US1050477A

US1050477A - Reinforced-concrete floor construction.

Info

Publication number: US1050477A
Application number: US62107211A
Authority: US
Inventors: Alfred E Lindau
Original assignee: CORRUGATED BAR Co
Current assignee: CORRUGATED BAR Co
Priority date: 1911-04-14
Filing date: 1911-04-14
Publication date: 1913-01-14
Anticipated expiration: 1930-01-14

Description

A. E. LINDAU.

REINPOROEO OONORETE FLOOR OONSTROOTION. APPLICATION FILED APR. 14, 1911.` wglgf?. Patented Jan. 14, 1913.

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A. E. mmm. REINFOROBD CONCRETE FLOOR CONSTRUCTION.

APCPLIUATION FILED APR. 14, 1911.

Patented Jan. 14, 1913.

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A. E. LINDAU.

REINFOROBD CONCRETE FLOOR CONSTRUCTION. APPLIUATION FILED 111211.14, 1911i 1,050,477. Patented Jan. 14,1913.

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ALIBED E. 'LINDA-U, ST. LOUIS, MISSOURI, ASSIGNOB T0 CORRUGATED BAB COMPANY, OF ST. LOUIS, MISSOURI, A -COZR'POIBA'IIOll' 0F MISSOURI.

BEINFORCED-CONCRETE FLOOR CONSTRUCTION.

Specioation of Letters Patent. Application led April 14, 14911. v Serial No. 621,072.

To all whom t may concerne Y Be. it known that LALFRED E. LINDAU, a and a resident of the city of St. Louis and State of Missouri, have invented a new and useful Improvement in Reinforced-Concrete Floor Construction, of which the following 1s a specification.A

My invent-ion relates to a new system of arrangement of reinforcing rods in concrete floors of the type in which a flat slab of concrete of substantially uniformthickness is supported directly upon the column caps, without the .intervention of glrders.

Investigation has shown that the dlstribution of tension stresses in girderless reinforced concrete doors is such that present methods of reinforcement do not adequately cover the, tension regions. Particularlyis this true in the upper surface of floor slabs .tersecting'- the co umns, or what may be temieds longthe edges of the iioor panel. Itis also necessary .tect the tension re adjacent to the co to more' carefully pro- `on immediately over and umns. Heretofore it has been a general practice to place layers of reinforcin bars 1n the bottom central region of the s ab, said bars extending from the :bottom central region of the slab in several .directions up into, or near the upper surface of the slab at its edges, and in some cases to add to these slab bars one or more layers of additional bars, usually straight, ar-

ran in the top of the slab. The result isiirst of all,.to pile u so many layers of bars'in-the topof, the s ab at its edges as to bring the -center of gravity of the reinforcement'at these points nearer the neutral axis ofthe slab, making this reinforcement proportionatel less effective, and in the second place t e bent upbars usually dip down from the top to the bottom surface of the slab so near the columns as to leave a large portion of the tension region in the top of the slab above the columns unpro# tected. I have devised a system or method of reinforcing door slabs of this type, that is, that in whlch girders across the columns are dispensed with, which will more adequately take care of the stresses and with a less amount of metal reinforcement, than is possible with the systems in general use.

My improvements consist in placing the bar's parallel to the rows of columns or view,

edges of the panels and crossing the anels in two directions only, at right ang es to each other, and in the detail arrangement of reinforcement as is shown in the drawings accompanying this specification, and forming a part thereof.

My improvements are not restricted to girderless concrete floors but are applicable to the arrangement of the reinforcing rods in tile-concrete or composite doors, and floors divided into sections or panels by girders connecting the columns.

Patented Jan. 14,1913.

In the drawings, 1n which like parts are i designated by like characters .wherever they occur,.-F1gure 1- is a plan view .of the rcinforcement in a center panel of a at slab of an adjacent panel 5 thereinforcement 1n the top of the slab being shown in full lines and that in bottom of the slab in dotted lines; Fig. 2 is a similar view of a .wall

panel of a flat slab floor embodying my in- 4floor embodying my invention, showing part v vention;. Fig. 3 is a transverse section through a center panel along the line 3 3 in Fig. 1; Fig. 4 is a transverse ,sect-ion through a wall panel along the line 4-4 in Fig. 2;v and Fig. 5 is a diagrammatic view olf he reinforcement of a portion of the door s a Referring to Fig. 1 of the drawin s the arrangement of bars in-a typical pane of a flat slab floor supported on y'columns is shown, as though all the concrete in the slab above the upper layers of bars were removed, thus exposing these layers of bars in full while the layers of bars in the lower art of the slab are indicated by dotted mes.

The reinforce consists of two series of principal tension bars 11, 12, arranged4 at right angles to each other parallel to the rowsof columns. These bars for approximately 4the middle three-fifths of the span are placed in the lower portion of the slab and are bent up at the ends to lie in the top port-ion thereof, the end portions of the bars extending overinto the marginal portions of the adjacent panels, and overlapping the end port-ions of the

similar bars

19, 20 in the adjacent panels. Alternating 'with ythese principal tension bars and grouped ,in tension across the middle part oit' the span, and in compression at their ends. rllhe bars 18, la terminate near the margins of each panel, where they aline with similar bars 5,22 in adjacent panels.

'Each group of bars is width with the width of the the rows of columns and t provide all the rein bottom of the coextensive in anels between etwo oups orce necessary in the slab, as whatever the direction ofthe stress in the slab at any given point, it may be resolved into two component stresses, parallel with the reinforcing bars. As the stresses at right angles to the lines connecting adjacent .columns are found to be less in flat slab loors in the regions remote from the columns than in the regions near the columns, the lateral spacing of theV th bars lin each group may be graduated, and

the intervals .between the bars `may be greater toward the center of the span without impairing the strength of the floor.

Heretofore fiat slab floors have been constructed having reinforcing rods crossing the panels diagonally from corner to corner or radiating from the columns through the slab in every direction. Such arrangements of reinforcin rods do not reinforce the top portions of t e licor slab in the regions bea() .tween adjacent columns against tension stresses transverse to the straight lines connecting said columns. By arranging the reinforcing bars in groups parallel to of some of the bars of each group to lie in the top portion of the slab in the marginal -regions of the panels in directions `perpendicular to the respective sides thereof, vthereby these bent up bars assist in taking care of the tension stresses in the top oit' the slab in the regions between the columns. Moreover, in flat slab floors the maximum stress in the slab under ordinary conditions of distribution of the load on the Hoor is over the columns. Heretofore belts of`reinforcingv bars have been placed crossing each the' large tensiony stresses This piling up ,of layers of metal over the columns results in lowering the center of gravity of the reinforce and raising the position of the neutral axis oi? the slab, thereby greatly increasing the compression 5; stresses in the lower portion of the slab in Vthe regions near the columns.

By placing straight bars''in the lower portion of the slab in t-he marginal regions of the panels and near the columns the so effect of the bent up bars in changing the position of the neutral axis of the slab in these regions is partly equalized, and at the same time the compression stresses are distributed between the concrete and straight bars in such a way as to stiften the slab at 'and compression, in the slab.

at these points.

incoar? the columnsl and reduce the dedection of the slab between the columns, thus changn ing the distribution of stresses, both tension Also, by arranging the bars in two directions only, the reinforcement over the supports above and below the neutral axis of the Vslab will be in two layers instead of tour or more,V giving the reinforcement a y greater lever arm for resisting the bending moment at the supports, as the center of gravity of the reinforcement is farther from the neutral axis of the slab.

Short supplementary bars 17, 18, are

placed in the upper region of the slabs over and between adjacent columns, these bars being perpendicular to the lines connecting e columns and disposed at intervals in the planes of the bent up ends of the tension bars extending in the same spacing apart of these bars is increased toward the middle ofthe span, for the same reason as .the spacing apart of the bent up slab bars already referred to. 'llh'e bent up slab bars and the supplementary bars together furnish a sufiicient amount of top reinforcement in this region.

The net work or grillage of top bars may be held in place by main bars l5, 16, two for each row of columns, disposed in the top er, portion of the slabparallel to the rows of columns and wired to vertical reinforcing bars in they columns, which latter are not shown in the drawings. By bending down the ends of the alternate top supplementary bars over the columns, additional shear prcvision can be obtained lwherever this may' be desirable. By placing these supplementary straight or bent bars between the main tension bars in the 'upper region or' the slab over and between the'columns at grada" atedy intervals for the greater part of' they span, not only is the whole regiony of tension in the top of the slab between the columns reinforced, but also the bars are so disposed as to be properly proportioned to the varying amount of the tensional stresses at various distances from the columns.-

The concrete slab'is increased in thickness over the column for a distance varying from one-third to one-quarter of 'the span. This is done to decrease the shearing stress' adja- Y cent to the column, and to decrease the' com pressive stress in the concrete on the under side of the slab, and results in 'considerable economy of material, as Va twenty-five per cent.y increase in thickness over this area requires no more material than an increase in thickness over the total area of the slab of not more than three or four per cent., whereas the increase in strength of the slab as a whole is over twenty-tive per cent.. by reason of this increased thickness of the slab near t-he columns.

ilo

-ligz 2 shows my improved arrangement l() l direction.; The 35 v one series being arranged to ,extend parallel l tom region of`the the top region-of the sla appliedto a floor slab having one'edge supported in a wall, and differs from the arrangement shown in Fig. 1 in omitting the sup lementary tension rods and some of the com ined tension and compression rods along the edge of the slab supported in the wall.l

While my system or arrangement of metal reinforce is particularly adapted to floor panels supported atl their corners, it is evident that it is not restricted thereto, but may be applied to iioor anels supported on walls at one or more e ges. 4

Having described my improved floor system what I desire to claim and secure by Letters Patent is as follows:

1. A monolithic floor-slab resting on rows of 'columns intermediate its margins and consisting of concrete and series of reinforcing rods positioned therein, the rods of with a row of ,columns and disposed lat graduated intervals throughout the width of said slab,v and the rods of another series being arranged at right anglesto the rods of said first mentioned series and disposed at graduated intervals throughout the length of said slab, the rods of both said series spanning the panels between said rows of columns and being bent. to extend through the bottom region of the slab atA the middle portions of the panels and through the top region of the slab at the margins of the panels.

2. In a reinforced concrete floor, a floor panel having reinforcing rods arranged parallel with the respective edges thereof andextending beyond-said. edges into the adjacentlpanels respectively, said rods intersect ingl at right angles toeachother throughout the entire area ofthe panel, and supplementary reinforcing rodsarranged around .the edges of the panel and at right angles thereto, said supplementary rods being in the same horizontal plane with the adjacent portions of the first mentionedrods extending in the same direction, there being not more than two layers of vrods on the same side of the neutral plane of the panel at any one point.

3. In a reinforced'concrete floor construe tion consisting of a girderless flat plate slab of concrete resting on rows o-f columns dividing it into panels along the center lines of said rows, reinforcing bars embedded in said slab arranged in groups of parallel rods, there being two groups in each panel, said groups crossing each other and the bars in each group being parallel to a side of the panel and bein spaced apart at intervals from side to si e thereof, the bars of each group being all in the same lane in the botanel `t roughou't their middle portions, an su plementary bars in crossing the edges y of said panel and extending into the adjacent anels, and rods in the to the s ab aroundthe margins 0 upon which the supplementary bars rest.

4. In a reinforced-concrete floor construction consist-ing of a slab of on rows of columns dividing it into along the center lines of -said rows, reinforcing bars embedded in said slab arranged in groups of parallel. bars, there being two 'groups in each panel, said groups crossing eachother, and the bars in'each grou being parallel to a side of the anelfand eing spaced apart at intervals, ing and being greaterat the middle of the panel than toward the margins,the bars of each group being all in the same plane in the bottom region of' the panelacrossV its middle ortion, some of said bars having their en s offset `upwardly into a horizontal plane, and supplementary bars inthe topl region of the slab crossing the edges of said panel and extending into the adjacent panels, said supplementary bars being in the saine planes with the ends of main bars ex-. tending in the same direction therewith.

5. In a reinforced concrete structure having a pluralit yof panels supported at the vcorners thereo ,a system of reinforcing rods crossing a panel lin a direction at rightV angles to the line connecting the points of support at one edge thereof, and extending. into the adjacent panels, a second system of reinforcing rods crossing the panel at right angles to the first mentioned system of rods, and extending into the adjacent'panels, and

bars alternating with these systems of rods -andterminating shortof the edges of the panel.

6. A reinforced ,concrete Hoor panel Vhav-r -ing a pluralityof systems ofparallel ref' inforcing rods arranged to cross each other in adjacent planes throughout the length region of' the panels concrete restingpanelsl said spacingvaryand breadth of 'said'paneh each of said systems comprising straight rods and bent rods .extending inthe same direction across the panel, the middle portions of' said rods ex-y tending' in the same directionv being ar ranged in the same horizontal plane wyherefv by not 4more than two horizontal layersof rods lie in proximity to each other.

7. A reinforced 'concrete flooring clom-l prising substantially rectangular vpanels havin series of reinforcing rods arrange at rig t angles to each other acrossv the length and breadth of a panel parallel with the respective edges.' thereof, .the ends Vof the rods of each series lying inl the saine plane and extendin the ends of thevrods of eachv series andv parallel' thereto respectively, said-fliers beinto .the V-adjacent. panels, .and barsI positioned inthe plane .of

i'ngarranged in the' marginalre'gion of the v panels and crossing the same at right angles to their meeting edges;

' 20 into panels defined by -40 and the other` I columns in 8.' A reinforced concrete flooring comprising substantially rectan lar panels having Vseries of reinforcing ro s arranged at right angles to each other across the length and ibreadth of a panel parallel with the respective edges thereof, the ends'of the rods of each series lying in the same plane and extending into the adjacent panels, andv bars plane of the ends ofpositioned in the the rods of each series and thereto respectively, the bars and rods in the regions adjacent the respective edges of p the panels with which they are parallel being spaced nearer together than ranged across the middle portion of the panels.

9. The combination of columns and a monolithic reinforced concrete floor slab extending across said columns and divided lines passing through the centers of said columns, ,the reinforcement of each panel comprising a series of rods extending longitudinally of said' panel and into thepanels contiguous t the ends '25 of said first mentioned panel, and a separate series of rods extending transversely of said first mentioned panel and. into thepanels contiguous to the sides of said rst men tioned panel, the longitudinally extending rods being spaced apart throughout the entire width lof the panel, and the transversely extending rods being' s aced apart throughout the entire length or thel anel, all of said rods being in the lower portion of parallel the slab in the middle region of the panel and some of the rods of each series having their end' portions offset and lying in the upper part of the slab in the regions adjacent to .the margins ofthe respective lpanels rods of each series being straight, whereby said reinforced door slab simulates the action of a homogeneous flat' plate. 4

l0. A reinforced concrete uniform thickness resting o-n columns arranged in parallel rows in two directions approximately at right angles to each other, the lines passing through the centers of the each direction dividing the floor 5,0 into panels, groups of reinforcing kbars in said slab lying in two directions parallel to the sides of the panels, said bars being spaced apart at graduated intervals close-r together at the margins of the panels than at their middles, all of the rods of each group being in the lower portion of the slab in the middle region of the panel and some of said-rods of each group having their end portions offset and lying in the upper part of the slab in the regions across the margins of the respective panels, and the other bars of each group being straight, whereby said reinforced floor slab simulates the action of a homogeneous fiat 65. plate.

those ar slab, spaced parallel,

floorv slab of adjacent to and insonne ll. A reinforced concrete door slab rest'- ing on columns arranged in parallel rows in two directions angles to each other, the floor slab being of uniform thickness except for the areas adjacent to the columns, where the thickness is increased, reinforcing bars extendin crosswise throughoutthe ength; andv breadt of said slab in two of columns, said `bars being spaced closertogether 'near the rows of columns than across the middlesv thereby, some of the-'bars in each series being straight, bent bars between saidstraight' bars, said bent bars and straight bars in each series being in the same plane inthe lower region' of the'slab at theiry middles,

approximately at right series parallel to the rows l" of the panels dened the ends of` the bent bars in each series extending across the margins of lsaid panels and being 1n a plane-above' said first mentioned plane whereby said reinforced floor slab simulates the action of a homogeneous flat plate.

12. A reinforcddeconcrete floor slab resting on columns arranged 'in parallel rows in two directions, approximately at right angles to each other, said slab being of uniform thickness except for the areas adja-V cent to the columns, said areas being of greater thickness than the remainder of the reinforcing bars in said slab extendinggin two directions par'- allel to the rows of columns, the spacing apart of the bars beinga minimum near the rows of columns, lsupplemental bars arranged in the slab in the form of grillage in the areas adjacent to the' columns and- 'means for nsupporting' said supplemental bars in the top region of the slab whereby said reinforced licor slab simulates the action of a homogeneous flat plate. l"

13. A reinforced concrete door slab of uniform thickness resting on columns arranged iny parallel rows in two directions, the lines plassing through the centers of the columns in each direction dividing the floor into panels,v groups' of parallel reinforcing bars arranged crosswise to each other, the bars in each of said groups being spaced apart yfrom edge to edge of the panels, the spacing of the bars being a maximum in the middles of the panels and a minimum at the margins of the panels, said groups comprising bent bars passing from below the neutral plane at the middles of the panels to above'it across the vmargins thereof and straight bars in the same plane with the middle portions of the bent bars whereby said reinforced floor slab simulates the ac tion of a homogeneous flat plate.

14. A reinforced concrete floor slab resting on columns arranged in rows at' right angles to each other, saidslab being of uni-A form thickness except for the areas adjacent to the columns, the thickness of said slab adjacent to the columns being greater than that of the remainder of the slab', reinforcing bars crossing each other at right angles throughout the slab, said bars being parallelto the 4rows of columns and spaced apart at graduated intervals, the spacing diminishing from the middles of the panels toward the rows of columns in each direction, said bars passing from below the neutral plane of the slab at the middles of the panels to above it across the regions adjacent to the lines connecting the rows of columns whereby said reinforced floor slab simulates the action of a homogeneous iiat plate.

15. A reinforced concrete floor slab of uniform thickness resting" on columns ar.

ranged in intersecting parallel rows, the lines passing through the centers of the columns of the rows in each direction dividing the oor into panels, main reinforcing bars parallel to the sides of said panels passing from below the neutral plane at the middles of the panels to above it across the margins thereof and intersecting throughout the slab, said bars being closer together at the margins of the panels than at the middles thereof, supplemental` bars in the form of grillage placed in the slab in the areas over and adjacent to said columns, said supplemental bars being in the same planes asthe main bars adjacent thereto which extend in the same directionwhereby said reinforced floor slab simulates the action of a homogeneous flat plate.

Signed at St. Louis, Missouri, this 11th day of April, 1911..

A. E. LINDAU. Witnesses:

A. M. HoLooMBE, M. A. SHELTON.

copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C.