|Publication number||US2132220 A|
|Publication date||Oct 4, 1938|
|Filing date||Aug 29, 1936|
|Priority date||Aug 29, 1936|
|Publication number||US 2132220 A, US 2132220A, US-A-2132220, US2132220 A, US2132220A|
|Inventors||Powers Eugene S|
|Original Assignee||Powers Eugene S|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (19), Classifications (12)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Oct. 4, 1938. E. s. PowERs FLOOR CONSTRUCTION 0R THE LIKE F'led Aug. 29. 1936 6 Sheets- SheerI 1 1 Oct. 4, `1938. E; s. POWERS 2,132,220
FLOOR CONSTRUCTION OR THE LIKE Filed Aug. 29, 1936 6 sheets-Sheet 2 /uvenlol Oct. 4, 1938.
E. S. POWERS FLOOR CONSTRUCTION OR THE- LIKE Filed Aug. 29, 1936 6 Sheets-Sheet 3 Egli Oct. 4, i938; E, POWERS 2,132,220
FLOOR CONSTRUCTION OR THE LIKE Filed Aug. 29, 1936 6 Sheets-Sheet. 4
T .1Q f
I, y la l 1 y u H $9 W ZZ Q0 '22 l /ZQZ www 6 Sheets-Sheet 5 Oct.` 4, 1938. E. s. POWERS FLOOR CONSTRUCTION OR THEILIKE Filed Aug. 29, 195s Oct. 4, 1938. E. s. POWERS 2,132,220
FLOOR CONSTRUCTION OR THE LIKE Filed Aug. 29, 193e e sheets-sheet 6 .xm sii R.
Il Il m w atented et. 4,- i938 FLOR CNSTRUCTEN @llt TlEllE lLlllllE Eugene S. Powers, Haddontield, Ni Ji, Application August ze, icas, senat um. cette et claims. (ci. 'z2-vi) The present invention relates to improvements in door, roof and deck structure and the like that consist of concrete or other non-metallic slabs on the' upper :danges or chords, of metal members, such as jolsts, beams, girders, trusses and the like. Such slabs and structures are herein conventionally referred to respectively as concrete slabs and as floor structures of joists, beams and girders. n
A purpose' of the invention is to increase the strength of iloor structure of the type` indicated by novel means for insuring against slip between the adjoining surfaces of the top chords of structural members and of a sab or slabs supportedv Vby thechords A further purpose is to provide a seriesof transverse top cleats-at intervals along the top chords of members that support concrete slabs in order effectively to prevent, or support, the slabs from movements with respect'to the chords longitudinal oi" 1 the chords, preferably making the cleats` progressively nearer tgether and/or larger toward the ends of the chords than nearer the middles thereof.V
A further purpose is to provide top cleats at intervals along the chord members'of joints, etc., or the like that `support concrete slabs, with considerable upwardextension into the'concrete and `with longitudinal extensions to laterally overlap or overhangAshe chords.
A furtherpurpose is to connect cleats located at intervals along. chords by longitudinally extending metal bars spaced above the chords` and at' opposite sides of the chords, using the longi- `1tudinally extending bars and transyerse cleats te provide effective and unitary connection between thc slabs id the chords of the structural supporting'mem rs, and preferably also, using the bars for the support and spacing of other reiniorcing bars of the slab, and/o1' for permanent or temporary support of centering between the chords oi successive joists.
nd'furtherrrdrpose is at intervals to cross connect alined cleats of different joists, providing cleats on diderent joists with common lateral bracing.
A, rurther purpose is to extend cleats sumcient-z ly `aburre the chords to provide gauges of fthe thickness of the slab. f
A further purpose is to secure sleepers or other floor supports by means' of the cleats to the cherds oijoists.
' d further purpose is to project cleats beyond.
the lateral edges of the chords, and to use the Y' the notches.
overhanglng portions oi the cleats for securing centering.
A further purpose is to notch the tops or lateral edges of the cleats and secure longitudinally extendingrods inthe notches by deforming part 5 of the walls of the notches or driving wedges into A further purpose is to construct cleats of angle bars which are either integral or assembled.
A further purpose is to space cleats progres- 10 sivelymore widely from the end of the span to the middle of the span and to limit the maximum spacing to a distance that is not greater than the slab can safely stand as a strut between cleats conservatively considered as 12`times the 15.
thickness of theslab.
- Further purposes will appear in the specification and in the claims.
I have elected to illustrate my invention by a few forms only as applied to a number of diifer- 20 ent structural metal joists,A girders and beams,
but have selected those which illustrate particularly well the principles involved, and which are practical and eilicient in operation.
Figure 1 is a. broken top plan of :door struc 25 ture embodying a desirable form oi my invention. The view shows one-half of the span of two joists', showing on one joist a slab that conceals all but two of the cleats, the concealed cleats being shown dotted. The twocleats that come to the 30 top of the slab to act as gauges are shown by solid lines. The other joist is shown without the slab to disclose the cleats, slab reinforcement bars and top of the joist.
Figure 2 is a front elevation of Figure l, show- 35 ing in side elevation a joist of the Maclldar'type,y supported on astandard rolled I-beam.
Figure 3 is afsection of Figure 1 on the line 3 3 thereof and to enlarged scale.
Figure d is a section of Figure 3 upon the line 40 d-d thereof and showing'cleats, slab reinforcing bars and removable centering.
Figures 5 and 6 are enlarged views ofthe cleats pf Figures l to d, Figure 5 being an end elevation 5 or Figure 6 and Figure 6 a half-length face elevation of a. single vcleat that is intended to be suitably symmetrical with respect to the center line of the joist shown in dot and dash in Figure 6.
Figures 7 to l2 are enlarged views to show the 50 'II valsbetween cleats of the Vtop of a slab to act as an and bottom chordsformed of Figure 8 is a section of Figure '1 taken upon tho line 8-8 thereof.
Figure 9 is a fragmentary bottom plan of Figure 8 in the position indicated by the line 9-9 of Figure 8.
Figure 10 is a fragmentary top plan of Figure 8 in the position indicated by the line iii-lil of Figure-8. 'i
Figures 1i and 12 are respectively fragmentary sectional elevations, upon the lines iI-ll and |2--I2l of Figures 12 and 11, showing the structure of a rectangular cleat such as could be used at the center of the span of the ioist of Figure 7, where the cleat has been extended to the intended top of the slab for use as a termine the slab top. Figures 11 and 12 also show the slab as poured on ribbed lath which act vas reinforcement and centering for the slab.
glrder, Figure 16 being an` end elevation at one f the cleats and Figure 17 a section of Figure 1 taken upon the/lineV iI--II thereof. y Figure 18 is an enlarged scale fragment corresponding to a portion of Figure 1'7 and showing a lock pin in an end of a cleat to hold a reinforcing bar rigidly in position. x Figures 19 to 22 inclusive are enlarged views of cleats made of "fiats or bars of rectangular sections, Figure` 19 being an end elevation and .Figure 20 a section on the line 29-29 of Figure 19.
Figure 21 is a fragmentary end elevation, partly in section, showing a cleat extended ,above the anchor for a floor sleeper.
Figure 22 /is Figures 23 to 25 inclusive illustrate lan applica'.- tion of the cleats to Jones and Laughlin Junior beams, Figure 23 being a two beams framing into a wide flange Carnegie Figure 24 is a section of Figure 23 on the line 24-24 thereof, showing the Carnegiebeam as a girder', the slab optionally to be poured or formed on a metal sheet to )be left in place.
Figure 25 is a section on the line 2st- 25 .of Figure 24. Figure 26 is a plan view showing cleats applied to a 6 inch H-beam.
Figure 27 is a front elevation of Figure 26 showing in side elevation a half-span of a beamwith a temporary support at the middle.
Figure 28 is a section of Figure 27 taken upon the line 29-28 thereof and showing removable centering supported on the lower flange of the Ilil-beam.
Figure 29 is a,section of one of the H-beams showing a portion of the slab on topl of it land showing one4 way of protecting the beam to meet requirements of mst-,class "fire-proof construction. l
Figures 301md 31 arev fragmentary elevations showing my cleats applied to a joist that has top also' showing a lateral brace to be/used at interdiiferent ioists.l Figure gauge to dea section ofvF1gureL21. take upon 4the linev 22-22 thereof.
plan view illustrating that will develop the such as concrete poured in place,
`angles and bars,
` and loading. The
sectionofIllgureSOtakenuponthe' Figure 32 shows a case where removable centering laterally overlaps and is wedged upwardly against the outside legs ofthe topchord angles to avoid the need for ing\that will be required if the centering is flush with the top of these angles.
Figure 33 is a section of Figure 32 taken upon Vline 33-33 thereof and showing the lateral brace for joists embedded in the slao.
Figure 34 is a fragmentary section, generally similar to Figure 32 and shows a case where the removable centering has been formed and placed to raise the bottom of the slab above the top of the ,lateral brace made high enough to bring the bottom of the lateral bracing members flush with the bottom of the slab.
Similar numerals refer to like parts in all gures.
Describing in illustration and not in limitation and referring to the drawings:-
It has. already been recognized that timeV strength of iloor structures that include concrete slabs upon Joists, beams and girders, can be increased by securing connection between the slabs and the structural members, so that .the slabs increase the areas of the compression danses of the joists, beams, or girders. for example, that it is generally economical in unitary, or composite rloorstructure to use concrete and metal respectively for supporting the compression and tension stresses in the unitary structure.
' Reference is made, for example, to an article on Shear spiral for composite steel and concrete slabs, lin the Engineering News Record of January 10, 1935, and to United States Patent Nos. 1,885,883 and1,936,14'1,to Howard F.. Young.
I believe the known methods oi.' supporting thek adjoining surfaces have `disadvantages which lintend to correct in my present invention.
The shear spirals shown -in the Engineering News Record are not adaptable to slabs of the thickness commonlyused on light ioistsFurthermore suchspirals cannot take up the full horizontal shear developed. -betwe'e'n the slab and the beam under uniformly distributed loads full working lstress oi' either the slab-or the beam. My invention overcomes thesehr limitations. Furthermore the "shear spira can only be used in a plastic material only insuch slabs but in slabs made of preformed units such as brick or tile which are Iald on centering or in slabs made of long tile or of longpreformed'slab units,'made like short plank that will span from joist to ioist .avoiding the use of centering of any kind.
The prongs" shown in the Young patents have close fitting of the center- It is already known,
whereas my the following limitations that my invention overl comes. The prongs that are formed by shearing and bending the top flange at intervals' reduce the strength of the composite structure besides involving an unnecessarily expensive process of manufacture. The "prongs" lso formed are necessarily limited in their resistance to bending -and horizontal shear. In other words they cannot be designed to 4meet any condition of span "prongs made of a continuvthe ribs on the self-centering. f
aisaaeo ous deformed strip represent a very expensive way of attempting to solve the problem. I aim not only to prevent slippage at the adjoining surfaces between the slab and the joists, beams, girders, or trusses, but also to render available a method of spacing the means of preventing slippage, my cleats, that will give the exact number of cleats required, thus saving material and labor.
The slabs between the cleats function as a series of struts; therefore a safe slenderness ratio,
must be established for the slab, where l is thedistance between the cleats and tis the thickness of the slab. I consider a slenderness ratio of 12 very conservative for concrete slabs reinforced with bars.
I can extend my cleats beyond the edgesof the members to which they are attached to increase their bearing area or to provide means for suspending the'centering from the members, joists, etc. c The spacing of the cleats will depend upon the distribution of the load over the span, whether uniformly distributed, concentrated, or a combination of both, as well as upon the amount of load Aon the joist, etc.
.'I'hecleats can be varied in design to suit the force coming on them or they can all be of one design for a member uniformly loaded, `with the spacing varied to suit the distribution of the horizontal shear.
, The adaptability of my invention is shown not only by the foregoing but by the following uses to which it is put:-
'I'he cleats serve to hold the slab reinforcing bars in their proper position by means of one or two longitudinal bars run between and attached to the cleats, to which longitudinal bars the reV inforcing bars are attached in thebusual way. These longitudinal bars running between and attached to the cleats`also serve to bind the slab to the cleats and throughthe cleats to the joist, etc., thus preventing the'slab from buckling up from the joist when the floor is supporting heavy concentrated loads. n
When self-centering having uniformly spaced` ribs is used with joists, etc., provided with my cleats, it will. be desirable to have the cleat spacing vary by an amount equal to the spacing of The cleats can beI used as a means of attaching the lateral bracing required by floor systems using light metal joists. They can also be used as anchorages for floor sleepers.
liurthermorel I aim to have the bearing faces off my cleats extend up substantially at right angles to the top chord, or ange, of the joist or other structural member to which they are attached. This is done witnthe object of having the bearing areas of the cleats substantially at right angles to the forces to be resisted by the cleats. For .the same reason the faces of the` cleats are placed onthe joist, etc., substantially at right angles laterally to thespan of the joists. 'The bearingface's of the cleats have their areas scientifically determined yfrom the pressures they will have to resist and their shapes and dimensions, vertically and laterally, determined from their areas in accordance with the particularcorrelated purposes for which the cleats are being designed. i. f
It should be understood that a' slab of any material capableof supporting a roof or floor load between its supporting members is a source of potential strength to these members in proportion to its compressive strength and its modulus of elasticity in compression. li proposeto utilize this compressive strength in such away as to develop the maximum strength of the composite structure, or any desiredportion of the maximum strength; the way is by the use of cleats.
In this way it is possible for me to produce floors which are thinnerin proportion to the span, and also floors with greater load capacity for a given span in proportion to their Weight and thickness. By my invention the slab is so connected to its supporting members that the composite structurefunctions as a unit under flexure. To accomplish this result, the stiffness of the cleats against bending, the yresistance of i the cleats to shear, the' security of attachment of members as the floor, roof, etc., deiiects underl any system 4of loading.
'I'he cleats also hold reinforcing bars in their s proper positions during pouring of .the slab if it is poured in place or during laying of the slab if preformed bricks ortiles are used. The cleats provide points of attachment for lateral bracing concealed in the slab. The cleats will also act as gauges for the thickness of the slab. Re movable centering may be held in line with the top chord by the cleats. The centering may also be held by the cleats against the sides of the top chords so as to laterally brace the supporting members while the slab is being placed` and hardened. Floor sleepers can very conveniently be anchored to the cleats.
Each cleat must contribute bearingand shearf ing area and section modulus requisite to transmit the forces which it encounters to the supporting structure. 'The prior art devices referred to, function by supplying bond and tension areas like inclined stirrups.
By a cleat l intend to designate any stiff projection which functions as a cantilever supported on the upper chord., It may be of one piece or several pieces as in the case of a bracket.
The maximum strength from the composite beam can only be developed `when its elements are so proportioned that the finished beam behaves like a one-piece metal beam under flex'ure. To make the composite beam sofunction, we must know the relation n of the modulus vof elasticity of the metal in compression, Em, to the modulus of `elasticity of the non-metal in the compression, Emu-m Em n -f Enonfm Knowing the value of n,I the non-metal compressionvarea of the slab'can be converted into its equivalent metal compression area, and the working stress thereon determined in ,terms of metal stress by multiplyingthe working stress of the slab, fc, by n.v After this' conversion of area it is possible to find the moment of inertia o i the composite 'Ihe next step is to nnd the value. per unit length of the beam, or the increments of pres- 'sure which the slab m'u'st transmit to the beam.
, These increments of pressure constitute the horizontai shear between the slab and each beam which the cleats must resist. Comparison of my cleatswith the prior lart devices' above referred Cto in accordance with the method of computation just outlined has shown that my cleats 1 are much more efficient and more adaptable to u on long and short spans, as do n span. Cleats 42 and n bars bent diagonally up slab to act'as -gauges in screeding the concrete.
, the ends of pieces In these ilgures the top chord 43 andthe bottom chord 44 are both formed oi.' angles. The web members 45 are formed of continuous' round and along the angles. Near the end of the span additional web members 4t, comprising rectangular bars, are used to give needed extra section to the web members at this portion `of the span.
3 The joist is shown bearing on a standard I-beam 45 ureathebarsu 50. tension 65 InFigurethe cleats `4i have their' 00 positions.
-foruseiniining m the cleats u, nana 4 shown in Figures are received in .notches 52 dn -the sides of the 4iwproiect beyond 41. The dot-and-dash line 48 represents the top of the slab.
It will be `noted that the spacing of the cleats" 4| .is rather close near the beam 41, and beu. comes progressivelyv wider toward the center' or Athe span where the .shear for a uniform load is lower than near the beam' 41. y
-, Reinforcing bars'49 pass throughvand attach 42' substantially as 5, 6 and '7, where the bars 4l cleats. Prong portions Il may be hammered down to hold the bars in place as shown by the dotted 'line in Figure 6'. As indicated, Figsupport the cross bars 50 and also serve to prevent the slab from. lifting .slightly from the j oist when the slab is deflected bycbncentrated loads. The high enoughfin the by virtue of the height of bars 4l above the upper chord. The cross-bars 5| preferably are wired to the bars them from being displaced during pouring of the slab. The wiring is shown at 5l'.
tops curved outwardly at 53, the better tointerlock vertically with the concrete and the better to support the-chord and concrete structures in unchanged relative 3 and 4 are shown removable centering 54 on which toform the slab. The cleats the sides of the chord both to present greater surfaces to the concrete and the centering I4 up with the top face .of the chord, as seen more clearly in Figure. l'nliguree3and4pieces5iare shown spanning, from joist to joist to supiiOrt the centering I4, the pieces 5I being supported 51 at the tops of pieces 56, the wedges being used to force the centering up tightly against the under surfaces of the cleats and to hold it securely.
'rne metal ribbon te, rim s mac, nto
down between and bars I4 are positioned slab to function as negative 49, thus preventing notches in the ends of the in the shop on top 61 is shown on top of tends to the `standard i .s. The web members 45 and ,as described for Figures 1 to 4 inclusive.-
This ribbon can be placed of the web members iiushv with the 'top of the chord angles and mayhave its ends welded to the end cleats.
In Figures 5 and 6 are shown weldsll that hold the cleats to the top chord angles 42.
In Figures 'l to 12 the cleats 4i'. are rectangularv bars .welded at 59 to the top chord o!A the Joist. The.l cleats are shown at top chord and web bars, place on the chord. Cross pieces .Il supporting the centering 54. are shown suspended nfrom the cleats by bars 4! and wires il. These wires, as shown in Figure 9, pass through 55 and openings in washers 6l on the under side of pieces il. The'wires Il are` passed around bars 4l and madesecure by twisting infront oithe cleats, Figures 8 and 10, and the washers top chord angles.
but they can be at' any of the span, not shown. 'Ihe joists in Figure I rest on a masonry Il.
y In Figure 8 a ceiling nstruction of metal lath and plaster on is indicated by dotted lines BB. This is a common construction. Any' type of ceiling construction can be used that the occupancy oi a building may require' for protection 'from tire.
In Figures i1 and 12 ribbed lath seit-centering generally poured on ribbed lath light metal joist construction.
If the concrete'or mortar is properly designed.A mixed, and placed on the self-centering it will develop considerable stre ilange. In use with my cleats the self-centering would -be slit or punched between its ribsat It to pass the cleats, as illustrated in Figures 11 and i2. The cleat 422 oi Figures 11 and l2 exseli-centering in of the'slab thickness. -Bars when used with self-centering serve as. "shrinkage bars and to tie `the slab to the joists through the cleats.
In Figures 13, 14' and 15 are shown joists of special design framed into design; which girde'ris supported on a column 41. This column is shown braced laterally by an I-beam'which also supports the floor slab. The top chords Il oi the joists are illustrated as made or standard .Jones and Laughlin chan- 51 nels and the bottom chords 1l made 'oi two It ere 1b cleats 4l' and 42z on the joist are shown es x.- tanglllar are notched to receive the bers 49, as shown in Figure 6' for the affine-type cleats. I
In Figure 15 vthe joist is shown of reduced depth .toward the lends topermit a thicker 'slab to be g formed at 44' over and near the girder -1i in-order that the slab may functionl better as a compression ilange ifor the girder in compodmteiloors thatwinclude joists and slabs that are too thin for this purpose. Bars 12 are suitably supported 1 on and wired to the bars 4l and run'transvereely of the joists. l
InFigures 13 and 14 the cleats 423, on they girder 1|, having an upper chord 4l and a web 452, are built up a's heavy brackets since the the intersection oi the l0 openings in l5 el are shown securedto the 2o vends of pieces I! by screws e2, Figure 9. The
used toward the middle g5 type 0f ceiling so the joist. Theslab is 35 gth--as a compression 4g top of the-slab to act as a gauge 45 a girder'of special M bars or flats, see Figure 15. 'Iheenlls o of these cleats aisaaao forces in the slab acting as a ilange to the girder v are much greater than the forces in the slab on` on the gircler produces the effect or' such a load.
Change in spacing is preferred to using heavier cleats near the points of support than toward the middle of the span.
Bracket pieces 'it are provided to adequately and economically resist the overturning moment on the individual faces of the larger cleats. The face piece 'i3 is preferably on the side of the vcleat toward the center oi" the span and the bracket piece 14 on the side toward the nearest end. The face piece 13 is given a section sumcient to resist the maximum bending moment on the face piece which may be at the brackets from the cantilever portion of the face, or between the brackets. The welds 15 are designed to take the tension produced by the overturning moment, and the welds 'l5' are proportioned to/the shear that is to be resisted. The welds 'I6 connect the face and bracket pieces. v
In Figure 17 the face piece 'i3 of bracket 423 has'notches at its ends, which notches are of different shape from the notches 52 inFigure 6. These notches which are to receive the bars 49', are placed-to locate the bars 49' so that the bars 49' hold the cross bars f8-near the top of the slab so -as to enable the slab to cantilever out from the girder. In Figure 17 the bars 49 are locked in position by wedge-shaped keys 19 which are driven lunder the bars 49 so that the ends of the keys will curl up back of the bars, as in Figure 18, showing `an enlarged View of notch 'I1 and key 19. Thekey 'I9before it has been driven in is shown by dotted lines, and afterl it has. been driven in under the bar 49 is shown by solid lines.
In Figures 19 and 20 is shown a cleat lll3 made of a bar of rectangular cross section. In Figure 20 two diierent ways of treating the ends of cleats are shown, the notches 52 to receive the 'l bars 4 9 vbeing generally similar to those shown in- Figure 6 and the prong portions 5| beingdriven down as in Figure 6.
In Figures 21 and 22 are shown a cleat M4' used also as an anchor for a sleeper 80 to which the wood floor 8l is nailed. The sleepers are leveled by wedges or spacers 82 and secured to the cleats by lag screws 83. Cleats 4H are reduced in width at their tops to save metal.
In Figures 23, 24'and 25 are shown cleats 4|5 made of rectangular bars on Jones and Laughlin Junior beams 84 that are framed into a wide flanged Carnegie girder beam 85. The cleats are spaced for uniformly distributed load with the closest distribution near the ends of the span. The space between successive cleats increases as the horizontal shear between the slab and beam decreases, with the cleatspreferably located to transmit the same amounts of shear.
In Figure .24 the cleats 42 respectively at the center of the span, at the quarter point, and at the ends of the beam 84 are shown extending to the top surface of the slab to serve as gauges for use in screeding the concrete.
11n-Figure 25 the cleats are shown wider at the top than at the bottom f or a'better gripping of the slab; bars 4S have'not been shown. In Figure 25 the tops of the ribs on self-centering t6 areindicated by a dotted line; also the top oi the slab 4t is shown by a dot-and-dash line.. The Seli-centering can be a solid metal sheet with ribs of height and spacing to suit thespan of the slab and its load. A ceiling is indicated at t5'.
in lFi; res 26 150.28 inclusive are shown. cleats M2 that are similar in form and character of l spacing to the cleats d2 in Figures 13 to 17 inclusive, except that the cleats 422 extend to the top of the slab to act as gauges in screeding the concrete, while the cleats il l2 do not extend to the top of the slab. The cleats in Figures 26 to 28 inclusive are suitably designed forK a 6-inch 20- pound l-l-bea-m and ldevelop-til inches of 4-inch thick, 200G-pound concrete slab when the span is 17 feet, 3 inches. The beam bears on masonry 'walls 65, only one of which lis shown.
:Figure 26 shows a half span of beam 86 in plan and Figure 27 shows a half span in side elevation. A temporary support tl is indicated in the` centerof athe span for use until the' slab develops sumcientstrength to permit the removal of the temporary support. The beam in this case would not be capable of supporting the structural load f before the `slab sets if the temporary support were not used.
In Figure 28 the wood centering dd is shown supported on wood joists 89 that span betweenl lower ilanges M of laterally successive beams 86. Wedges 9i) may be driven between the ends of the joists and the webs of the beams.
In Figure 29 the beam is shown encased with ilreprooflng 9i. This iireproong may be in the [form of tiles of any material having the required fire resistance. Plaster is shown at 92 over the tiles. The beams may of course be protected by concrete poured around them in the usual way.
In Figures 30 to .t5-inclusive, lateral'bracing 93' is shown cross-connecting alined cleats 4| and 4l of successive joists at one set of the cleats. This bracing can consist of a bar, or a small channel, or a small angle against the faces of the cleats and is attached to the cleatsby any suitable means as by nails, pins or bolts 94 passing through openings in the cleats 4| and bracing. Figure 33 shows the relation of the lateral bracing 93 to the top and bottom of the slab. The reinforcing rods 49 are omitted in FiguresSO and 31. i
Zin order to illustrate that the cleats toward the end of the span may be of diierent construction from those at the center, and preferably stronger than those at the center, with uniform cleat spacing, I show in Figure 30 a bracket cleat M2 toward the en'd of the span.
Figure 32, to larger scale than Figures 30 and 31, shows the chords made up of angles 95 and bars 96 between the angles,`which .bars serve to locate the center of gravity of the chords 43 and 4t further from the neutral axis of the joist and also give the required sectional chord area with lighter angles than would be otherwise possible, which facilitates spotwelding. The bars 96 also ll the space between the chord angles and at type of ceiling, not newl is not generally used on light fabricated metal ioists because of its weight, but the increased strength obtained by uniting the top slab and joist by means of my cleats makes it feasible. Such pre-cast ceiling slabs produce a more fire-resisting construction.A Cleats Il" can be used on the lower chord to engage these ceiling slabs near the support of the Joists to resist negative bending moments. "I'he centering of Figure 32 is similar to that of Figure 3.
Figure 34 is generally similar to Figure 32 except in the following points. The centering I is thicker in Figure 34 than in Figure 32, having its edges 99 beveled and the lower side of the centering set flush with the lower side of the outstanding legs of the top chord'angles 95. This elevates the bottom of the slab above the top of the chord angles except for that portion immediately above the angles where the slab becomes thicker. Elevating the slab in this way increases the moment of inertia of the composite structure, giving a correspondingly greater section modulus.
In Figures 32 and'34 the cleats 4l6 that receive the lateral'bracing 93 are shown. They are higher than the cleats which do not receive the lateral bracing. This is shown more clearly in Figure 35. The heights of other cleats are preferably determined by the area required to give the necessary bearing on the slab.
As the structure of my invention diifers materially from devices available in the art, I will give an example of the application of my invention to a Jones and Laughlin Junior inch, 8.96
pound I-beam on a 20 foot span without temporary supports. In this instance the beam will be required to support all permanent dead load by itself. The extra strength to be derived from the slab will only be available for load coming on the iloor after the slab sets.
lWith the beams spaced 2 feet on centers and supporting a concrete slab 2 inches thick, the vpermanent dead load will be 59 pounds per lineal foot. The bending moment will then be 59 X 201:-8 :2,950 foot-pounds Istress is limited to 18,000 pounds per square inch;
that is, the sum of the extreme tension stresses produced by the loads Von the beam both before and after the slab sets should not exceed 18,000
pounds per square inch. Therefore the extreme tension stress available to functionwith the slab is 18,000-4,550=13,450 pounds per square inch. Using concrete having a compression strength of 2,000 pounds per square inch, with Ec--nl where E1 is the modulus of elasticity of steel i compression, Ec is the modulus of elasticity of concrete in compression, and n is the ratio, the area of the slab in terms of steel is 2X24-:-15=3.2 square inches. Kno hing this area, the center of gravity of the composite section can be located and the moment of inertia of the composite section can belfound by the usual formula ((adLi-i) where a is the area of an element of the composite section, d is the distance from the centre of gravity of that element to the neutral axis, or centre of gravity oi the composite section, and i is the moment of inertia of that element whose area is a.
tom of the beam be C2.
Let the distancey from the top of the slab toY the center of gravity or neutral axis of the composite section in terms of steel be C1 and the distance from the center of gravity to the bot- These distances control the relative values of the working stresses, l, the extreme fiber stress under compression of the concrete in terms of steel, and f1, the extreme fiber stress in tension of the steel. 'Ihe same relation must exist between fu and fr as between C1 and Cz. With 'f1=800 15=12,000, and f1=18,000 pounds, C1 becomes 4/10 dl and Cz becomes 6/ 10 d1, where d1 is the distance from the top of the slab to the bottom of the beam, etc. When C1 is less than ir/10 d1, 18,000' pounds is the working stress and when C1 is more than 4/10 d1, 12,000 pounds is the working stress.
In the caseumder consideration, C1=3.7 inches and d1 is l12 inches, so that the working stress' is 18,000 pounds. C2 is .8.3 inches, and therefore the maximum compression on the concrete is 13,450X3.7:-8.3=5,996 pounds per square inch. The moment of inertia of the composite section, '1 90.0. The resistingA moment of the composite section isl 90 13,450:8.3=145,843 inch-pounds. This resisting moment gives a safe load of witnftne beams spaced 2 reet apart the sare "live load per square foot is This safe live load only applies if there is vno ceiling supported from the beam, since the beam =121.4 pounds per square foot supports all permanent dead load before the slab dead load, there is a safe live load of 174.5 pounds per lineal foot or 174.5+2=87.25 pounds per square foot on the beams as used in the prior art without any means of causing the slab to function with the beam in resisting tlexure.
By the use of my cleats, this live load may be increased to 121.4 pounds per square foot, an increase of 39.14%.
The reaction is one-half the total live and dead loads, or
' be transferred to the beams by the cleats between the point where the shear is zero and the reactions. 'This compression, P, equals the area of the slab section in terms of steel, or 3.2 square inches, multiplied' by the average stress on the slab in terms of steel. This average stress is (i. LC where C: is the distance from the center of gravity of the composite section to the center of the slab section. In the case under consideration P is 13,450X2.7+8.3 3.2=14,000 pounds. The value 0f P is distributed over half the span in incre- FEW ments increasing uniformly for a uniformly distributed load from zero at the center ofthe span to a maximum p at the reactions.` The distribution per lineal inch of span may be represented by the ordinates of a right triangle spaced one inch apart. .The area ci the right triangle is P, and l iawox2' W -234 POulldS The force on any one cleat equals the average ordinate between the cleats multiplied by the distance'between the cleats. If the spacing of the cleats be lxed arbitrarily, the average ordinate can be 'determined and the force to be resisted by each cleat can be calculated. However, generally the best practice is to keep one size ci cleat throughout and increase the cleat spacing as the ordinate p reduces. To do this, it is necessary to nx the size of the cleat and determine the force that it will resist. To ilx the iii-st space Vfrom the reaction, divide this force byfp. Then determine the second space from the reaction by using the ordinate that is 1% times the first space from the reaction. For the third space use the ordinate that is 11/2 times the rst space plus theY second space from the reaction. Proceed thus until a space is obtained that is l2 times the thickness of the slab. 'Ihen use this space as a maximum for the rest of the distancepif any, to the center of the span. This method `'is quite accurate, erring slightly on the side of safety.
Applying' these rules to the present case, we must iirst determine' Athe bearing area of the cleat. The upper lange of. the beam is 2.69 inches Wide. Based on 400 pounds per square inch safe bearing value, the preferable area of the cleat is 2.625 square inches. Therefore the cleats need not be'more than 1 inch high. Using 400 pounds per square inch safe bearing value for concrete, the force to be resisted by the cleat is' 2.625 400:1050 pounds. The rst space is 1050-*234: inches. The distance to the second average ordinate is 4.5 i.5=6.75 inches. The average ordinate for the second space is This dgure divided into' 1050 gives the second space. All of these factors are constant except the value in brackets, so the constants may be reduced to 1050 120+234=about 538, erring on the side oi.' safety. .Then the second' space is im-e,
Therabove calculation may be summarized in a formulm- :4.75 inchesy EL 1pulpit@-SlsZ-s. Where F is the force in pounds which one cleat can safely resist, L is the length in 'inches of vertical 'shear is zero, and continuing to' the' two cleats whose spacing is in question.
For approximate work, erring on the side of safety, the quantity 1/zSi may be neglected, especially' in nding the spacings near the center of the span. In that case it will be seen that the spacing between any two adjoining cleats other than a 'pair at one end oi the span is approximately a constant (in this instance 538) divided by the distancey from the center of the span to the approidmate center of the space being determined.
There will be 28 cleats with ll inches space at the center of the span.
The maximum overturning moment to be resisted by any cleat is l050 0.5=525 inch-pounds. Using this as the maximum bending moment with an extreme fiber stress of 18,000 pounds, the required section modulus of the cleat is 525 bei2 ic,ooo'oozgz"5 where b is the assumed length of the section resisting bending and d the required depth in inches of the section resisting bending, that is, the thickness of the cleat.
The cleat should be attached to the beam by welds on each side along its length. In designing the Welds the shearstress at the throat of the Weld used for the calculation is 11,300 pounds per square inch. The tension through the throat of the Weld is taken at 13,000 pounds per square inch in the calculation. The shear requires a Weld area of l050:-11,300=0.093 square inch. The Welds stii'len the cleats in bending so that the thickness of the cleat can be 0.25 inch. Using this 0.25 inch as the resisting lever arm, the tension on the weld will be l l050 0.5`+0.25=2100 pounds 'Ijhe Weld area required for the tension is 21oo+13poo=crz squarey inch Half the Weld area required for shear is placed on each side of the cleats. Therefore the throat area of the weld is 34- o.17=o.z17 square inch If the weld is run the full width of the flange of the beam, say 2.625 inches, the throat Width ci 4 2, Cz- 8.3 195,180 mch-pounds- 8 where w is the total safe load and l the length of the span of the beam in inches. Then jesmoxs 5,505 pOUiildS.
The reaction is 3253 pounds and the permissible reaction 8240 pounds. Thesafe load per lineal 'foot is 6506+20`13253 pounds. subtracting from this the 59 pounds per lineal foot dead load, there remains 266.3 pounds per lineal foot live load, or 266.3+2=133.15 pounds per square foot live` load.
45.9 pounds per square foot-or 52.6%. This is a 13.46% gain in live load over the case in which the beam has no temporary supports.
This maximum total load on the composite beam. will produce a deiiection of only 'I'he permissible .live load deflection is 20+30=0.66 inch 5X 4,670 X 240s 384)( 29,000,000 X 39.01
There is then a 41.51% reduction in deflection due to the cleats'as well as a 52.6% increase in live load. i 4
It will be evident that the benets oi my invention may be obtained with any construction of metal shapes covered or enclosed with concrete, or other material as well as without such protection.
It will be evident thatan important featurev of the invention vis the use of stiiv projections called cleats, disposed on the chord of the metal support to engage with a non-metal slab. The cleats perform the functionl of transferring to the beam', increments of pressure induced in the slab by fiexure of the construction. A
The particular form of the cleats is immaterial :6.448 inch =0.766 inch .in-the broader aspects of the invention, providing they are stii cantilever members extending generally transversely with respect to the length of the beam, having suiliclent bearing area 'for the pressure to be transferred from slab to beam, etc.,` have adequate shearing area, adequate section modulus and adequate anchorage.
It will also be evident that in the broader aspects of the invention the spacing of the cleats rather than another.
along the chord is immaterial so long as each cleat is capable of withstanding the pressure to which itis subjected at its particular location.
It will also be evident that the manner of connection between the-cleats and the chord is immaterial in the broad aspects of the invention. The cleats are preferably Welded, but they might conceivably be riveted or formed integral kwith the chord.
Of course the supporting member may be of the type commonly designated as a joist, beam,
girder, or truss and no particular -signicance is to be attached to the use of one of these terms For convenience I use the word joist in the claims to include also beams, girders, and trusses. Such membersmay be rolled or fabricated in any suitable shape, section or dimension. Y
It is also evident that the cleats can be used onthe top and bottom chords of the supporting members to assist in resisting positive and negative bending moments in continuous constructions. The cleats may also be used en the chords vof curved structures such as arches, vaults, etc.
By a chord, I intend to include any similar portion of a structural member such as a flange,v etc., or any part of a structural member subjec to compression due toV fiexure.
It will further be evident that I do not weakenv my upper chord by upsetting portions of the upper chord to form projections into the slab.
2,132,220 The safe uve load of the bam itself is only :n.254
Theup'per chord will desirably be impertorate except for the possible bolt holes, etc.
It will further be evident that the longer the cleats are, the less height they will require and consequently the less bending moment they will have to resist and the thinner the cleats can be. The relations of length to height of cleats are lgenerally controlled by other considerations than bending moment.
' In view of myinvention and disclosure variations and modifications to meet individual whim or particular need will doubtless becomeevident to others skilled in the art, to obtain all or part of the benets of my invention without copying the structure shown, and I, therefore, claim all such in sc far as they fall within the reasonable spirit and scope of my invention.
Having thus vdescribed my invention, what 1 2 claim as new and desire to secure by Letters Patent is: l
1. A structure for a composite floor, root, deck system or the like, comprising a metal Joist having cleats secured to it at intervals along its lengthand extending laterally substantially at right angles to and upward from the joist to engage with a non-metallic slab to be formed on the. joist, in which the spacing of the cleats,
in inches proceeding from the ends of the 101st to the centre of the span, when the floor system is designed for a uniformly distributed load, is approximately a constant divided by the distance from the centre of the span tothe approximate centre of the space being determined.
- 2. A structure fora composite iloor or the like, comprising a metal joist having an upper sur.
' face provided with cleats attached at intervals along its length and extending laterally substantially at right angles to and upwardly from the joist to engage with a non-metallic slab to be `formed on the joist after it is set in-piace; in
which the spacing in inches between any two adjoining cleats other than the pairs at the ends of the joist is substantially:
where E'. is the force in pounds which one cleat can safely resist, L is the length in' inches of one-half the span of the joist, P is the compression in pounds produced in the slab by the maximum bending moment on the composite structure produced by the live'load alone, that is, the superimposed load alone, when the ioist is not temporarily supported, and by the total dead and live load when the joist is temporarily supported before the slab is poured or formed, and S1, Sz, S3, etc., are the spacings in inches between adjoining cleats numbering from the end ofthe half span for which .the spacings are being determined and continuing to the two `cleats whose spacing is in question.
3. A .metal-structure i'or use in a composite floor or the like o'f metal anda non-metal slab,
comprising a metal joist having an upper chord l where F is the force in pounds which one cleat can saiely resist, L is the length in inches of yco ' chord.
aisacao moment in the nished composite floor and Si,
S2, S3, etc., are the spacings in inches between ladjointing cleats numbering from the end of the half span 'for which the spacings are being determined and continuing to the two" cleats whose spacing is in question and in which, where the answer from this spacing calculation exceeds the product of the safe slenderness ratio of the slab times thethickness ci' the slab, the spacing of the two cleats in question is-limited to this" product.-
4. A metal structure for use in a composite floor or the like of metal and concrete or ma-` sonry, comprising a metal joist having an upper chord, a plurality of cleats secured to the upper chord at intervals along it, and'extending gen-l erally transversely to the upper chord and above the upper chord into' a slab, in y.which the first two cleats. at an end of the span are spaced by a distance ,substantially equal to the force in pounds which one cleat may safely resist multiplied by the length in inches of one-half the span and divided by twice the compression in pounds produced in the slab by the maximum bending moment.
5. ,A composite floor structure orthe like having a plurality oi-metal joists each of which has a continuous undeformed upper chord, a slab extending across and supported upon the-upper chords and a plurality of individually separate cleats, each presenting a substantially iiat bearing surface to the force that the cleat is to resist, each cleat extendingup into the space occupied by the slah and extending transversely ot the upper chord for the prepondcrant part oi the width oi? the upper chord, and resting upon and 'secured to the top of the upper chord.
v(i. A composite floor structure or the like having a plurality of metal ioists each oi `which has a continuous undeiorrned upper chord, a slab extending across and supported upon the upper chords and a plurality of individually separate cleats, each presenting a substantially :dat bearing surface/"to the torce the'cleat is to resist, each cleat extending up into the space occupied by the slab 'and extending transversely of the upper chordfor the preponderant part oi the width ci the upper chord, and resting upon and secured to the top of the upper chord in which 4the spacing of the cleats, in inches, proceeding :from the end oi each joist to the center-ol its span,l under uniformly distributed load, isl approximatelya constant divided by the distance from the center ci the span to the approximate center of the space^being determined.
7., ln a metal joist construction tor use with a concreteslab, to iormla composite constructiom a nietal, joist having an upper chord vvhich'is adapted to support the slab and a plurality4 oi metal cleatsextending transversely oi the length oi the joistr and distributed alt-intervals along the upper chord', each cleat having an element which is substantially dat, upstanding from the upper chord and extending in length transverse .to the upper chord and having a bracket portion 'which extends substantially longitudinally of the joist, andA engages and supports one side of the upstanding element against overturning rncrnents, the upstanding element and the braclret resting upon and being secured to the 'upper u. ln a metal .ioist construction intended to he used vvith a concrete slab to torni a composite' structure, a nietal joist having an upper chord,
a plurality of individually separate cleats resting upon and secured to the upper chord, extending y transversely of the joist and extending away from the joist into the space to be occupied by the slab and a metal bar extending iongndinailyl of the joist above the upper chordand secured to the successive cleats.
9. In a composite oor structure or the like,
lmetal icists having upper chords, a slab extending across and 'supported by the upper chords, a plurality oi cleats distributed along the upper chord, extending generally transversely to the lengths of the joists and extending above the upper chords into the slabthere being notched ends to the cleats, and rods extending longitudinally of the joist above the upper chord secured in the notches.
l0. In a composite iioor structure or the like, joists having upper chords, a' slab extending across and supported upon the upper chords, cleats distributed along and secured to the upper chords, extending transversely of the lengths ol the joists' and extending vertically above the upper chords into the slab and reinforcing rods secured to the cleats and extending longitudinally of the joists.
11. A, plurality of laterally spaced joists, cleats thereof, a metal bar along and above each side of each joist seated in the end recesses oi thecleats and means at the recesses. fastening the bars to the cleats.
l2. A plurality of laterally spaced joists, cleats recessed at their ends spaced laterally along and individually fastened transversely across each joist on the top thereof, a metal bar along and above each side oiveach joist seated in the end recesses of the cleats and key means at the recesses fastening the bars to the cleats.
13. ln a composite door'structure or the lllre, metal joists having upper chords, a slab extend-l ing across and supported upon the upper chords and a plurality oi cleats distributed along and secured to the upper chords, extending transversely of th'e jcists for at least the iull Widthsy tending across and supported upon the upper chords, a plurality of cleats extending transversely of theupper chords oi the joist for the preponderant part' oi the Widths of the upper chords and exdit dill
tending vertically alcoveA the upper chords into the slab, there being extensions oi' the cleats,
abovefthe slab, door sleepers and means ior attaching door sleepers to the extensions oil the cleats.l
l5. .d plurality of laterally spaced ioists hav- `ing upper" chords, cleats spaced' at intervals along the joists., extending transversely oi .the
.joists and supported upon' and secured to the upper chordsoi? the ioista a metal bar extending longitudinally or each ioist laboveits upper chord and engaging the ends ot and securcd to the cleats oi each joist, centering between the joists and ineens tor supporting the centering frorn said bars.
lo. in a construction for pouring the slab oi a composite door structure or the like, rnetal joists having upper chords, a pluralityoi cleats distributed along the upper chords, secured to the upper chords, extending transversely of the lengths ci the joists for) a distance greater than the widths of the uppr chords so as to project beyond the edges of the upper chords and extending .vertically above the upper chords and 'into the space to be occupied by the slab, centering laterally adjoining the upper chords and Cmeans for holding 'the centering in place up against the projecting edges of the'cleats.
17. In a construction for pouring the slab of a composite floor structure or the like, metal joists having upper chords, a plurality of cleats `distributed along the upper chords, secured to the upper chords, extending transversely of the lengths of the joists for a distance greater than the widths of the upperchords so as to project beyond the edges ofthe upper chords and extending verticallyabove the upper chordsand into the space to be occupied by the slab, ,centering laterally adjoining the upper chords and structure including Wedges for forcing the centering from the joists up againstlthe projecting edges of the cleats.
18. A composite floor including laterally spaced metal joists, transverse metal cleats at intervals along and fastened to the chord of each joist, v
a metal brace extending transversely of the joists rigidly connecting one of thel cleatson one joist with one of the cleats on' another joist, and a concrete slab incorporating `the cleats, brace, and joists into a unitary bondedY structure utilizing the slab as a compression member of the floor. l 19. A composite door structure 'or the like, having a plurality of metal joists with upper chords, a slab extending across and supported upon the upper chords, and a plurality of stiff cantilever cleats separated from one another,
distributed 'along and secured to the upper slab, each cleat at its particular location presenting a bearing area substantially at right angles to the length of the joist, proportioned to the compressive resistance oi' the slab and having a cross section and attachment to the joist capable of resisting horizontal shear and resisting bending Without the aid of the material composing the slab.
20. ,A composite floor structure or the like, having a plurality of metal joists with upper chords, a slab extending across and .supported from the upper chords, and a plurality of stiiir cantilever cleats sepa. ited from one another, distributed along the upper chord, each cleat comprising an angle attachment, one ,arm of which rests upon and is secured tothe upper chord andthe other arm of which extends transversely ofthe length of the joist for a. distance substantially as great as the width of the chord and vertically up from the other arm and from the upper Vchord into the slab, each cleat at its Y particular location presenting a bearing area on its upstanding arm proportioned to the compressive resistance 'of the slab and having a cross section and attachment to the joist capable o! resisting horizontal shear` and resisting bending Without-the aid of the material composing the slab. A
EUGENE S. POWERS.
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US2479475 *||Mar 16, 1944||Aug 16, 1949||Porete Mfg Company||Composite structure with triangular shear connectors|
|US2479476 *||Apr 25, 1944||Aug 16, 1949||Porete Mfg Company||Composite structure embodying shear connectors|
|US2636377 *||Nov 7, 1945||Apr 28, 1953||George Hilpert Meier||Reinforced concrete beam|
|US2994937 *||Jun 11, 1954||Aug 8, 1961||Williams Chester I||Concrete form hardware|
|US3093932 *||Apr 22, 1960||Jun 18, 1963||Lubash Samuel||Floor construction and method of providing same|
|US3158925 *||Jul 8, 1963||Dec 1, 1964||Keystone Steel & Wire Company||Method of making a purlin or roof truss|
|US3527007 *||Aug 12, 1968||Sep 8, 1970||Mcmanus Ira J||Steel joist connection and end connection therefor|
|US4067168 *||Jul 1, 1976||Jan 10, 1978||Hilti Aktiengesellschaft||Connecting element for a composite beam|
|US4189883 *||Aug 4, 1978||Feb 26, 1980||Mcmanus Ira J||Composite system for floor frame members|
|US4598523 *||Jan 17, 1984||Jul 8, 1986||Tolliver Wilbur E||Reinforcement support spacer|
|US7603912 *||Jun 14, 2006||Oct 20, 2009||Weyerhaeuser Nr Company||Method for determining span lengths based on properties of lumber|
|US8529178||Feb 18, 2011||Sep 10, 2013||Nucor Corporation||Weldless building structures|
|US8636456||Mar 13, 2013||Jan 28, 2014||Nucor Corporation||Weldless building structures|
|US9004835||Sep 9, 2013||Apr 14, 2015||Nucor Corporation||Weldless building structures|
|US9267527||Aug 28, 2013||Feb 23, 2016||Nucor Corporation||Weldless building structures|
|US20070289674 *||Jun 14, 2006||Dec 20, 2007||Schulner Thomas F||Method For Determining Span Lengths Based On Properties Of Lumber|
|US20110203217 *||Feb 18, 2011||Aug 25, 2011||Nucor Corporation||Weldless Building Structures|
|EP0369914A1 *||Nov 16, 1989||May 23, 1990||Centre D'etudes Techniques De L'equipement De L'est||Method for joining a matrix material to a functional support, and devices manufactured according to this method|
|WO1990005818A1 *||Nov 16, 1989||May 31, 1990||Centre D'etudes Techniques De L'equipement De L'est||Method for making integral a mass of material with a functional support, and devices thus obtained|
|U.S. Classification||52/334, 52/684, 52/371, 52/365, 52/698, 52/328, 52/326, 52/367|
|International Classification||E04B5/29, E04B5/17|