US 2844024 A
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July 22, 1958 J. L. MODONALD 2,844,024
COMBINATION PRERORMEO AND cAsT-lN-SITU f REINFORCED FLOORING STRUCTURE Filed Oct. 21, 1954 2 vSheets-Sheel'. 1
l Z0 RAN J. L. McDoNALD 2,844,024 COMBINATION PREFORMED AND CAST-IN-SITU REINFORCED FLOORING STRUCTURE Filed Oct. 2l, 1954 2 Sheets-Sheet 2 July 22, 195s zo?? lE/c je United j, States Patent 2,844,024 COMBINATION `PREFORMED AND CAST-IN-SITU REINFORCED FLGORING vSTRUCTURE James Leonard McDonald,lNew York, N. Y. Application October 21, 1954, Serial No. 463,769 1 Claim. (Cl. 72-66) This invention relates to improvements in the method and construction of reinforced concrete roadways and building floors or roofs, and more particularly is directed to the use of easily handled truss joists or knockdown parts thereof that can be readily assembled in situ for positioning prefabricated concrete slab units to incorporate same in reinforced concrete roadway or said building constructions entirely eliminating wooden or other forms usually required thereby saving expensive labor and carpentry work, reducing insurance costs on the buiding job, and requiring a minimum of material.
Among the objects of the invention is to generally improve constructions of the character described and the method of installation, which construction shall comprise few and simple parts that are readily assembled from prefabricated or partly fabricated members requiring ready and easy association all incorporated into the structure being built, which shall eliminate the necessity of utilizing forms for molding a desired reinforced concrete structure, which shall save labor and time as compared with the best known present practice in accomplishing like results, which method shall reduce waste of material on the job to a minimum and employ the used material to their utmost utility, and which shall be practical and efficient to a high degree in use in small as well as large scale construction work.
Other objects of the invention will in part be obvious and in part hereinafter pointed out.
The invention accordingly comprises the steps of the manufacturing method and features of construction, combination of elements and arrangement of parts which will be exemplified in the method and construction hereinafter disclosed, the scope of the application of which will be indicated in the claim following.
In the accompanying drawing in which an illustrative embodiment of the invention is shown:
Figs. l and 2 are top plan and side elevational views, respectively, of a fragmentary portion of a bridge roadway spanning spaced apart stringers constructed to embody the invention showing improved triangular truss joists each having three parallel aligning bars interconnected by struts, said joists supporting precast concrete slab uniform units interfitted to form a bottom side or downfacing finished wall of the structure before a roadway concrete slab is molded thereon to encase the joists before reinforcing rods or wire have been installed where found desirable, said roadway slab being shown in Fig. 2 by dot and dash lines.
Fig. 3 is an enlarged cross-sectional view taken on line 3-3 in Fig. l showing fragmentary portions of adjoining precast slab units interlocked by a plate strap or saddle.
Fig. 4 is an enlarged perspective view of the plate strap or saddle shown in Figs. 1, 2 and 3.
Fig. 5 is a perspective view of one of the precast slab units showing the upfacing side to which is molded the required roadway slab and from which upstands suspension hook members and interlocking studs.
Fig. 6 is an enlarged fragmentary cross-sectional view taken on line 6 6 in Fig. 2 showing the interiitting of the adjoining slab units securing the latter to the joist bars against relative movement and in additio-n reinforc-4 ing rods for the roadway slab portion.
Fig. 7 is an enlarged fragmentary cross-sectional view like Fig. 6 but showing the method of assembling the slab units into rigid interfltted position shown in Fig. 6. Fig. S is a cross-sectional view taken on line 8-8 in Fig. 6 showing in plan the rigid intertting of the adjoining slab units, and e Fig. 9 is a fragmentary cross-sectional kview of one end of the completed bridge roadway construction embodying the invention which has the upper roadway slab laid to unite and bond with embedded truss joists, reinforcing rods and underlying slab units to a predetermined over-all thickness yet requiring no molding forms.
An example of a construction embodying the invention is shown in Figs. l, 2 and 9 as bridge roadway 2b spanning spaced apart horizontally disposed stringers 20a and 2Gb, said roadway 20 being of predetermined over-all thickness including reinforcing triangular truss joists 21 incorporated in an upper cast roadway slab portion 20c laid to unite with and be bonded to underlying precast slab units 22 yet requiring no molding forms in the improved manner hereinafter more fully described.
Said stringers 20a and 2tlb on which said roadway 20 is carried may be of any suitable construction, such as,
parallelly extending steel l-beams on which opposite ends .21m and 2lb of truss joists 21, respectively, are supported. Each truss joist 21 may be formed as shown in Figs. 1, 2, 6, 7, 8 and 9 of three horizontally extending spaced apart bars 2te, 2id and 21e rigidly interconnected by suitably shaped struts Zlf and 21g and cross-tie braces 21h. As here shown, each of said struts 21j and 21g and cross braces 21h may be formed of reinforcing rod stock bent and welded as at joints 21j, into a sawtooth configuration, each of said struts being formed extending between a triangular formation provided by the disposition of said three bars 21e, 21d and 21e which, with said tie braces 21h, provide a rigid relatively light Weight framework. Struts 21f and 21g may have a half length portion of each sawtooth configuration thereof oppositely disposed as a symmetrical load carrying arrangement, said halves extending in relatively opposite directions from interposed stretcher braces 21k and 21m. Thus, if desired, said halves o-f struts 21]c and 21g, cross tie braces 21h and stretcher braces 21k and 21m as well as bars 21C, 21d and 21e may be furnish-ed on the job prefabricated to size and shape or knocked down in easily handled sections or parts and assembled as required by simply Welding, as is clear'from Figs. l, 2, 6, 7, 8 and 9.
Underlying precast slab units 22 may each be rectangularly shaped and made of concrete suitably reinforced as at 22j by wire mesh or expanded sheet metal, said units 22 having a smooth, even or otherwise nished under or downfacing surface 22a and a rough bonding top or upfacing surface 22]?. For each unit 22 there is provided spaced apart connector links 22C, as here shown, each being formed with one anchored end portion 22d embedded in said slab unit 22, opposite end hook portions 22e of each link 22C being positioned to upstand from said upfacing surface 22b along opposite border edges 22g and 22h of said unit 22.
As is clear from Figs. 2, 3 and 5, edge sides 22k, 22m, 22u and 22p of each slab unit 22 may be formed with mating tongue or ridge and groove abutting surfaces, respectively, to provide alignment of said under surfaces 22a of each unit 22 with that adjoining and to assure inconspicious tight joints therebetween.
There may also be provided to upstand from said upfacing surface 22b, spaced apart headed studs 22g arranged along opposite border edges 22r and 22s of each unit 22 and a plate strap orsaddle 222 may be fitted to engage and interlock each pair of studs 22g for interlocking adjoining slab units 22 to retain same against alignment displacement, as shown in Figs. l yto 4.
In the improved construction here shown,"and as is clear from Figs. 1 to 6, truss joists 21 may lbe spaced apart a distance equal to the length of each unit 22, as for example, when the latter is prefabricated to form a square slabthree feet by.,three feet, the distance between truss joist bars 21c.is .a .corresponding distance of three feet, with contacting .border edges 22g and 22h positioned under cross tie braces 21h midway between truss joist bars 21d and ;21e. When so assembled, linkv end hook portions A22e of .adjoining units 22.wil1.be positioned to engage said bars 21d and 21e, as shownin Figs. 6 and 8.
.From the .abovedescription and the drawing, the utility of the invention will. now 'be apparent.
After erecting. bridge I-beam stringers a and 20]: spaced apart for carrying roadway20, thetruss joists 21 areassembled-and made of sufficient length to span the aligned .distance between said stringers 2da and 20!) for resting thereonin spaced apart parallel relation, as is clear from Figs. 1 and2.
lSlab units 22 may then be mounted on horizontally `extending bars 21d and 21e by engaging link end hook portions 22e of said units 22 in rows with the groove and tongue. edge sides thereofiitted together to provide a cornpletelyiinished under portion for the yet unfinished bridge roadway 20. To retain said units 22 rigidly in assembly,
partially bent end `.22e of said link 22C may be fully bent.
from..the ,dotted lineto the full line positions shown in Figs. .6 and 7. -If desired, relative movement between adjoining units 22 may be prevented. by applying plate straps or saddles22t to interlock with pairs of studs 22g, .as is clear from Figs. 1 to 4.
Suitablefreinforcing rods.20d and 20e for constructing 'the roadwayslab .portion 20c may be installed and secured horizontally extending and parallelly aligned adjacent joist-upper Ibar 21C and also adjacent lower pair of joistbars 21d andglle, respectively, as shown in Figs. 6 and 9.
Thereafter,. upper roadway concrete slab 20c is laid Iby pouring the. same to unite and bond with slab units 22 .and ito embed truss joists 21 and reinforcing. rods 20d .and20e to a;predetermined.overall thickness yet requiring none of .the'..usual molding forms, the Prefabricated bond the plate strap or saddle 221? into roadway slab portion 20c, said strap 221? may be formed with an upstanding ledge 22u having a through-opening 22u for engaging reinforcing rods 20]c which are embedded in said sla'b portion 20c, as is clear from Figs. 1, 3 and 4.
It will thus be seen -that there is provided an improved roadway and -building reinforced concrete construction and method thereforin .whichvthe several objects of the slab units;22` serving. the 'function of such molding forms,
as is'clear f romJFigs. 1, 2, 6,7, 8 and 9.
Since in theabove/described operations, roadway slab 20c, truss. joists .21, reinforcingrods 20d and 20e and vunits .22 become -united andfbondedtogether into a single one-piece roadway-reinforced structure 20, the latter is recognizedvand considered in calculating the maximum stresses andustrains forsaid structure 20 making use of all the materials aforementioned either prefabricated or .formed and assembled on the job.
Theimproved method is thus seen to utilize prefabricated=reinforced concrete slab units 20 described above bonded to roadway slab portion 20c which incorporates truss joists 21 and may comprise the steps of first erecting the truss joists 21 andsupporting same on beam stringers y20a andr20b-'in spaced apart horizontally disposed relation to correspond to adimensional size of said units 22, and next interlockingly engaging said units 22 in an alignment relation supported under said truss joists 21 with the unit bonding surfaces 22b upfacing to-war-d said truss joists 21 and with said finished surfaces 22a downfacing `to .provide an exposed exterior side of said structure. Then, if desired, interlockingly engaging pairs of Istuds 22g with saddle plate strap 221 and securingly installing reinforcing rods L20d and 20e adjacent joist upper bars` 21C and .lower pair of joist bars 21d and 21e, respectively. vNext llayingbatches of concretel to embed -the truss joistsr 21 and said rods 20d and 20e, covering the unit npfacing bonding surface 22b to a predetermined depth-to for-m when hardened a complete unified bridge roadway -structure:20 with said unit downfacing surface forming a iirmilied'fexteriorside for saidstructure 20.
.I It should beynotedthat inorder to .more positively invention are achieved and which are well adapted to meet the conditions of practical use.
As various other possible embodiments of the invention might be made of the .above invention, andas various changes in the Vembodiments above set, f orthumight be made, it is to-.bepnderstood that all matters herein set forth or shown in the accompanying. drawings `anddescribed in the. speciiication are tovbe interpreted as illustrative and not in alimiting sense.
Having thus. described .my invention, I claim yas new and desire to. secure by .Letters Patent:
.A reinforced concretestructure of the character described supported; on a plurality of spaced apart horizontalstringers, said concrete structure comprising prefabricated concrete slab units of uniform shape and size each having an up'facing bondingsurface opposite a downfacing finished surface, a poured concrete slab portion of predetermined thickness incorporated as a unitary structure upon said'slabr units, reinforcing means for said concrete structure .extending throughsaid poured concrete slab portion including a plurality of truss joists each horizontally disposed and including three spaced apart elongated bars, a pair of .struts and cross tie braces interconnecting said bars to form a .rigid structure of triangular cross-sectional contour, a pair of said elongated bars having opposite ends .thereof resting on4 said stringers spanning the distance therebetween, means'for interlockingly suspending each of said units in alignment beneath said truss joists as `a horizontally disposed supporting surface for the poured concrete slab portion prior to pouring and as a linishedexteriorY undersurface for said concrete structure, said suspending means including spaced apart links upstanding from said bonding surface of each of said units adjacent opposite rim border portions thereof, one end portion of each link being anchored to the slab beneath said bonding surface and the other end portion of each link being hook-shaped and engagingoney of the pair of said elongated bars, each ofrsaid concrete slab units having edge sides extending betweensaid upfacing and downfacing surfaces formed with complementary ridge andgroove aligning portions for said interlocking therebetween, spaced apart headed studs upstanding from said bonding surface of each of said sla-b units adjacent other opposite rim-border portions, and saddle plate straps interlocking pairs of said studs on adjoining units to rigidify the assembly, each of said saddle plate straps having an upstanding ledge formed with a through-opening engaging a reinforcing rod extending into said poured concreteslab portion for a more positive bonding of said prefabricated slab units to the poured concrete slab portion.
References Cited in the le of'this patent UNITED STATES PATENTS 739,646 Carter Sept. 22, 1903 809,090 Caine Ian. 2, 1906 1,065,119 Early June 17, 1913 1,778,315 Ferguson Oct. 14, 1930 1,986,171 Wilson Jan. l, 1935 2,230,349 Eaton et al. Feb. 4, 1941 2,271,584. Felloin Feb. 3, ,1942 2,465,074 Edge Mar. 22, 1949 FOREIGN- PATENTS 274,291 Great Britain July 21, 1927 822,154, Germany Nov. .22, 1951