US3070845A

US3070845A - Pretensioned multiple span beam system

Info

Publication number: US3070845A
Application number: US11888A
Authority: US
Inventors: David B Cheskin
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-02-29
Filing date: 1960-02-29
Publication date: 1963-01-01
Anticipated expiration: 1980-01-01

Description

Jan. 1, 1963 D. B. CHESKIN 3,0 0,

PRETENSIONED MULTIPLE SPAN BEAM SYSTEM Filed Feb. 29, 1960 2 Sheets-Sheet 1 Figure In p9 rn I m i Figure 2 Figure 3 T e/d e/aed after le s/med 26 33 2 7 Q I I I I l 1]" [I] vBI'I/ [I] z e /e /7 E! 30 W32 n x2e F g ure 4 I! 46 45 l IHI ll 43 m/l g/v roe- David B. Cheek/n ATTORNEY Jan. 1, 1963 D. B. CHESKIN PRETENSIONED MULTIPLE SPAN BEAM SYSTEM 2 Sheets-Sheet 2 Filed Feb. 29, 1960 Figure mm am e.0 b w. m M 8/ Mm 7 e P U a; e WM L 0 r G. I F n m m M s Q Figure 8 Dav/d a. Gbeskin fro/m5) United States Patent Ofiiice Patented Jan. 1, 1963 David B. Cheskin, 407 S. Dearborn, Chicago 5, Ill. Filed Feb. 29, 1960, Ser. No. 11,888 4 Claims. (Cl. 189-37) This invention relates to a multiple beam system providing tension and camber therein prior to its being subjected to loading. More particularly the system provides means for effecting the tensioning in a simple manner during the erection of the integrated system.

A principle object of the invention is to provide a simple method for pretensioning steel beam systems whereby each beam of the system is provided with tension in the top portion thereof prior to use or loading and thus can subsequently accommodate far greater loads than would normally be possible by a simply supported beam over the same span.

A further object of the invention is to provide a simple field assembly system for steel beams where camber and pretensioning is accomplished after placement thereof.

The great advantage of the system is of course that smaller, or lesser depth, beam sections can be utilized to accommodate the given loadings and still stay well within the elastic limits of the sections being used.

The system utilized depends in turn upon the use of at least two adjoining beam section which may form at least part of a building frame, or alternatively, sections which extend over at least two spans and three supports, one of which is an intermediate support.

Briefly the invention may be said to comprise a multiple beam section system providing tension in the top portions thereof and resulting camber, which comprises in combination, means supporting and aligning the ends of adjacent beam sections one with the other, said supporting and aligning means abutting the lower portions of the ends of adjacent beam sections, anchoring means at the extremities of the multiple section system, spaced apart upper portions of the ends of adjacent beam sections, and adjustable tensioning means connecting the spaced apart upper portions of the sections, whereby the tightening of the tensioning means effect tension in the top portions of the sections and resulting camber therein.

In another embodiment the present invention comprises a multiple beam system over a plurality of supports providing tension in the top portions thereof and resulting camber in each, said system comprising in combination, spaced supporting means at the lower end portions of each beam extending over each span, bearing means aligning and abutting the lower end portions of adjacent beams, anchoring means at the outer ends of the terminal beams of a system fixedly connecting the latter to the outside supports of the plurality thereof, spaced apart upper portions of adjacent beams, and adjustable tensioning means connecting the spaced apart upper portions of said adjacent beams, whereby the tightening of said tensioning means effects tension in the top portions of the beams and resulting camber therein.

' As will besubsequently described more completely, various means and devices may be provided to provide aligning and abutting means at the lower end portions of the beams whereby they may press against each other during the pretensioning process. Also, various adjustable tensioning means may be provided to connect the upper end portions of adjacent beams so that one section will pull against the other and resulting tension be effected in each of the series of the system. Generally bolts or clamping means are readily adaptable for use as the tensioning means between beam sections.

Reference to the drawing and the following description thereof will serve to more clearly set forth the method and means for pretensioning a multiple span beam system.

FIGURE 1 of the drawing is a diagrammatic elevational view of multiple beams over multiple supports with suitable connecting means providing pretensioning of the beams.

FIGURES 2 and 3 show modified abutting and connecting means for use over intermediate supports.

FIGURES 4 and 5 illustrate still other abutting and tensioning means for use over intermediate supports as well as sloping beam sections such as might be used in' various roof constructions.

FIGURE 6 shows a diagrammatic elevational view of a multiple section frame, with no intermediate supports, which provides means for pretensioning and cambering the tops of the beam portions.

FIGURES 7 and 8 show still further abutting and connecting arrangements.

Referring now to FIGURE 1 of the drawing, there are shown beam sections 1, 2 and 3 extending over and supported on supporting columns 4, 5 and 6, with the latter two being illustrated as intermediate columns and 4 as an outside column of the row thereof.

The outer end of the terminal beam 1 is bolted or otherwise fixedly attached to the top of the column 4, such as by bolts 7 thru the flanges of beam 1 and the cap plate -8.

Y The inside or interior end of beam 1 and the similar interior ends of beams 2 and 3 are provided with a slight taper and fixedly attached plates 9. The plates 9 may be welded, as shown, bolted, riveted, or otherwise connected to the beams. Each plate 9, in this embodiment, extends above the top flanges of the beam sections and are drilled or punched to accommodate one or more bolts 10 at each juncture between adjacent beam sections. .The sloping beam ends and resulting non-vertically positioned plates 9 permit abutment of facing or opposing plates 9 along their lower edges whereby they may compress against each other as bolts 10 are tightened after. erection and assembly of all beams over all spans, of a given building width. Tapered or beveled washers 11 may be used against sloping plates 9 and under the heads and nuts of the variou bolts 10. In order to erect and align adjacent beam over intermediate supports, suitable holes and rivets or bolts 12 may be used between flanges of the beams and the

column cap plates

13 and 14 over respectively columns 5 and 6. Also, where plates 9 extend above the top of the beam sections and it is structurally desirable or necessary to strengthen them because it is desired to use relatively thin plate sections, then suitable fillet plates, such as 15, may be welded or otherwise connected between the top extensions of plates 9 and the top faces of the beams, such as shown at the ends of beams 2 and 3.

In effecting the formation of the camber and the pretensioning in the multiple span system, it is necessary to place all beam sections across the width of the structure, in alignment, and abutting adjacent sections on their lower edges, as shown in FIGURE 1. Then after assembly, the tightening of bolts may being in a gradual and even manner in order to gradually bring substantially equalized tension to the top portion of all beam members. Preferably, tightening should be carried out symmetrically with respect to a center line of the building or structure. As for example, in the instance of three intermediate supports, the bolts over the supports next to the outside columns or walls should be tightened first and then the bolts over the center support lastly.

FIGURE 2 shows a modified means of effecting abutment and tensioning between two adjacent bearn rnen'l "end"sections"52and"53"are illustrated diagrammatically bers such as 16 and 17 over=supporting column 18 having cap plate 19. In this embodiment thebeam 1 6 has a lower lug'inember' Zit attached thereto and' be'am '17 has a'lower lug 21 attached to it.- Each of the lugs" be bolted to the'column by bolts 22 and providefneans'forf the effective abutment of the lower portions of th i n 'ds" of the'adj'acent

beams

16 and 17, with compressive forces carrying throughthe top end of the'colu'mn 1- 8 andplfate: 19/"End' plates 23 are"attached to t'hespaced apart ends of the two

adjacent beams

16 and 17 andftheir upper' portionsare' provided with suitable holes for"bolts' 24 such that tension may be effected betwe'en"fa" aime top portions of the beam members. 'In'this modified designfor' connecting the beams of the 'nmm wn ani' systemgthe te'nsioningmeans 'are' maintained just"below the top flanges of the beams in order to provide a'i'substantially smooth 'top surface to the system.- -A'lso, if

desiredg thebolts or other tensioning-means 'need -[bc used-only temporarily at the beam'junctu're's." For-'ex -f ample, a plate 25 may be Welded across thetop'o i'the' end ofbeams'16 and 17 'after pretensiohin'g the"b'ea'ms.

and not in any detail or actual scale. The lower ends of the combined column and

beam sections

52 and 53 may be connected to lowerzbases or

foundations

55 and 56 bytanchor;.-- holts onpivotedmeans. The beam Section 54 is provided Withi end plates '7, while the beam portions ot-ysections 52 and 53'"Lire-providedwith, re-

spectively, phrases and 59. Such plates maybe welde or otherwise attached'tt') the beamse'ctions and of course should be bent or angled to provide abutment at their iow r"pbrtioiis' ahd "spacing at "their; upper "portions. Siippor mg p1 t'es areprovided a t t he juncture of beam enaseetions' whereby theseintermediate 61, 'with beveled washers '62"under'the he'ads and nuts It may be further pointed out, in' an-auernanve type of :assemblyoperation, that suitable removable adjustable clamping 'means" may be usedto pull 'tlie tofpor tion of one beam againstthe other-"inlieu o'f bolts 24.; Themwhen the desired tension and camber-is put irito the top portions of all of the beam'spthevarious plates 25. at all: junctures can be field-Welded-or bolted into place and maintain-the s'ystemunder th'e'desird -p tensioning. 1

In FIGURE 3 end ;portions.of beams-of system =are shown in another manner, with.;beams26and 27-resting on 'brackets"28- near. the. topof column 29. The ends of the beams "26" and ,27- are --notched tofit over the top of column 27' and the .-cap-plate 30.- Shaped end plates 31 are welded orotherwise fixed to the ends of the beams'26 and 27. Bolts32 serve to attach the beams to-the 'braclc'et's 28, whereby-compressive forces can carry thru the t0p otthe column from one beam to the otheryand bolts-33 through the spaced apart portions of the-end plates'*31 provide for tensioning the top portions of the-

adjacent beams

26 and 27. Here again the bolts 33 are shown below the top surface of the beams to provide an umobstructed top surface for the beam members. I

FIGURESA and 5 illustrate sloping beam arrange ments, with downwardly sloping ends of

beams

34 and 35 beingsupported on column36; and'the upwardly sloping ends of

beams

37 and 38 are supported on a column 39. In FIGURE 4, the bottom ends of

beams

34 and 35 rest on cap plate 40 and against the edges ofbearring plate 41 which in turn is-attached to the plate 40. The-beams may be held in alignment-at the column and against the bearing plate 41 by supporting clips 42 and bolts 43. Aplate 44 on each. of the spacedapart' ends of

beams

34 and 35 provide means for placing-bolts 45 and tensioning the top fibers=of these adjoining-beams and also effecting the desired camber .in the beams.- Suitable beveled washers 46 may be used-betweenthe sloping plates '44 and the heads and nuts of bolts 45;

In FIGURE 5, the bottom ends ofbeams 37 and ;38- rest on and are aligned by clips or brackets 47=.and connecting bolts 48 at the topof the intermediate column: 39. In thisinstance plates 49 at the-ends of the beam members are shaped and fixedly attached to said-beams so. that they may directly abut and 'pushcag'ainst eachother along theabottom portions ofthe beams; Thespaced aparttop portions of the-plates 49 are provided with holes to accommodate bolts 50. Here again-bev-v eled .washersSl may be used betweengtheslopping plates:

49 and the headsand nuts .of the bolts:50.; .1

comprising-v end sections 52: and- 53 and center beam section 54, after pretensioning has been applied. The

of the drawing, abutment of th'e lowe'r' thereofif 'are ovided-betvveen end-plates of the beam sections' to iii-turn, provide tensioning means at the junc'tt'rresfi' After 'tlie 'e're'ction" and" assembly of th sections, spaces are left between the plates at the ends of the heam 'sectiofis; and 'the"bolts 61 are drawn to provide a' proper tensi'oningi' This'tensioning results in tension in the 'ins'ide' of the 'kneesdf sections-52 and-53 and inthe' top' of 'section 54',-whicli= is "opposite to the effect of the' -load to be subsequently applied"inthe use of the s'tructure: -Abutmentrof the endplates" 57=-with plates 58 and 59- may be accomplished accurate'design and fabrication or' by suitable shirnsu ."ImFIGUREKI aI modified form of--' juncture is shown which. may the: used between beam sections; I such as in a-.-fram e.-:o-the type ofaFIGURE 6 where no =intermedi-' ate columns or supports -are=-used.'='-Beam sections 52" andy54' -are;provided-'witlr olfset =

plate sections

63 and 64,-respectively;:-: A .horizontal portion'of plate 63 provides=-a'sliding supportzor base for a:horizontal portion of-plate64 wh reby. beam section 54' maybe temporarily supported. i Bolts'65 .between the upper vertical spaced portions ofplates 63;. and :64 provide means-for connecting and tensioningtthe beamsections. Also, as in the other embodiments of -.the present invention, the

' loweravertical portions. of ,the

plates

63 and 64 are conv tions of the-beam; sections..

structed and arranged such that these'lower portions abut to .leave a space between the upper portions whereby pretensioning may be accomplished in the upper por- In FIGURE 8 of the drawings there is shown a connection of a beam section 66 with an end support or column 67 where :itmaybe desired to effect .tensioning' from both: ends of an end beam of a series. Beam 66 is provided with a sloping plate 68 and column 67 is provided witha sloping cap plate 69. These plates and g'app'ingv or; spacingof theuouter portions. Boltsare .cons tructed or shaped such that in their welded attachment, or other. connection, to theends of the stnuc-- turalp mper m i abutment of the inside portions were provided at the outer portions of

plates

68 and 69 "to vprof/id'eihe. desired tensioning in the top of beam 66. The beam;. 6 6 ,-is-hel d in alignment at .the column 6 7 by supportingclip 71 and bolts .72.

'In'this' latter embodiment, as well as. with various of the other modifications, =it is-within the scope of the viding the desired pretensioning and camber to arse adjustable tensioning means ,other than threaded bo lts, as briefly set forth in connection with the description of,FfGURE 2. The tensioning means J J the nature ,o f.a C-clamp having adjustable threade "tak up; means, or alternatively ahydraulically operatdic ping means. Such means are used only temporarily during the tensioning step when it is desiredf o have fiired, straps on the plates, such as plate 25 The framesystemof FIGURE 6-shows three sections J Ph t'is i tfltst ed necessary to illustrate such removable types of pulling or clamping means in the drawing.

I claim as my invention:

1. A multiple beam section system providing tension in the top portions thereof and resulting camber, which comprises in combination, at least two separate beam sections, means supporting and aligning the ends of adjacent beam sections one with another, means abuting the lower end portions of beam sections, separate individual support and anchoring means at the outer extremities of the outer beam sections of the multiple section system, an end plate attached to the abuting end of each beam and spaced apart upper portions of the ends of adjacent beam sections, and separate individually adjustable tensioning means connecting with and between said spaced upper portions of said sections Whereby the tightening of last said means incorporates tension and camber in the top portions of said beam sections and ties said sections together in a continuous system.

2. A multiple beam system over a plurality of supports providing tension in the top flanges and resulting camber in the plurality of beams, which comprises in combination, a plurality of beam sections extending longitudinally in a multiple span arrangement, means supporting the bottom portions of each end of each beam and at each intermediate support, bearing means aligning and abuting the lower portions of adjacent beams, separate individual support and anchoring means at the outer ends of the terminal beams of the system to the outside supports of the plurality thereof, an end plate attached to the abuting end of each beam and spaced apart upper portions of adjacent beams, and separate individually adjustable tensioning means connecting with and between said spaced upper portions of said adjacent beams, whereby the tightening of said tensioning means effects tension in top portions of the beams and camber therein and ties said beams together in a continuous system.

3. The beam system of claim 2 further characterized in that at each intermediate support the lower flanges of said beams abut one another and the upper end portions of said beams are spaced apart and are provided with opposing end sections which in turn have opposing holes adapted to have threaded bolts connecting therebetween, whereby said bolts may be tightened to provide tension along the top portions throughout the lengths or said beams.

4. The beam system of claim 2 further characterized in that fixedly attachable tie means are provided across the upper portions of adjacent beams in addition to said adjustable tensioning means.

References Cited in the file of this patent UNITED STATES PATENTS 121,374 Jackson Nov. 28, 1871 732,164 Burdon June 30, 1903 2,822,068 Hendrix Feb. 4, 1958

Claims

1. A MULTIPLE BEAM SECTION SYSTEM PROVIDING TENSION IN THE TOP PORTIONS THEREOF AND RESULTING CAMBER, WHICH COMPRISES IN COMBINATION, AT LEAST TWO SEPARATE BEAM SECTIONS, MEANS SUPPORTING AND ALIGNING THE ENDS OF ADJACENT BEAM SECTION ONE WITH ANOTHER, MEANS ABUTING THE LOWER END PORTIONS OF BEAM SECTIONS, SEPARATE INDIVIDUAL SUPPORT AND ANCHORING MEANS AT THE OUTER EXTREMITIES OF THE OUTER BEAM SECTIONS OF THE MULTIPLE SECTION SYSTEM, AN END PLATE ATTACHED TO THE ABUTING END OF EACH BEAM AND SPACED APART UPPER PORTIONS OF THE ENDS OF ADJACENT BEAM SECTIONS, AND SEPARATE INDIVIDUALLY ADJUSTABLE TENSIONING MEANS CONNECTING WITH AND BETWEEN SAID SPACED UPPER PORTIONS OF SAID SECTIONS WHEREBY THE TIGHTENING OF LAST SAID MEANS INCORPORATES TENSION AND CHAMBER IN THE TOP PORTIONS OF SAID BEAM SECTIONS AND TIES SAID SECTIONS TOGETHER IN A CONTINUOUS SYSTEM.