US1733677A - Reenforced beam construction - Google Patents

Description

Filed Aug. 25, 1925 2 Sheets-Sheet l 0a. 29, 1929. T, 'H. E 1,733,677

REENFORCED BEAM CONSTRUCTION Filed Aug. 25, 1925 2 Sheets-Sheet 2 Patented Oct. 29, 1929 I ED STATES PAT THOMAS arise, or wrnsron-snnnmnonrn ,oARoLrn'A REENFORCEI) BEAM CONSTRUCTION 'Application filed August 25, 1925. Serial No. 52,416.

The invention will he described as applied to the construction of reenforced concrete floors. Although the end sections of the beams are subjected tonegative bending moments, it is customary to employ the same size and shape of tile throughout the length of the beams. Myinvention contemplates the use of difierently shaped tiles or blocks at those sections which are subjected to negative and to positive bending moments, respectively, the form foreach sectionbeing so chosen as to make the most economical use of the materials employed. Y

()bjects of the invention are to provide an improved reenforced beam construction which will have'a relatively high ratio of live to dead load, and one which may be made of reduced thickness further object or the invention is to provide a reenforced beam; construction which may be readily and accurately built withoutnecessitating the use of special block spacing apparatus and methods. More specifically, an object is to provide a floor beam having two types of hollow blocks for giving the desired change in the cross-section of thebeam and in the positioning of the reenforcing material. I

An embodiment of myinvention is illustrated in the accompanying drawings in which: I v 1 I Fig. 1 i a broken vertical section taken along the center line of a floor beam, the ocment not being shown; r v

Fig. 2 is a plan of a portion ofa floor, showing a completed beam and of two rows of tile assembled to receive the steel reenforcement and concrete;

Fig. 3 is a perspective view of a positive unit block; i

Fig. 4 is a perspective and negative unit block;

Figs. 5 and 6 are, respectively, perspective views of an intermediate and an end View of a positive negative unit;

ranged at the sections for a given loading. A

Fig. 7 is a broken vertical sectionon line 77 of Fig. 2; and I Fig. 8 is a view similar to Fig. trating blocks of a difierent size.

In the drawings, the'blocks which are, arof the bea'm subjected to positive and to negative bending moments 7 utane are designated by the character's Pand N, re-

the concrete being identified by spectively, I the character C and the reenforc ng'members by the character R. The general construction of floor'beams.embodying my invention is similar to known constructions in which the ends of the beams are rigid with the end support Sand in which it is usual to employ reeni orcing of such shape location'that two reenforcing rods lie'at the bottom of thecentral section of the'beam while I the end sections have a rodat the top and another at the bottom of the beam.

The positive units P, that is the'blocks p0 sitioned at the sections subjected topositive bending moment,are of approximately rectangularcross section having a top wall "10 which is parallel to the bottom wall 11, lateral flanges 12 preferably being provided as eX- tensions of the bottom wall for automatically spacing the rows of tile apart and'for closing the concrete receiving channel which is formed between adjacentrows. The side walls 13 extend downwardlyfromiand nor:- mal to the top wall for the greater part of the depth of the tile. and are'thenj contracted or recessed inwardly asat l4,-to provide an increased channel width'to take the two reenforcing members R. Lugs l5extend out wardly from opposite sides of each block to provide aseat forthe reenforcingmembers,

the upper recessed surface 16ofthe lug being spaced from theside wall and located above the level of the bottom'wall' 11' and flange 12. Integral longitudinal fillets at the upper inner corners of the block provide lower surfaces 17 forthe top wall, which surfaces lie substantially parallel to a plane OA passing through theneutraleaxis ofthe beam and the outer upper edge of the computed compression area of the beam, this feature of thepresent' invention being decation Ser. No. 67 9,195, filed Dec. 7, 1923.

The negative units N are of the same height as the positive units and are provided with bottom walls 18 and lateral flangeslt) which are ofthe same width as corresponding elements of the positive blocks. The side walls 20 of the negative blocks extend upwardly,

the bottom wall for the height of the' block, and

from and normal to greater part of the then are contracted inwardly by inclined walls 21 which are preferably joined to the top wall 22 by short vertical walls 23. Seats for the lower reenforcement are provided by lugs 24 which project from the blocks and have downwardly inclined upper surfaces which lie above the level of the spacing flanges. The blocks at the extreme ends of the beam carry lugs 24 which are of greater height than the lugs on the other negative units, whichlugs 2% provide a better bond by spacing the ends of the bars at a greater distance above the bottom of the concrete receiving channel. I V

The negative bending moment is maximum at'the extreme ends of the beams and the blocks N are provided with fillets 25 along their lower inner edges to assist in carryin the compression. Although the negative moments decrease towards the points of inflection I orefer to incor aorate the fillets in,

all of the negative blocks. The slope of the upper surface of the fillet 25 is such that it substantially coincides with the plane OA which passes through the neutral axis and the outer edge of the beam at the position ofmaximum negative bending moment.

The end blocks are provided with one end wall26 for preventing the entrance. of concrete into the blocks, the end wall being preferably indented from the end face of th block. The blocksof both sets are provided with a reenforcing rib 27 depending from the top wall ofthe blocks at their longitudinal center line and with a reenforcing flange 28 which projects inwardly from walls of the blocks. Theblocks maybe made molding operation, the flanges 28 and the reenforcement spacing lugs being made flush with oneiend of the blocks. s

The blocks of adjacent rows are preferably arranged tobreak joint longitudinally the beam, and the opposite walls at a point of inflection are formed by a positive and a negative unit, respectively. Considering one side of the beam, the positive unit blocks overlap one point of inflection and stop shortof'the other the arrangement being reversed at the opposite side of the beam.

The rows of blocks may be quickly and accurately placed on the usual falseworl; as they are automatically spaced by the lateral flanges. The two different types of bloclzs are used as determined by location of tie points of inflection .of the beam and the corby a rectnessof the placingof the blocks of the respective type may be checked by inspection, since the top walls of the two types are of different Width. With the rows properly laid, the steel bars are placed in the channels to rest upon the lugs which provide supports appropriate to the amount of steel atthe base of the beam. Each lug 16 of a positive unit forms a rod-receiving seat, and the lugs 24, 2a of the opposite walls cooperate to form 'a single V-shaped seat at the central plane of the beam.

While the configuration of the outer surface of the blocks is dependent primarily upon the amount of space required for the reenforcement, the inner surface of the blocks is determined by the maximum positive and negative bending moments. Tile of different sizes are not, therefore, since the inclinations of the planes OA, OA whichbound the compression areas vary with the depth of beam and maximum safe loading.

'Figs. 1 to 7 inclusive illustrate ten inch blocks, while in Fig. 8, six inch blocks are illustrated. From a comparison of Figs. 7 and 8, it will be seen that the slopes of the surfaces of the fillets of both the positive and the negative units "are smaller for the smaller size blocks. 7 V

The walls of the'blocks not only-act as the forms for the concrete of the beam but may be relied upon to take compression when a good grade of block is used and the blocks and concrete are placed with reasonable care. The central vertical portions of the walls are in longitudinal alignment-from end to end of the beam, but the walls are recessed or indented inwardly to provide adequate space for the reenforcement where the latter is double. Due to the change in shape of the blocks, the rod seats and the rods at the points of inflection, any error in the placing of the blocks, or in the shapefor location of the steel will be apparent when the reenforcing members are placed in'the channel.

In addition to these advantages, a floor embodying my invention is characterized by relatively low dead weight, which lessened weight in the'floor makes it possible to reduce the weight of the frame and footingof the buildings. As the dead weight is reduced, there isless material to buy, handle and place. For the same live load, the floor can be of lessthickness, or for a given depth of floor and quantity of steel, higher live loads may be carried. a

I claim:

1. In a reenforced concrete beam, two parallel rows of blocks, sald rows being spaced apart to provide a channel between the opposed side walls of the blocks, and concrete and metal reenforcing in said chamiel, the vertical central portion of the side walls of all of the blocks in the respective rowsbeing of identical design in substantial alignment from end to end of the beam, the side walls of the blocks at the middle of the beam being contracted inwardly at the bases thereof and the side walls of the blocks at the end section of said beam being contracted inwardly at the top thereof.

2. In a reenforced concrete beam, two parallel rows of blocks, said rows being spaced apart to provide a channel between the opposed side walls of the blocks, and concrete and metalreenforcing in said channel, each of said blocks having top and bottom walls which are parallel to each other and are spaced apart by the depth of the beam, and having side wall portions which are substantially normal to said top and bottom walls, the blocks at the ends of the beam having inwardly slopingwalls connecting the said side walls to the top walls thereof, and the blocks at the central section of the beam having inwardly sloping wall portions connecting the said side wall to the bottom walls thereof.

3. In a reenforced concrete beam having sections thereof subjected to positive and to negative bending moments respectively two parallel rows of hollow blocks, means at the bottom walls of said blocks for maintaining the said walls of the blocks of rows in spaced relation to provide a channel therebetween, metal reenforcing members in said channel and concrete surrounding said members and filling the channel between said rows, the side walls of the blocks at the sec- 1 tion subjected to a positive bending moment being recessed inwardly at the bottom thereof adjacent said reenforcing members, and the side walls of theblocks at the section subjected to a negative bending moment being contracted inwardly at the top thereof adjacent said reenforcing members.

4 In a reenforced concrete beam having the ends thereof rigidly secured to spaced supports, parallel rows of blocks having side walls spaced apart to provide a channel, lateral flanges extending from the bottoms of the opposed rows of blocks to close the bottom of said channel, the blocks at the central portion of said beam having inwardly contracted the side walls and the the beam having side inwardly at the top portions at the base of blocks at the ends of walls which contract portions thereof,

In a reenforced concrete beam having sections thereof subjected respectively to positive and to negative bending moments,

hollow blocks arranged in twoparallel rows for defining a channel for the reception of concrete and reenforcing members, the blocks at the section subjected to a positive bending moment having top walls of substantially the same width as the bottom walls, side walls extending downwardly from and normal to said top wall and inwardly inclined walls joining the said side walls to the bottom walls,

the opposed subjected to the :blocks atithe section of the beam subjected to negative bending moment having side walls extending upwardly from and normalto the bottom walls thereof and inwardly inclined wallsjoining said side ,wallsto the blocks having side walls recessed at the bot tom thereof, and the opposite side wall of the saidgchannel is formed by one'of the said blocks havinginwardly contracted side walls.

7. In a reeiiforcedconcrete end sections subject to negative ments anda centralsection subjected to positive bending moments, parallel rows of nega= tive and positive unit nel for the reception of reenforcing metal and concrete, the negativeunit blocks being locatediat the end sections and having side walls which provide beam having bending mo blocksdefining aichanan increased channel width at the top of the beam,'and the posi- I tive unit blocks being section and havingside wallswliich provide an increased channel nel at a point of inflection. 8. Inja reenforced beam subjected ing moments, respectively, parallel rows of blocks defining a concrete receiving channel of. enlarged width at the'top at the section subjected to negative bending moment and of enlargedwidthat the. bottom at the sec-;

bending moment,

the lugs at thesection subjected to positive bending moment having upper surfaces vided with concave recesses. j

9. In a reenforced, beam having sections subjected to negative and to positive bending moments, blocks defining of enlarged Width at the top at the section negative bending moment and of enlarged width at the bottom at the section subjected said blocks having laterally projecting lugs for positioning the reenforcing members and spacing the same'above' the bottom of the channel, the lugs formed on blocks at the section of negative bending moment having upper surfaces which propositive bending moment each having an up per surface provided with a recess at one side of the said vertical central plane. I

I having sections" to negative and to positive bend-j channel for posi-,i

respectively, parallel rows of a concrete receiving channel to positive bending moment,

slope downwardly to the central plane of the beam and the lugs formedon blocks at thesection subjected to located: at the central width at the bottom of said beam, a negative and a positive, unit" block forming the opposed walls of the chain 10. Ina reenforced concrete beam having sections subjected to negative bending moments at .the end portions thereof and .to 7 positive bending moments at a central portion thereof, parallel rows ofblocks providing a channel therebetween, and .reenforcement-supporting lugs on the blocks, the lugs on the opposed blocks of adjacent rows at beam sections subject to positive bending 1Q moments each having an upper recessed surface defining a complete seat for a reenforcing member, and the lugs on opposed blocks atbeamsections subject to negative bending members cooperating to define a single 15 seat for receiving a reenforcing me'mbensai-d last mentioned lugs each having a downwardly sloping upper surface.

' 11; The invention as claimed in claim 10,

wherein the lugs on the extreme end blocks 20 are of greater height than those of the intermediate blocks. V 12. The inventionas claimed in claim 5, wherein the lower surface of the top wall of V the blocks at the section sub'jectedto posi- 5 tive bending moment slopes downwardly from the center of the blockto the side walls thereof, said surface being substantially parallel with a plane passing through the computed neutral axis of the beam and the outer- 39 upper edge of the computed compression area. 7

13. The invention as claimed in claim 5, wherein the upper surface at the outer edge of the bottom wall slopes upwardly towards the side walls, said surface being substantially parallel with a plane passing through the computed neutral axis of the beam and the lower outer edge of the computed compression area at the position of maximum nega- FlQ? tive bending moment. 7

, In testimony whereof, I afiix my signature.

THOMAS H. TISE.

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