US1929478A - Floor slab - Google Patents

Description

H. H. BUNKER Oct. 10, 1933.

FLOOR SLAB Filed March 19, 1931 3 Sheets-Sheet l o O m m M ad *i will,

0d. 10, 1933. H H BUNKER wwwa FLOOR SLAB Filed MaIOh 19, 1931 3 SheStS-Shee't 3 Patented Oct. 10, 1933 A UNITED STATES PATENT oEIcE rEoon stan i n Herbert H. Bunker, Jersey City, N. J. j Applicatien March 19, 1931. Serial`ll`lo.'k5rft3,740 16 Claims. (Cl.j72-7G) This invention relates to floor slabs and has for a principal object the production of a floor slab comprising steel and iilling material such as concrete and in which the steel is so arranged as to provide a rigid and strong slab capable of withstanding the effects of concentrated loads wherever applied. Floor slabs are supported similarly to beams; that is, at their ends and sometimes intermediate their ends but they are unlike beams in that they are relatively wide in comparison with their depths. The result is that a concentrated load like the wheel of a vehicle applied at a point between supports causes ilexure in all directions from the point of application of the load and an accompanying tendency to cause dishing of the slab. A constantly recurring error in slab design is attributable to the endeavors oi engineers to produce a slab of minimum weight without giving sufcient consideration to the fact that the large surface area character of a slab requires strength enough in all directions to prevent .excessive dishing. Dishing of a slab results in the rupture of the bond between the steel and the lling material and also affects the life of the slab. Slabs have been produced which are strong enough to resist vexcessive flexure in one direction, as from support to support, but which are not suiiiciently strong to prevent flexure across the slab as would cause disintegration of the filling material. Accordingly, it is an object of the present invention to provide a slab in which the steel construction is such as to adequately brace the slabs in all directions and prevent such flexing and dishing of the slab as would break the bond or crush lling material and to accomplish this in a slab of minimum weight for a given load.

In addition to providing a slab in which the steel is so arranged as to adequately care for forces of tension and compression on its end and upper portions, it is a further object of the invention to provide such a slab as this which is capable of withstanding negative bending movements so as to be useful as a continuous beam over several supports. To these ends the floor slab of the present invention is provided with a steel plate which serves as the lower surface thereo and which has bars associated thereslab with parts broken away sired and-are notused solely for the purpose. of joining the floor grating to the plate. Bywelding the intermediate members at the places they come linto Ycontact with the plate andfloor grating aunitary reinforced steel structure is obtained. Since I prefer the use of bent bars for intermediate members, I have chosen to accompanythe disclosure ot my invention with illuscation andin the claims thereof, setting forth a preferred embodiment of my invention which may be fully understood from the detailed description anddrawings, in which:

f Fig. 1 is a plan of a iioor slab in which partsv are.broken-away t0 show the relation of thebars.

Fig. 2 is a section'on line 2.42 of Fig.y 1. Fig. 3 is a view of the adjoining ends ofthe slabs illustrated .in Fig. 1, with vparts broken away to show Vthe manner of joining. l Fig. ,4 is a section on line 444 of Fig. 1. Fig. 5 is a plan'of another'form of iioor slab with partsbroken away to show the relation of the bars. y

Fig. 6 is a section on line 6-6 of Fig. 5. Fig. '7 is a section on line 7-7 of Fig..5. Fig. 8 is a plan of aportion of another form of floor slab."

Fig. 9 is a section on line 9-9 of Fig. 8. Fig. 10 is a plan ofstill another form of floor toshow construction.

Fig. 11 israsection on line 11--11 of Fig. 10. Fig. 12 is a'plan of a detail showing one mode lof joining the iioor slabs.

Ordinary gratings of bent bars have been used licor slabs which consist of bars such as rails ori angle-irons placed side-by-side and supported by means extending crosswis'e. kWhen suchk iioor 'plate 10 forms the bottom of the slab.

slabs are subjected to concentrated loads the lower longitudinal members are likely to spread from one another and cause destruction of the bond of filling material and its loss` Of course, floor slabs of the character just referred to may be made in such a manner as to not possess the disadvantage stated to a detrimental degree, but Such a floor slab would be of a weight greatly in excess of the slab of the present invention.

In Figs. 1, 2, 3 and 4 I have illustrated one embodiment of my invention in which the steel It is expected that each slab be of such an area as will be suitable for any particular job but, ordinarily, for a bridge, individual slabs will be connected together to form the flooring. Slabs for a road or floor surface of a bridge are laid adjacent to each other and are bolted-or otherwise fastened together wtih proper allowance for expansion. As illustrated in Fig. 1, a single oor slab may extend from one beam 11, across a second beam 12 to'another beam 13.

As may be readily seen in Figs. l, 2 `and 3, a ange is provided all around the oor slab but within the area of the platev 1'0. `This flange 14 extends upwardlyfor the total `depth of the slab and forms a box edge. The flange may consist of a strip of metal Welded or otherwise secured to the: steel plate or it may take the form oi one'leg of an angle-iron suitably secured to the plate. l Y. Y

A standard form of grating Ymay be .used for the upper portion of a iioor slab, but I prefer to use a gratingof a kind illustrated herein. One formA of this grating'consists of aplurality or" bent bars 15, Figs. 1 and2, which are Welded or otherwise secured to each other in a manner well-known. This upper grating, consisting ofv bars 15, is joined to the box ange 14 at such places as at 16, 17, which arepoints of contact between the iloor grating and the ange.

Before the floor grating'15 is positioned the inside steelconstruction of a floor slab must be completed.Y This construction preferably consists of bars running lengthwise of the floor slab and joining the floor grating. Bent bars such as 18, are preferable. They are not necessarily-joined to `-each other but they are welded to the plate 10 and the oor grating l5 and'thereby serve to unify the steel structure of the entire slab. It will be noted that these bars 18, as illustrated in Figs. l, 2 and 4, stand on edge and have their edges contacting with the plate 10.

It is apparent that by joining all of the bars 18 to the plate 10 and the grating 15 a steel skeleton is produced in'wh'ich `the steel is well distributed throughout. the slab. In fact, the

. dimensions of the grating bars, intermediate bars and plate may be sojproportioned as to locate the neutral .axis `practically on 'the center line of a slab, thus providing balance in section with maximum strength forany allowable weight per sla'b. While veach of such bars may run the length of a slab I preferto use several discontinuous bars in prolongation of each other, as illustrated. This arrangement reduces' the Weight of a ='slab rwithout saericing its strength. The skeleton construction is suiliciently strong to support all loads `which the slab may 'be Icalled upon to carry yand in fact it is possible to carry on bridge building operations, including the travel vof' vehicles thereover for the transportation of concrete, before any concrete or other lling vmaterial has been poured. Because of the uninterrupted character Vof a plate a most Y a bridge.

eiiicient tension member is present Awhere the greatest tensile forces act, and this fact, coupled with the presence of steel throughout the slab, creates a strong and rigid slab. f

In general floor slabs should be held down because of vibration to which they are subject. For this purpose they may be welded cr bolted to beams or, as shown inFigs. 3 and fi, each of the slabs may be clamped to a beam at its ends by means of clamps 2l and bolts 22. These clamps engage the flanges of the I-beam upon which the end of a slab rests.

After. the slabs have been laid in place all of the open area within the box lange 14 is illed with concrete or other filling material. This material serves as a road surface and may extend above the upper edges or just to the edges of the floor grating l5 and the upper edge of the box lange le. The space 23 between the box flanges of adjacent fioorfslabs may be filled with mastic or with material capable oi Ypermitting expansion between the various iloor slabs.

A,In

iorm ci iioor slab in which the plate 26 and the :oor grating 27 is similar to that of the oor slab just-described. However, the box iiange 273, extends around the outer edge oi the plate 26. The steel intermediate the plate and oor grating .27 consists oi bent bars 29 which run longitudinally from'one end to the other end of the slab. These bars are placed with their edges in vertical planes and rotated 90 from the position oi the intermediate bars shown in Fig. 1. These b 29 are likewisev welded to the plate 2G,v and the floor grating and produce a structure which is uniformly distributed with steel throughout. This floor slab also to be illed vwith some iilling material 30; The separation of the nllingA material intochannels is avoided. As may be readily seen from Figs. v and 7, the concrete below and above the intermediate bars '29 is directly associated with the concrete between the intermediate bars 29.

The `constructionoi the floor slab illustrated in Figs. 8 and 9 is of the same order as that of Fig. 5 except that the oor grating 31 is of a different design. This floor grating has straight members 32 between pairs of bent l Another manner in which I provide steel throughout the thickness of my floor slab is illustrated -in Figs. li) and 11. In a door slab of this construction the slab is vmade similar to that illustra-ted in Fig. 5 except that the intermediate bent members 35 run across the slab. This construction likewise hasthe advantage that avenues or long channels in the iilling are obviated. By the proper placing of the steel and the elimination of avenues inthe lling material the probability `of failure of the concretebecause of shear is eliminated. f

Another advantage of the construction of the present invention is that the lower yplate serves as a niould for receiving the lling material when itis being poured. The ll'ing material may readily distribute `itself throughout the area of the L slab and produce an integral mass of concrete. It has been found that the present oor slab may be relied von for resisting torsional strains which commonly occurrbetween stringers and beams onk Therefore in the design of the bridge jA ie ordinary cross bracing which is used to Vcounteract the effect of "torsional and weaving strains may be designed with a View oi utilizing the iioor slabs for assisting in cross-bracing. It sreadily understood that the main body or steel congs. 5, '5 and '7 I have illustrated anotherV struction of the licor Vslab may'be completed in the shop and later laid according to specifications and filled with concrete or other filling material for surfacing the slab. When an individual slab wears or if a defectshould develop,.such.a slab may be easily removed Without disturbing a large area of road way. y

It is apparent that different provisions may be made for joining the floor slabs to each other and for holding them in place next to 'each other. In Figs. 12 and 13 I have illustrated a tie-joint in which a plate 37 is bolted to the flanges 38 and 39 of adjacent slabs. This plate also has portions e0, Lil extending below the upper flange of an I-beam 42 in such a manner as to engage the Same.

1 do not wish to be limited to the shapes of the Various bars which may be used for it is ap-x parent that many other forms of gratings are satisfactory for serving Aas the upper portion of my door slab and that the bars intermediate the floor grating and plate may take many and varied forms. It is, however, my intension to produce a skeleton steel structure in which the steel is distributed throughout the thickness of the slab to such an extent as is necessary to counteract the longitudinal shear and diagonal shear ordinarily occuring within the interior of a slab or beam. The vertical shear existing at any point because of a concentrated load is carried by the steel of the slab, and the impact causedl by a travelling load as it progresses across different bars of the grating is transmitted to the steel plate through the intermediate bars which lie just beneath the upper grating. The concrete or other filling material is not called upon to withstand tension or to buttress heavy impact blows to which the grating is subjected when in use.

What I claim is:

l. As an article of manufacture, a floor slab frame comprising a series of bent bars joined together with the edges forming opposite sides of a grating, a plate forming the bottom of the frame, said plate being spaced from all members of said grating, a ange extending from said plate and enclosing the outer edge of said grating, bars intermediate the grating and plate, said intermediate bars extending in the same direction as the bent bars of the grating and having a width equal to the spacing between the grating and the plate, and welded joints between the intermediate bars and the grating and plate.

2. As an article of manufacture, a floor slab frame comprising a series of bent bars joined together with the edges forming opposite sides of a grating, a plate forming the bottom of the frame, said plate being spaced from all members of said grating, a flange extending from said plate and enclosing the outer edge of said grating, bars intermediate the grating and plate, each of said bars being joined to both the under side of the grating and the plate at several places along their lengths, the intermediate bars and the bent bars of said grating being associated in such a manner as toprovide steel reinforcing throughout the slab without dividing the volume within the box flange into disconnected spaces.

3. AS an article of manufacture, a floor slab frame comprising a series of bent bars joined together with the edges forming opposite sides of a grating, a plate forming the bottom of the frame, said plate being spaced from all members of said grating, a flange extending from said plate and enclosing the outer edge of said grating, and bars lintermediate the grating and plate and joined to each, said last named bars being distributed throughout substantially the entire area between the grating and the plate.

4. As an article of manufacture, a floor slab frame comprising a series of bent bars joined` to the grating and the other edge ,welded to the plate.

6. As an article of manufacture, a floor slab frame comprising a grating having longitudinal bars Ajoined together, said grating forming the upper structure of the frame, a plate spaced from said grating and formingV the lower structure of the frame, andrmeans separating the grating and plate and maintaining them in fixed relation to each other, said means comprising bars fastened to theunder surface of said grating and to the plate.

'7. The combination set forth in claim 6 in which the bars intermediate the grating and plate run lengthwise of the frame and are spaced at intervals across the frame.

S. The combination set forth in claim 6 in which the bars intermediate the grating and the plate run crosswise of the frame and are spaced at intervals from end to end of the frame.

9. As an article of manufacture, a floor slab v comprising a steel grating having bars with edges up and interstices between bars, a plate, a flange upstanding from said plate. and spaced from the edge of said plate, bent bars arranged be.- tween said grating and plate and Welded to each,

and filling material within the box formed byA said plate and upstanding flange, said filling material being unitary and extending into the interstices of said bent bars and grating.

10. As an article of manufacture, a floor sla frame comprising a steel plate for its lower surface, a grating in its upper portion, a flange bordering the grating and extending to the upper surface of the grating from the steel plate, and bars intermediate the grating and the steelplate, said bars running lengthwise of the frame and being welded toboth the grating and the plate.

11. As an article of manufacture, a floor slab frame comprising a lower plate, longitudinally extending bent bars having bends transverse to the bars, said bars resting upon and connected to said plate at the lower bends of said bars, and an upper grating spaced from said plate and connected to the upper bends of the aforesaid bent bars.

12. As an articlefof manufacture, a floor slab frame comprising a lower plate, longitudinally extending bent bars having bends transverse to the bars, said bars resting upon and connected to said plate at the lower bends of said bars, and an upper grating spaced from'said plate and connected tothe upper bends of the aforesaid bent bars, saidl upper grating comprising vmembers which extend longitudinally and in the same general direction as that in which the bent bars extend.

13. As an article of manufacture, a floor slab frame comprising a lower plate, an upper grating v section spaced therefrom and intermediate structure between said upper grating and said lower plate, said intermediate structure comprising a plurality of spaced bent bars having their lower bends connected tothe plate and their upper bends connected to the upper grating.

14. As an article of manufacture, a floor slab frame comprising a single metallic plate of substantial width and of a length approximately twice its width, a plurality of individual bent bars attached to the upper surface of said plate, said bars being independent of each other and spaced over substantially the entire area of the plate, and an upper grating section substantially coextensve with said plate, said grating section being attached to the bent bars which extend from the grating section to the plate and unite the same in a composite frame.

16. As an article of manufacture, a floor slab frame comprising a lower plate, an upper grating structure substantially coextensive with the lower plate and spaced therefrom, and intermediate structure comprising individual bars distributed throughout the area of said plate and standing on edge upon the surface of said plate, said bars having their lower edges welded t0 the plate and their upper edges welded to the grating structure.

HERBERT H. BUNKER.

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