US3162280A

US3162280A - Falsework girder

Info

Publication number: US3162280A
Application number: US114215A
Authority: US
Inventors: Hinze Otto
Original assignee: HICO CORP OF AMERICA
Current assignee: HICO CORP OF AMERICA
Priority date: 1960-06-07
Filing date: 1961-06-01
Publication date: 1964-12-22
Anticipated expiration: 1981-12-22

Description

Dec. 22, 1964 o. HlNzE FALsEwoRK GIRDER Filed Junel 1. 1961 2 Sheets-Sheet 1 INVENTOP Off@ ///A/Zf Dec. 22, 1964 n o. HlNzE 3,162,280

FALSEWORK GIRDER Filed June l. 1961 2 Sheets--Sheetl 2 MMQ United States Patent O 3,162,286y FALSEWRK GIRDER Otto Hinze, Hannoverdleefeld, Germany, assigner to Hice Corporation of America, New York, NX. Filed .inne ll, 196], Ser. No. lldl Claims priority, application Germany June 7, 1960 13 Ciaims. (Cl. 189-37) The invention concerns a method of producing falsework girders, preferably telescopic falsework girders, and falsework girders produced by means of this method.

According to one feature of the present invention there is provided a method of producing falsework girders or girder portions especially telescopic falsework girders comprising at least one outer and inner girder adapted to be telescoped one in the other, which are adapted to be locked with one another bymeans of a catch element, characterised by arranging concentrations of material at the flange-like upper webs and lower webs of the girder or girder portions.

According to another feature of the present invention there is provided a falsework girder, preferably telescopic falsework girder comprising at least one outer and innergirder adapted to be telescoped one in the other the girder or the inner and outer girder having concentrations of material at the flange-like upper webs and the lower webs.

In a preferred embodiment the invention concerns a telescopic falsework girder comprising at least an outer and inner girder each adapted to be slidably disposed one in the other, which are adapted to be locked relative to one another in any extended position by means of a fastener e.g. a cotter.

In an embodiment of the girder comprising an outer and an inner girder supporting brackets are arranged on the outer ends of both girder portions. However it is possible to use an outer girder with two inner girders which are displaceably mountedon the ends thereof or anainner girder withftwo outer girders which are displaceably mounted on the ends of the inner girder. In those alternative embodiments supporting brackets are provided at least onev the extendible girder ends. Besides cotters, screws, eccentrics lor similar clamping means are known and'can be used as the fastener.

It is known moreover to impart-to the girder during productionor before being laid a camber corresponding to the deflection expected when'loaded. The arrangement of such a camber canbe provided in special embodimentsk of :the girderin accordance with the invention.

Telescopic` falsework girders have hitherto been made practically without exception of steel and constructed inthe form of sohld-webbedf and latticegirder or as a mixture of systems, inl which solid-webbed and lattice elements are used alternately.

Known solid-webbed girders are either made of rolled or folded' sheettand have uniform thicknessof material. Itis known moreover to weldA together solid-webbed girders of individual profiles. Cup-shaped or triangular profiles. are thus used' for the upper flange, whilst the lower ange in mostv cases consists of angle and round steel.

Lattice girders aremore dihicult to make owing to necessary` weld connections between the flanges and the web members.

. Production of these known falsework girders is comparati-vely' expensive because considerable manuallabour or extensive mechanical production equipment is required.

Attempts to introduce a falsework girderof light metal constructed of tubular profiles having a circular crosssection-was not successful because ysuch girders are not equal to the requirements demanded therefrom. With the small tolerances even slight deformations or denting lead to jamming` of the girder sections slid one in the other. Moreover considerable deflections made intermediate supports at comparatively short intervals necessary.

The invention is based on the problem to provide a novel kind of girder which, for example, improves girders of steel and also makes it possible for them to be constructed from other materials. This problem is tackled in accordance with the invention byl the fact that the girder or girder section is cast by arranging concentrations of material at the upper flange and lower flange.

In accordance with a preferred embodiment the igirders.

or girder sections are extruded whilst simultaneously material is displaced at the upper flange and the lower flange. v

In accordance with a preferred embodiment the girders or the girder sections are made from plastics material, in this connection it is advantageous to embed inserts-of extension resisting material in the concentrations of mate rial of the lower flange at least.

The invention includes the manufacture of the girder or the girder sections of metal, preferably light metal, by arranging concentrations of material in the upper flange and the lower flange. In accordance with the. invention gibders or girder sections are made from steel, for example.

The method of production in accordance with the invention leads to surprising price reduction of the girder, whereby more especially by the concentration of-material at certain points, girder constructions are obtainable which in respect to material properties have greatly increased resistance to extension.

The falsework girder produced in accordance with the method is distinguished by the construction of the girder,

or the inner or outer girder of extruded sections having material concentrations in upper flange and the lower flange. This results in a construction of low weight since the material is arranged at the points where forces occur, i.e. compressive forces in the upper flange andtensile forces in the lower flange. The webs of the sidewalls have the minimum wall thickness necessary to avoid denting.

When arranging thev material agglomerations in the region of the upper and lower flanges a preferred embodiment of the invention provides that the agglomerat-ion in the region of the upperflange amounts to 10%' more than in the regionA of the lower flange.

In accordance with a particularly preferred embodiment of a telescopic falsework girder the girder sections, i.e. atleast atan outer andV at least at an inner girder in the region of the upper web or upper flange there are provided two sliding surfaces complementing one another for the load transmission.

In accordance with a particularly preferred embodiment of the invention the sliding surfaces are provided in material'concentrations in the upper ange. With advantage the sliding surfaces and the material concentration in the region of the upper flange are spaced apart. With such distribution of the masses there is obtained a. particularly favourable resistance against lateral forces. In this embodiment the invention provides for the sliding surfaces provided with material concentrations to be inclined outwards and downwards on either side of the longitudinal centre plane of the girder.

Herewith there is provided a telescopic girder the outer and inner girder of which are supported on sections of sliding surfaces each forming a key, the upper flangesof the outer and'inner girder are kept free of the forces transmitted between these girders and, for example, guided free of contact one against the other.y The key-like arrangement ofthe sliding surfaces on either side of the of the outer and the innerggirders.

material for lthe construction it is advantageous for the inner girder to besubstantially shaped as an isosceles` Y triangle' arranged with the acute angle pointing down- 3 longitudinal centre plane thus causes a centering of the outer and inner girder, besides the lower flanges being centered relative -to one another, at the same time.

The angle of the sliding surfaces is advantageously so dimensioned that, seen in cross-section, only compressive.,

forces occur in the upper web of the inner girder. A further construction of the invention provides that the forces extending in all sections of the inner girder in the transverse plane are compressive forces exclusively.

The sliding surfaces of the inner and outer girder are preferably arranged on either side of the longitudinal centre plane and beneath a horizontal'plane determined by the upper flange of the girder section concerned, and the angle of the sliding surfacesis so. dimensioned that the components of the resulting forces in the transverse direction of the girder in the flange-like upper web produce compressive forces. The inner girder is preferably cons'tructedywith Y-shaped webs beneath the flange-like upper web, the sliding surfaces being disposed at the upper ends of the V-shaped portion of .the webs.

. The angle of inclination of the sliding surfaces is conveniently disposed between 45 and 10 relative to the horizontal. This angle of inclinationis preferably limited y betweenv 40 and 20vrelative to the horizontal. The pre- A desirable feature of the invention provides a girder of a plastics material. A girder in accordance with the invention may be produced, for example, of arnaterial based on polyvinyl chloride. Preferably a material formed of PVC or PVC based polymers is used.- The invention moreover concerns other suitable plastics materials too such as, for example, polystyrene. It'is also advantageous to use a plastics material based on polyamide.

The invention herewith Vprovides advantageously an insert of material considerably resistant to extension, such as steel in the material concentrations in the lower flanges When using plastics wards, the inner space thereof being divided by means of honeycomb-liken arranged webs.

,The invention willbe described further, by way of example, with reference to the accompanying drawings in v which;

FIG. 1 is a cross-section through an outer girderY in ac' cordance withV the invention; l

FIG. 2 is a cross-section through a cooperating innery YFIG.V 7 is a force diagram shown Yschematically and., only partly for a girder construction in accordance; withl .Y

FIG. Y5. n y l Y The outer girder shown in'FIG. 1 has a prolle which, in the operational Vprosition,ris constructed substantially in struoted of a plastics material, for an outer girder section Y ofthe 'girder in accordance i the form of an inverted

U having webs

1, 2 tapering downwardly inwardly. The webs are constructed as solidwebbed elements but they may be perforated. On their upper ends the webs are connected by means of an upper flange 3. At their lower ends the webs have concentrations 4, 5 of material whose inner surfaces 6, 7 are substantially parallel 4and serve as guides for the lower Web of the inner girder still .to be described.

It is evident that the

webs

1, 2 at their upper ends are connected with the upper flange 3 by means of concentrations of material 8, 9. The outer sides 10, 11 of these sections are preferably inclined relative to the longitudinal centre plane whichis indicated by the line 12 thus caus ing it to form an obtuse angle relative to the

webs

1, 2 and the upper r'flange 3. The concentrations 3, 9 protrude into the interior of .the girder. These material concentrations have substantially -

vertical wall sections

13, 14 extending downwardly from the upper ange 3 and

wall sections

15, 16 sloping obliquely downwardly to the outside in continuation of the

sections

13, 14. The

wall sections

15, 16 always assume the same angle relative to the horizontal.

The material concentrations 8, 9 are together greater than the material concentrations 4, 5 in the lower flange. The described profile may be produced by extrusion, it being possible to provide cambers of girder.

The drawn-in open side of the outer girder profile is bridged over by at least one U-shaped stirrup 17 which engages over the outer sides of the material concentrations 4, 5 and may -be secured by means of

screw bolts

18, 19 to the material concentrations. It is possible to use threaded insert bushes 59, 60, for these bolts so that small dimensions may be obtained when using a comparatively soft material. If necessary, the U-shaped stirrup 17 may be attached by welding.

The material concentrations 8, 9 are spaced from one another substantially by the width of the girder. This provides a good rigidity laterally. The distribution of the material concentrations in the upper and lower anges moreover provides a high load-bearing capacity for the girder in relation to the quantity of material used.

j FIG. 2 shows an embodiment of an innergirder for use with the outer girder of FIG. 1. This inner girder has a Y-shaped web portion 20 on the vertical web of which there is arranged at the bottom a material concentration 21 and at the top outer edges thereof conouter ends of theV uppertiange 24 and the upper ends of inclined webs 2S, 26 have sliding

surfaces

27, 28

ycorresponding to the

surfaces

15,16 and also vertical limiting

surfaces

29, 30. The distance between the

surfaces

29, 30 is smaller'than the distance .between the

surfaces

13, 14. 'Ihe angle of inclination of the

surfaces

27, 28 corresponds to that of the

surfaces

15, 16. The height of Vthe surfaces *13, 14 is preferably lessY than that of the

surfaces

29, 30. This ensures that the load Vtile in accordance with FIG. 2 may be produced by extruding. Y

VTheprotiles according to FIGS. 1 and 2 maybe produced'ofgsteel, or `of light metal or. of a plastics material. When produced of a plastics material, a construction according'to FIGS. .3 and 4 is preferred, of which FIG.

fshows .a modied form ofinner girder. It is pointed out thattheinner girder in accordance with FIG. 2 may alsoY be made'of plastics material, whereby inthat case,

as :far as possi-ble, an insert 61 resistant to,v extension is arranged in the manner yet to be described in the region of the lower material concentration 21.

The profile in accordance with FIG. 3 consists substantially of an isosceles triangle, the acute angle of which faces downwards and extends into a comparatively wide web 32. Between the

lateral webs

33, 34 and also the flange-like -upper web 35 there are arranged honeycomb-like intermediate webs which, for example, in the upper region comprise a hexagonal honeycomb 36, intermediate webs 38, l39, 40 and 41 extending from the corners to the

side webs

33, 34 and lone intermediate web 42 extending downwards and wh-ich is forked to engage with the

side webs

33, 34. Attention is drawn to the fact that an alternative intermediate web arrangement is also possible within the scope of the invention. The object of the arrangement of intermediate webs is to serve as .a central support of the individual webs for the purpose of increasing the resistance to denting when constructing of comparatively soft materials. The upper region of web 32 is provided with a hollow space 43. In its lower portion it has an insert 44 resistant to extension. The insert resistant to extension is preferably made of steel and is profiled to obtain a good adherence. It is possible, for example, to use transversely ribbed steel, I-steel, twisted steel strands and the like which at all points ensure an adhesive bond in longitudi* nal direction between the material in the lower region of the web 32 and the insert. Attention is drawn to thev fact that it is also possible to provide corresponding inserts possible of different dimension in special embodiments also in the region of the material concentrations at 45 and 46. These material concentrations are accordingly proled at their outer surfaces with the surfaces corresponding to the surfaces 27 to 3i).

In the construction of plastics material the outer girder, which is adapted to have a cross-sectionalshape in accordance with FIG. 1, is provided in the region of its lower material concentrations 4, 5 preferably with inserts 47, 48 corresponding to the insert 44. It is possible then, for example, to provide equally or weaker profiled inserts `also in the material concentrations 8 .and 9 in accordance with FIG. 1.

Attention is drawn to the fact that a feature of girder construction with inserts consists in that the inserts are rigidly connected to supporting 4brackets or end pieces made of stronger material than the remaining girder portions. The end pieces, for example, may consist of steel.

FIG. 5 shows .an assembly of the girders according to FIGS. 1 land 2. It is perceptible that the inner and outer girder are supported one against the other in the region of the

inclined surfaces

15, 16 with 27, 28. The wedge-section-like abutment of these surfaces thus at the same time ensures centering of the girder portions in the region of the flange-like

upper web

3, 24, thus causing the

surfaces

13, 29 or 14, 30 to be guided without pressure on one another. The stated height dimensions of the

surface

13, 14 relative to the surfaces 29, 39 thus ensure that also the ange-like

upper web

3, 24 are caused to abut against one another with the surfaces facing one another without pressure or slight pressure, preferably with a slight clearance.

It is moreover perceptible from FIG. 5 that between the material concentrations 4, 5 at the lower ends of the lateral webs of the outer girder there is provided a 'cctter 49 indicated only in the drawing, for the purpose of lockingthe inner girder and outer girder by pressing the surfaces. 27, 2S against the

surfaces

15 and 16. The cotter is expediently of wide construction to cause it to abut with its sides Aagainst the surfaces 6, 7 of the material concentrations 4, 5. Thus shearing stress of the U-shaped stirrup 17 will be prevented if the cotter jams when it is driven home. The rounded construction of the lower surface 31 at the lower material concentration of the inner girder thus abuts against a corcording to FIG. 5. The lgirder construction in accord ance with FIG. 6 only comprises an inner girder 51 and an outer girder 52. Identical parts as in FIG. 5 are designated by the identical reference numerals. The outer ends of the girder portions are each provided with supporting brackets S3, 54. These supportingrbrackets may consist of steel. More especially when using inserts in accordance with FIGS. 3A and 4 it is possible, as shown` in broken lines at 5S and 56 of the drawings, that such inserts may befextended beyond the lower chord of the corresponding girder portions when a fixing of the insertsl to the supporting brackets is. provided.

FIG. 7 shows the schematic force distribution by transmitting the loading forces via the surfaces 15, I6 or 27, 28, which are shown in FIG. 7 of the drawing. The forces transmitted via these surfaces extend vertically relative to these surfaces :and each have a resultant corresponding to the arrows 5.7, 58 or 59, 60.

For the inner girder it is perceptible that the resultant 59, Gti is composed of the

components

61, 62 or 63, 64. The components 62, 64 cause the flange-like upper web 24 to be iinpinged upon with compressive forces corresponding to the arrows shown in the drawing. The construction with the

surfaces

27, 28 below the plane of the angelike crosssgirder 24 thus according to the proportion of the vertical distance between these surfaces and the. plane of the upper web produces a bending moment, the magnitude alongside the width of the flange-like upper web 24 depends upon the componentsl, 63. It is therefore evident that by inclining the

surfaces

27, 28 the kind of loading the flange-like upper web 24 can be selected, this'inclination however having to be selected expediently in such a manner that the compressive forces shown in the drawing occur in this upper web.

Compressive forces also occur under the circumstances shown in the webs 25, 2d.. It is understood that the force distribution depends not only on the inclination of the

surfaces

27, 28 but also upon the angle 66 between the

webs

25 and 26 and adapted to be selected for the production.

The outer girder in accordance with corresponding considerations absorbs in the ange-like upper web 3 and also in the

rst webs

1, 2 tensile forces according to the arrows shown in the drawing. i

With regard to the construction of plastics material, for example, the sliding surfaces on the outer or inner girder may be metallizcd. Moreover the invention also provides combined girder constructions, according to which the outer and inner girders are made of different materials. For example, the 4inner girder wherein an insert is provided in at least the lower material concentration is adapted to be made of plastics material, whilst the outer girder is made of metal.

What I claim is:

1. A telescopic girder construction comprising at least one outer girder section and at least one inner girder section adapted to be telescoped one into the other, and means for locking the girder sections together, the outer girder section including a transverse upper web and side webs extending downwardly from the edge portions of said transverse upper web, characterized by the provision of inclined plane bearing surfaces at the inside corners where the upper web is joined to the side webs, the inner girder section Iincluding a transverse upper web and side webs extending from edge portions thereof, the upper corners of the 4inner girder section having slidabie engagement with said inclined plane bearing surfaces of the outer girder section, and a clearance being provided between the transverse upper webs of the outer and inner girder sections.

i 2. A telescopic girder construction according to claim 1in which the -inner girder section has inclined planev bearing surfaces adjacent the area of slidable engagement between the twoV girder sections.

3. A telescopic girder construction according to claim 2 inl which the angle of said inclined plane bearing surfaces is predetermined to produce compressive forces in said transverse upper web of the inner girder.

4. A telescopic girder construction according to claim 2 in which the angle of said inclined plane bearing surfaces to the horizontal is between 45 and 10.

5. A telescopic girder construction according to claim 2 in which the angle of said inclined plane bearing surfacesV to the horizontal is between 40 and 20. j

6. A telescopic girder construction according to Yclaim 2 in which the angle of said inclined plane bearing sur- Y faces to the horizontal is approximately 30.

7. A telescopic girder constructionaccording to claim 2 in which said outer girder section has thickened lower edges with longitudinally extending strengthening inserts embedded therein.

8. A telescopic girder construction according to claim 2 in which said 4inner girder section has a thickened lower chord with a longitudinally extending strengthening insert embedded therein. K

9. A telescopic girder construction according to claim 2 in which supporting brackets are axed to outer ends of the respective girder sections and at least one longitudinally'extending strengthening insert is embedded in each girder section, said strengthening inserts being secured to the respective supporting brackets.

` l0. A telescopic girder construction according -to cla-iml 11. A telescopic girder construction according to claim I 2 in which the vinner girder section has a hexagonal honeycomb-web in the interior thereof and intermediate webs extending to said transverse upper Web and side Webs thereof, and an intermediate web bifurcated at its end, the bifu'rcated ends of which are connected to the side webs in the lower region of said girder section.

. 12. A telescopic girder construction ,comprising at least one outer girder section and at least one inner girder section adapted -to be telescoped one into the other, and means for locking the girder sections together, the outer girdersection including a transverse upper web and side webs extending downwardly from the edge portions of said transverse upper web, characterized by the provision of thickened upper corner portions at the corners where the upper web is joined to the side webs, the inner girder section including a Vtransverse upper web and side webs extending from edge portions thereof, the upper corners ofthe inner girder section hav-ing slidable engagement with said thickened corner portions of the outer girder section, the. inner girder section having thickened upper corner portions adjacent the area of slidable engagement betweenthe two girder sections7 the outer girder section comprising inclined lower surfaces and substantially vertical surfaces extending upwardly from the inner edges of said inclined lower surfaces, and the thickened upper corners of the inner girder'section comprising inclined upper surfaces and substantially vertical surfaces extending upwardly from the inner edges of lsaid inclined upper surfaces, the incl-ined surfaces' of the two girder sections having a mating `engagement and the opposed substantially vertical surfaces of the two girder sections having a clearance between them, the engagement of the inclined surfaces at the upper corners of Athe girder sections centering the inner girder section within the outer girder section.

13. A telescopic girder construction according to claim 12 in which the innergirder section has, a transversely rounded lower edge engaging'a complementary rounded surface of said locking means whereby the centering ac- .-tion of the inclined surfaces at the upper corners can take place With free alignment of the two girder sections.

2,988,182 f Campbell June 13, 1961 n '3,023,863 Klaus Mar. 6, 1962

Claims

1. A TELESCOPIC GIRDER CONSTRUCTION COMPRISING AT LEAST ONE OUTER GIRDER SECTION AND AT LEAST ONE INNER GIRDER SECTION ADAPTED TO BE TELESCOPED ONE INTO THE OTHER, AND MEANS FOR LOCKING THE GIRDER SECTIONS TOGETHER, THE OUTER GIRDER SECTION INCLUDING A TRANSVERSE UPPER WEB AND SIDE WEBS EXTENDING DOWNWARDLY FROM THE EDGE PORTIONS OF SAID TRANSVERSE UPPER WEB, CHARACTERIZED BY THE PROVISION OF INCLINED PLANE BEARING SURFACES AT THE INSIDE CORNERS WHERE THE UPPER WEB IS JOINED TO THE SIDE WEBS, THE INNER GIRDER SECTION INCLUDING A TRANSVERSE UPPER WEB AND SIDE WEBS EXTENDING FROM EDGE PORTIONS THEREOF, THE UPPER CORNERS OF THE INNER GIRDER SECTION HAVING SLIDABLE ENGAGEMENT WITH SAID INCLINED PLANE BEARING SURFACES OF THE OUTER GIRDER SECTION, AND A CLEARANCE BEING PROVIDED BETWEEN THE TRANSVERSE UPPER WEBS OF THE OUTER AND INNER GIRDER SECTIONS.