US1241945A - Method and means for forming concrete structural members. - Google Patents

Description

M. FLETCHER.

METHOD AND- MEANS FOR FORMING cowcnm STRUCTURAL MEMBERS APPLICATION FILED MAY 23' I917, 1,241,945;- Patented Oct. 2,1917.

7 2 SHEET$-SHEET I.

ATTOR/VES #JMK M. FLETCHER.

METHOD AND MEANS FOR FORMING CONCRETE STRUCTURAL MEMBERS.

APPLICATION FILED MAY 28. um.

1,241,945. Patented 00 5. 2,1917.

2 SHEETS-SHEET 2.

WITNESS MATTHEWS nnnrcnnit, or InDiAnAroiJis," nvDiAnA."

- MnrrHon AND ivrnANsroR FORMING e weaemsme wemn masses.

. hpplication filed May 28,1917. SerialNo. 171,540.fi

To all whom it may concern:

a citizen of the United;States,.-residing; at

Indianapolis,. Marion county, andystate of- Indiana, have invented and 'discovered-cer- I tain new and useful Improvements .in Methods and Means for FormingOoncrete Structural Members, of: which the following,

is a specification.- 1 ,3. i My 1I1V611t10111 relates to means for formmg concretestructural members,-such ,as

floor members, intended to :support trans:

verse loads,that-is loads theresultantsof which act in a direction-transverse; to, or gat an angle: to the 1longitudinal. /axis of the member; and its objects are to provide a method (and a form) whereby'such mem bers maybe formed at greatly. less cost and more expeditiously than under present practices,'and in which structural concrete members, such, for instance, as beams, may beformed 'in shapes approaching thetheoretie cal beam of uniform strengths, and-thus resulting in thesaving of material and .alsoIv of costly e construction, such as are now necessary to be" dispensing with the use of forms employed to obtain theivarying section of a beam orother structural member of theo-:

" construction." Mounted at suitable intervals retical design. '7

The invention is illustrated in the accompany'ing drawings in which Figure 1, is a vertical cross-section on line 1'1 of Fig. 2 through wha't is known fioors or ceilings and having a slab running from the central column,

form used in molding thelabove construc tion; Fig. 8, a cross-section illustrating the application of the invention to; whatis! known as asolid slab system, Fig. 4, a plan view partly: broken awayof the. form of Fig. 3; Fig. 5,;a cross-section what is e and 1 partly broken away :of-

known as a beam;and'slahssystemf Fig. 6; a plan view I the arrangement shown 11D Fig; 5; I 3

Referring to the drawings, and first to Figs. 1"and'2, 1 indicates central columns adapted to support the radiating concrete slab 2,,which as is herein shown isof the The vertical columns may has =been 'formed-a. up w Fig.1 it will be seen that cantaliver type. be formed by wooden forms 3, of the usual s a mushroom section cantaliver system for supporting;

which slab "isof V cantaliver form; Figw2, a plan-view of the structural member.

r 1 are vertical wooden braces 4, which. are :Be 1t known that I,.-MATTHnws FLE'roHER,

adapted to support cross'beams5, and on which are supported joists '6, preferably of wood, and, which in connection with the structural member of the particular section illustratedin Figs. 1 and 2 are adapted to- V extend radially. from the central column;

Carried bye-these joists-and attached there These flexible-sheaths and the joists-to which I to, preferably by nailing is-a formsheathing 3 7,;cons1st1ngof'duck, canvas or other similar flexlble" and preferably textile materiah.

pansible and collapsible form'Finfwhich the joists are adapted to be spread; apart or movedtogether to stretchthe flexible mater1al :to the necessary degree of tautness to and preservethe necessary rigidity of outproperly support the horizontalbody of con 7 creteewhenthesame is placed on theform line to obtain amember ofithe desired'sec:

tion .withca minimum of waste, and yet atthe same time to permit the sheathing to sag 'sufiicientlyjto obtain, sections in which the depending portions act to obtainadditional stiffness, and strength;

1 To obtain this spreadingl'and stretching 1 action of the formthe same isprovided with, stretcher's, spreaders, struts or wedges at intervals between the j oists adapted to be.

forced against or retracted from adjacent joists." In the particularform of the. inven--- tion illustrate'd inFigs. 1 and 2, cross struts;

8 are employed between the joists at suitable intervals :for the purpose of forcing the}.

same apartcto suitably stretch the canvas so as to effectively 7 support .',the concrete when; applied thereto, Duringflthestr etching. op i eration .the shei ihil gis left unnailed at; some convenient joist so as, to take upthej sag, and after it "has been, finally stretched;

the same is nailed to;the last joist. c

It ,willbe-seen that; by this stretching, the canvas the: same provides a, sufficiently,

stiifi andstrong sheathing-for a horizontal 5 great expense now; incurred; in forming conmay be fvery-expeditiously. erected and quickly knocked down aftenthe structure i By. referring to At the same-time; the,

65 1 they are attached'constitutetogetheranfexanother advantage of this method is that it enables abendingstress resisting member, such as cantaliver beams to be constructed as a beam of uniform strength and one that approximates the true theoretical shape for such members. arms of the cantaliver aretapered in thickness from end to end. In the ordinary method. of forming. such. structures it is necessary to provide separate stepped'sections having angular walls-betweenithesame in order to permit of the formation of such abeamwv'ith a wooden form. Aibeam of uniform strength (technically so-called) is one' inwhichthe dimensions of the cross sections arev varied in such. az-manner that the greatest intensity of compression at each cross section isthe same,-and also'thei-great est intensity of tension at'each :crossisection' 1s the same. In a -I'Q1IIfOI'CBd:COIlCI8t6 beam this uniformitybe. accomplished by varying the crossesectional' dimensions of the reinforcing steel or thecon'crete; or of both;

The dead weightPof acon'crete member. being an important element in the calculation of its:

strength it is: desirable to eliminate as much unnecessary weight ZLSIJOSSlblEL' Elimination of unnecessary: steel is often impracticable and resultsin any'case in very small Elimination V of unnecessary concrete, however; often results 7 in'great reduction in the dead weight of reduction indead weight.

the member. l/Vhile this'economy hasbeen recognized it is not generallyput into practice because of the prohibitive cost of con structing a form in whichto mold such a' shape. In thecase of a "cantaliver floorbeam designed to carry a uniform: load,"forin stance, the total compressionin the concrete is greatest at the support; diminishin'gf to nothing at the extreme end. It lSgOf course,-

unnecessary and wasteful to use the same cross-sectlonal area of concreteat-the-endof this beam as is required nextthe support.

It'has been found impracticable to'build rigid forms to accomplish this saving,hence: they are seldom used,'and at best 'accon'nplish only part of'possible economies. By the use of'a fiexible'sheathing, however, it

becomes possible to mold such a concrete mem ber accurately and economically bvalining the sheathingvalong thet-rue theoretical line oining the support, andv the extremity of the beam, or in such relation tosuch theoretical lineas to avoid a"forn1ation having material in excess of the necessary amount tdgWe-the required strength to: support a 0614351111 load.

Between the joists, of course,- the canvas will tend to sag somewhat but this saggin'gf is not objectionable except inthe formation of certain types'of ceilings, and 'infact with some cross sections it is desirable to permit the canvas to purposely sag"toiprovide .a roundedsection; Also, suchircapacity to Thus it-will'be seen thatthe neaneas sag may be utilized in some longitudinal sections in forming a varying cross section to avoid the use of unnecessary concrete material Without the loss of stiffness or strength. 7 v e, .7

Inmounti'ng the form,"the canvas or other textile materialmaybe first attached to the joists and then later mounted" upon the vertical supports and then the struts or wedges driven between the joists to'stretch the canvastothedesired extent and the con crete poured upon the flexible sheathing. Or the joists may first be mounted-in placeonrthe vertical supports and then the' canvas stretched over the joists nailed for otherwise 1 attached thereto: and 1 the stretching of the same effected by the suitable spreader membersfi In Figs. 3and'4, the invention: is shown.- applied to the construction of a 'fioor: or 'ceil ing employing What is kIlOWIIEZLSlZhQ SOIId slab system.- In thisarrangem'ent9 is the flexible sheathing, .10 the oi'sts" to Fwh-ich the same is attached andl2 wedging' struts between the joists "adapted for spreading the same to stretch thecan-va'srx 13 indicates the bo dyof concrete a'daptedito' be formed'oni the flexible material to constitute theh'ori- P zontal supporting-member. r

In' E' gs. 5 *and f 6' the invention 'is' shown i '9 5 asapplied to the construction of SliI'llC'f tural member constitutingpart of what is known asa'*beam and slab iSYStGIIL? In this "arrangement. la. is the flexible: sheathing, 15 the j oists and*1 6-thespreader; meni- 10o 'bers and 17 indicatesttheibodyto be formed; In this arrangement it' will bemoticedithat' the flexible sheathing is. permittedto sag=be+ tween :the joists and this saggingw-ill pro-- duce a roundedlower'face-which'will pre': 105 vent spawling at the corners. V

Having .thus describedmy invention, what Izclaimis:- i' v 1. The 'method' aof formingsubstantially horizontally? projected concrete; structural 110 memberswhichiconsistsin forming-the mem-- 7 her with V an- -unbroken base line 1 intermediate the ends: thereof by stretcliingga-fiexible supporting body in "a "substantially:horizontal plane=between supports: at; such tension.- asP; 1 1 5 to produce' 'a molding .surface for a. member; of true'theo'reti'cal shape-for obtainingithe maximum" strength with minimum material; f and then:placingroncretethereon.

2. A form for structural concrete me'm3120 bers" comprising: a flexible "sheathing, rigid supports for said sheathing; and 'stretching members for the sheathingintermediatethe; supports. ,7 I

;3.2A form for concrete structures adapted' '125 forcollapsihilitjz and adjustment-and c m, sisting of sheathing supporting joists, joist supportinguprights and textile-materialat tach'ed to a number of the --joists,-.; and};

I to he driven against the same to force the my hand and seal at indianapolis this. 236.

joists apart and stretch the textile material day of May, A. D. nineteen hnndred and to thereby provide a flexible support for the seventeen;

concrete, Which determines the form of the MATTHEWS FLETCHER. [1,. 5.] I

base of the section and permits of colla'psi- Witnesses: bility of the form. H. P. Doom'rm, In witness whereof, I have hereunto set M. L. 'SHULER.

Copies of this patent may be obtained for five cents each, by jaddressing the Commissioner of Patents, Washington, D. G.

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