone of the floor slab "extending between columns as seen at 29 in Figs. 1,2 and t. These rods in the completed structure as in Fig. 1, therefore care forthe stresses referred to above, thereby preventing cracking along the edges of the panels fromcolum'n' to column. The total crossfsectional area of steel of'all the members 25 and '27 linkedto a rim 23 of a unitd e'vice is aphr oximately equal to the area in cross-se'c'tionof all the'radlating members 22 of such devi'ce,".t0 the end that such device radiating members '25 and 27 attached thereto andfprdducea continuous reinforcement in ever i'djii'ecti'on "around the supporting '65 column. r" A vhrticai' section of a completed n these dished shape reinflat slab taken throughdiagorally situated columns in l ig lz would be similarto the section seen in Fi' 2. omitting the members QStherQinseen t e rod members 25 and 27 out by 'siicheec'tioh would be seen lying near the bottom of the slab similar to those shown in section in theeentral portion of Fig; 4.

In the practical application of my invention, in order that each sutiporting column of a loaded panel shall sustain its proper propbrtionate part of such loading, the rods 25..and 27, While, distributed through the p'a'hels'as seen in Fi Lure Preferably ar ranged so that the inner half of said rods lie nearest the under surface of the flat slab, as

illustrated in the left hand portion oi Fig. l. Where the rod 27 -passes beneath rods 25 and 27 shown in section, which rods are radiating from unit devices over adjacent columns. Similarly as this rod '27, therein seen, passes out into the slab, as shown in the right hand portion of Fig. l. it is slightly raised in order to vpermit the inner half ot the rods 25 and 27;,there seen in section, to pass beneath it." Thus lat-any point in the Hat slab, the steel rods are preferably arranged in the order of their distances from their supporting column. Such Weaving of the rods mechanically binds them together, making them self-supporting between col-v unlns and also preventing displ'aceni'ent during the pourin of the Wet concrete.

To tasteh the ho'oks '26 an'd 26* of the bars 25 and 27 to the rim 28 of the unit device in such-a Emanner that the connection at that point will not be easily *disenga ed during the placing of the concrete as We 1 as to insure that the unit device 20 shall act as a tru'e link between the several radiating rods, allowing no slackness in the complete tensi'l'e reinforcement, I may employ 'vari'ou's methods such as electric welding or Wiring the assembled parts, or I may employ the. ring device indicated at 30 in Fig. l. and

. shown in detail in Figs. 6 and 7 wherein a riii 30 is slipped over the hoolr portion 26, an the parts of the hook'26 and the ring 30 driven tight against the rim 23 of the unit device 20. Such other modifications may beemployed for transmitting the stresses from the rods 25 and 27 to the unit device 20 as are broperly a ,part of this invention,

the rods 25 anew may be unprovided with the hook portions 26' and. 26* respectively and merely assembled about the device in the lighter construction work, but I prefer to give an absolutelyrigid mechanical bond or tie to the parts as above described.

At the sides of a buildings'tructure 1 prefer to use half unit devices built into the Wall structure, likewise at the corners a quarter unit device would be employed, the

rod members 25 and 27 being run from these fractional devices to each other and to outer colunihs in inanner seen in Fig. 1.

In Fig. 10. is seen a sheet metal plate With slits 34 and therein, said slits being made on lines radiating from the center of the plate thereby forming the portions 36 and 37 between said slits and leaving a central hub portion 38 and band 39 anslitted. I may however employ several. nonslit-ted portions similar to 39. In the periphery or outerband of the plate are made the U shaped slits 40 thereby forming a lip 4-]. The parts3t5, 37 and -41. are now twisted or bent as seen in Figs. 11 and 1:! thereby producing openings 42. 43 and --l"-lin the entire plate structure, the lip 41. being struck up for the purpose hereinafter set forth. During the process of manufacture 1 pret'er to term the plate structure in the inverted dished fashion seen in Figs. 1.2 and 13,

vl n Fig. '13 are seen the hook portions on of the slab rod reintorcement engaging With the unit structural device through the openings 4A, the lip 4-1 is then driven down upon the hook 26 as seen at- 45, thus firmly attaching the rod member in the desired position. The edge of the unit device may be folded or otherwise thickened as seen at 4-6 which will impart extra strength and stitli'- ness at the .rod engaging parts.

The unit structural reinforcing device seen in Figs. 10, V11, 12 and 1 being a modification of the wheeldike unit device seen in Fig. l), is adapted to be used in lieu thereof, and is n'cferably made as seen in l ig.

I v n 10 troma rectangular or square plate, in-

which event it would be placed with the corner parts extending to aid the columns diagonally disposed to the column over which it is situated, thereby substantially occupying the position indicated by the plotted line of inflection seen in Fig. 8. By the expression cantaliver circular plate used by me is meant that portion oi a column supported concrete flat slab, included within the line of inflection, Ill"). 8, the word tll'cllltll' not being used in its strict sense. The openings 42 and 4?) like 24 in the device-20, Fig. i). permit the concrete to flood around the spoke members 36 and 37. the hub member 38 and the bands or rims 3i.) and 4.6; also vertical column reinforcement. may readily pass through such openings 24 and 42 of the unit devices. Such other modifications may be en'iployed a. are within the scope of the appended claims.

l-laving described my invention, what I new claim as new and desire to secure by Letters Patent is:

.1. .ln a column supported concrete tint slab or girderless 'tloor structure, a rein.- torcementcomprising an inverted solid steel, dished shaped plate ouunit reinforcing device, horizontally disposed over and concentric with the supporting column,

openings in said device, the parts remaining between said openings thereby forming a central portionintegrally connected by intermediate radiating portions witha surrounding band portion, situated in a lower parallel plane, said band-portion lying within the slab without the column, said reinforcing device therebysubstantially covering the. column supported cantaiiver circular plate portion of the slab.

2. in a column supported concrete fiat slab or girderlcss lioor structure, a reinlorcemeni comprising an inverted, solid steel, dished shaped plate or unit reinforcing device, horizontally disposed over and concentric with the supporting column, openings in said device, the parts remaining between said openings thereby forming a central portion integrally connected by intermcdiat'e'radiating portions with a surlying within the slab, Without the column, said reinforcing device thereby substantially covering the column supported cantaliver circular plate portion of the flat slab; and members connecting with said surrounding band portion of the device, extending outwardly therefrom on lines radiating from the supporting column, some of said radiatlug members extending toward and through those portions of the slab lying between adjacent. outer columns, and the remainder of said members extending into those portions oi" the slab over such adjacent outer columns.

:3. lhdntorcement for acolumn supported coin rctc liat slab or girder-less floor struc- 'ture. consisting of a number of inverted solid slcel, dished shaped. plates or unit rcinl'orcing devices, each device being horizontally disposed, in the slab, over and concentric with a supporting column, openings in each of said devices, the parts of a de- 'vice remaining between such openings constituting a central portion integrally connected by intermediate radiating portions with a surrounding band portion situated in a lower parallel plane, said band port-ion lying within the slab without the column, said reinforcing device thereby substantially covering the column supported oantaliver circular plate portion of the slab; and. outer rod members connecting with said surrounding baud portion of the device, extending outwardly therefrom through the bottom of the slab on lines radiating from the supprn'ting column, some of. said rods tern'iinating beneath the unit devices over adjacent outer columns, and the remainder of said rods being bent at their outer ends into the top oi the slab portions included bet-ween opposite outer columns.

-t. A rcint'orcemcnt tor column support.- ed. concrete cantaliver circular plates. comprising a metal plate, slits therein radiating from a central non-slitted portion, and band rounding band portion, said band portion pox-firms in said. trill portion, to by means said slits; these siitted parts having twists i or bends thereby fomnmg opei'ungs Within said plate.

A. perforated unit reinfoii-cing device for concrete construction complislng a. aished shaped. metai. plate having a cen- 'tmi porticn iintegraiiy cuni'zootmi with $111 rounding band or rim portions by interme-' diate portisns formed by slit-ting the plate on lines radiating from the central p rtion, the said intermediate portions fimnms,

V. MCNUTT.

having twists or bends thereby formlng-openmgs 15

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