US3431694A - Rhombic girder - Google Patents

Description

March 11, 1969 E. M.IHUNNEBECK 3,431,694

RHoMBIc GIRDER Filed March lO, 1966 Sheet g of 4 RHOMBIG GIRDER Filed March 10, 1966 Sheet Fig.

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March 11, 1969 E. M. HUNNEBECK 3,431,694

RHOMBI C G IRDER Filed March 10, 1966 sheet 3 of 4 L J L l March l1, 1969 E, M.|1UNNBECK *3,431,694w

RHOMBIC GIRDER Sheet Filed March lO, 1966 In ven/alf.

United States Patent H 51,402 U.S. Cl. 52-695 7 Claims Int. Cl. E04c 3/02, 3/30; E04h 12/00 ABSTRACT F THE DISCLOSURE A rhombic girder having a plurality of individual parts,

which comprises an upper boom and a lower boom and a rhombic framework disposed between the upper boom and the lower boom. Each of the booms includes a plurality of individual parts abutting each other. One of the parts of the lower boom is provided at its end with a pin having an outer face extending parallel to the longitu-` dinal axis of the lower boom. Another of the parts of the lower boom adjacent to the one of the parts provided with a recess disposed opposite the pin and has an outer` face disposed complementary to the outer face of the pin', so that cross-forces of one of the lower booms are transmitted to another of the lower booms. Clamping means holding together the lower booms in the longitudinal direction, and distancing holders of variable length connecting together pressure-fast the lower booms.

The present invention relates to a rhombic girder composed of a plurality of individual parts and in particular to a joint connection in the lower boom of girders composed of a plurality of individual parts, in particular of rhombic girders.

Compared 'with such girder structures, in which the struts between the upper boom and the lower boom are disposed about zigzag and V-shaped, respectively, and form triangles, rhombic girders, in which struts are disposed crosswise relative to each other between the upper boom and the lower boom and thus rhombs standing on their points are formed between the strut crosses, have the great advantage that due to the crossing of diagonal struts, the collapsing length of the diagonal struts exposed to pressure is reduced to about half. For this reason, rhombic girders are suitable for the manufacture of supporting structures, particularly advantageously as girders on two or more supports. If such rhombic girders are applied as provisional supporting structures, for instance, for the setting up of provisional bridges or in the setting up of scaffolds, the supporting structure must be divided into individual elements and assembled on the structural side. The individual parts are constructed such, that one of the diagonal struts engages each end of the upper boom and of the lower boom, respectively. In order to maintain the character of the rhombic framework, it is required during the assembly of the individual parts, that the upper boom and the lower boom are abutted by two part elements, so as to be connected together of a rhombic framework girder in the framework syste-m points, such that the upper boom connection and primarily also the lower boom connection is capable of transmitting normal forces, that is, pushing or pulling forces effective in the longitudinal direction of the boom, and cross-forces, that is, forces effective crosswise to the longitudinal directon of the boom. For this reason, in all known rhombic girder structures the abutting connections are designed such, that the booms are rigidly and intimately connected with each other by a direct contact connection. This has the drawback and the difficulty, that in order to achieve a straight girder, an

faice extremely precise manufacture of the individual parts is required. If camber of the girder is required, the known rhombic girders composed of a plurality of parts have the further appreciable drawback, that the camber is not Varlable, that is during the assembly of the individual parts no selective upwardly extending design can be provided for the rhombic girder. The known rhombic girders are thus not suitable for the manufacture of scaifolds, for instance, vas a supporting girder for the manufacture of bridges or other heavy steel-concrete structures, unless for the compensation of the occurring elastic bending through upon application of a load, a bottom lining of the boarding mounted on the girder is provided, which boarding must be increased towards the center of the girder, in order to give to the boarding itself an upward vault design. Such measure leads, however, technically to difficulties and requires appreciable expenses.

In so-called framework girders, for instance, in the conventional girders with zigzag-shaped disposed struts between the upper boom and the lower boom, the so-called camber of the girder can be obtained by coupling nuts by which the lower boom of the individual parts of the girder are connected together and which can be expanded or shortened, so that the girder composed of two or more individual parts can be cambered, in order to obtain a plane bottom view of the structure by shortening the coupling nuts and upon finishing of the concrete ceiling or the like it can -be lowered again by extension of the coupling nuts, in order to remove it from the supports without any difficulty, on which supports it rests at its ends. This expedient for the obtaining of a -camber is not usable for the rhombic girders, because the coupling nuts are only subjected to pull. Accordingly, no cross forces can be transmitted by means of a coupling nut from the lower boom of an individual part of a rhombic carrier to the lower boom of an adjacent individual part and consequently the diagonal struts engaging the ends of the lower booms of the individual parts and adapted for the transmission of pressure forces from the upper boom to the lower boom, attacking the lower boom ends of the individual parts, completely lose their function and effect.

It is, therefore, one object of the present invention to provide a rhombic girder wherein the upper'boom connection and the lower boom connection of two individual parts can transmit normal and cross forces, and furthermore, wherein the lower boom connection is adjustable in the longitudinal direction, in order to permit a camber of the girder and in which also the upper boom connection can be adjusted to the angular change resulting from the longitudinal change of the lower boom connection, in order to avoid an eccentric force engagement in the two engaging upper boom ends, which force engagement would reduce the loadability of the upper boom.

It is another object of the present invention to provide a rhombic girder, in which from the engaging individual parts of the rhombic girder, one of the parts has a pin at the lower boom end, the pin having an outer face disposed parallel to the axis of the lower boom and the other part has a recess at the lower boom end, which recess is complementary to the outer face and opposite to the pin, the latter being insertable into the recess such, that the cross forces of one lower boom can be transmitted to the other lower boom, and the lo'wer boom is retained in longitudinal direction by clamping or tensioning means, preferably screw bolts, and pressure fast connected with each other by distancing holders of a variable length, preferably pairs of screw nuts disposed on the tensioning means bolts between the end faces of the lower boom.

It is still another object of the present invention to provide a rhombic girder, wherein the latter is designed advantageously such, that the upper boom of the individual parts is held together by tensioning means preferably screw bolts and are held apart from each other in such distance of the end faces by preferably annular distancing holders surrounding the tensioning means, which distancing holders are received in corresponding recesses in the end faces of the upper boom, non-displaceably in the vertical direction, that the upper boom tips about the distance holders and are capable of forming an obtuse angle relative to each other.

It is yet another object of the present invention to provide a rhombic girder, in which a particularly suitable and practical embodiment of a joint connection in the lower boom, consisting of a plurality of individual parts, is provided, or also of another girder type, consisting of a plurality of individual parts, the lower boom connections of which are supposed to transmit normaland crossforces, consisting of an arrangement according to which the joint connection consists of a pin disposed on the lower boom of one of the abutting individual parts, which pin is equipped with parallel horizontal outer faces and consisting further of a guide member equipped with a horizontal slot and provided on the other lower boom, in which slot of the guide member the pin is guided vertically immovable, preferably however horizontally removable, and consisting still further of a tensioning means connecting the lower boom together, preferably screw bolts, and consisting also of a distance holder insertable between end faces of the lower boom, the distance holder being of variable length, which distance holder consists preferably of a pair of screw nuts, which pair of screw nuts is arranged on a thread carrying center part of the tensioning means bolt. This structure makes it possible, that the one part element can :slide from the side in front of the other part element and thereby brings into engagement the pin and the slotted guide member and wherein by simple adjustment of the pair of screw nuts, the distance between the end faces of the lower boom and thereby the camber of the girder can be measured.

It is yet a still further object of the present invention to provide a rhombic girder, wherein the embodiment of this joint connection in the lower boom comprises a structure according to which a pin and the guide member are equipped with ground plates, in which they can be secured at the end faces of the lower boom, preferably by welding. This measure has the appreciable advantage, that upon termination of the individual parts, the base plates can be inserted by means of a templet, into which, on the one hand, the pin and the slotted guide member, respectively, are inserted and which, on the other hand, is set to the screw connection in the upper boom, and the base plates can be welded to the end faces of the lower boom such, that at all individual parts the guide faces on the pins and on the guide member have the same distance from the axis of the screw connection in the upper boom.

With these and other objects in view which will beco-me apparent in the following detailed description, the present invention will be clearly understood in connection with the accompanying drawings, in which:

FIG. 1 is an elevation of a center piece of a rhombic framework girder;

FIG. 2 is an elevation of the lower boom connection of two individual parts of the girder at an enlarged scale;

FIG. 3 is an end view of the right end of the lower boom, shown in FIG. 2;

FIG. 4 is an end view of the left end of the lower boom, shown in FIG. 2;

FIG. 5 is an elevation of the upper boom connection of two individual parts of the girder, at an enlarged scale;

FIG. 6 is an end view of one of the two ends of the upper boom, disclosed in FIG. 5; and

FIG. 7 is an end view of the other of the two ends of the upper boom disclosed in FIG. 5.

Referring now to the drawings, and in particular to FIG. 1, the girder comprises an upper boom 11 and a lower boom 12, as well as, in addition to several vertical and horizontal struts, struts 13, disposed diagonally between the -upper boom and the lower boom, which struts 13 cross each other at their center, so that between the upper boom and the lower boom a so-called rhombic framework is formed, which has between the strut crosses rhomb-shaped framework faces, which are standing on end. The diagonal struts 13 'are arranged and are distributed over the length of the individual parts of the girder such, that a diagonal strut engages directly at each end of the upper boom 11 and of the lower boom 12, respectively. Since the diagonal struts 13 serve the purpose of transmission of pushing and pulling forces from the upper boom to the lower boom, the ends of the booms of the individual parts of the girdens must be connected with each other such, that the boom connections can transmit normal forces effective in the longitudinal direction of the booms, as well as cross-forces effective crosswise to the longitudinal direction of the booms. As can be recognized from FIG. 1, the upper boom ends of the center pieces of the girder are disposed symmetrically and the ends of the lower booms asymmetrically, as will be disclosed below. An end member of the girder would be distinguished from the center member of the girder, shown in F'IG. l, by the fact that at its end of the upper boom, the normal connecting part is replaced by a correspondingly designed support. Simultaneously, on the same side the lower boom connection and the last framework triangle can be deleted.

Referring now again to the drawings, and in particular to FIGS. 2-4, the design of the lower boom connection of two individual parts of the girder are shown in greater detail. The end faces of the lower booms are formed by means of a strong head plate 14, which is welded during the formation of the individual parts of the girder to the ends of the lower boom 12 and to the diagonal strut 13 engaging at said points. lUpon finishing the individual parts, a ground plate 15 is welded to the head plate '14 of one part member, which ground plate 15 carries a horizontal, rectangular pin 16 with an upper and a lower effective outer face 1 (FIG. 4) and a guide member y17 is welded to the head plate 14 of the other individual part, which guide member 17 is equipped with a horizontal, laterally open slot and in this manner has likewise an upper and a lower horizontally effective outer face 1a (FIG. 3). D-uring assembly of the two individu-al parts of the girder, the pin 16 can be inserted in the longitudinal direction and also from the side into the slotted guide member 17 and lits complementarily into the guide member 17 so that cross-forces can be transmitted from one end of the lower boom to the other end of the boom. As can be ascertained from FIG. 2, each individual part of the girder has at one end of the lower boom a pin 16 and on the other end of the lower boom, a guide member 17. FIGS. 3 and 4 show that a corresponding bore 3 i-s provided in the head plate 14 on both sides of the pin 16 and of the guide member 17, respectively, through which bore 3 during the assembly of the individual parts of the girder a screw bolt 2 is extended. Between the head plates 14 are disposed two nuts 5 and 6, screwed to the screw bolts 2, and against which nuts 5 and 6 the headplat'es 14 of the two ends of the lower boom are supported and which are effective as distance holders 'variable as to their length. Furthermore, a nut 4 is screwed on the screw bolt 2, by means of which nut 4, the two ends of the lower boom are pulled ltogether. By means of the screw bolt 2 and the nut 4, during a loading of the individual parts of the girder, the pulling forces are transmitted from one lower boom to the other lower boom. By adjustment of the nuts 5 and 6 and simultaneously tightening of the nut 4, the distance between the two head plates 14 can be reduced in order to camber the two individual parts connected together for a desired amount, that means, in order to form the line formed by the upper booms cambered in upward direction, so that when the girder composed of the individual parts is used as a supporting carrier, for instance, for the manufacture of bridges or other heavy concrete structures and which bends through under the load of the struct-ure material elastically downwardly, a plane structural work bottom view is obtained. By releasing the nut 4, the individual parts can then later be lowered again, in order to take them out easier from the boarding structure.

Within the framework of the present invention, the lower boom connection, that means, the pin and the guide member can @be designed, as a matter of course, also in different forms.

Referring now again to the drawings and in particular to FIGS. 5 and 6, a particularly advantageous embodiment of the upper boom connection of two individual parts of the -girder is disclosed. The end face of the upper boom of each individual part is formed by a head plate 7, which is welded to the upper boom 11 and to the engaging diagonal strut 13. The head plates 7 are equipped with two bores 18, through which during the assembly of individual parts two thread bolts 8 extend, on the ends of which nuts 10 are screwed on. Concentrically with the bores 18, the head plates 7 are equipped with round recesses 18a such, that during assembly of the individual parts in two oppositely disposed recesses a corresponding round distancing member 9 is inserted, which is equipped with a centrally disposed bore, through which the threaded bolts 8 can extend. The thickness of the distancing members 9 is measured such, that the head plates 7 upon tightening of the nuts 10 are disposed at a short distance from each other. Suitably, the ground faces of the recesses and correspondingly the end faces of the dis- Atance holder members are slightly ball shaped. The effect of the distance holders 9 is as follows. Due to the longitudinal adjustability of the lower boom connection, a slight angular variation of the upper boom connection results. If the head plates 7 of the upper boom abut each other obtusely, if the girder cambers, the pressure forces occurring in the upper boom connection would be transmitted only within the range of the lower edge of the head plates 7 as a consequence, this would cause the upper boom to be subjected to an eccentric force attack, whereby its loadability would be reduced. By the distance holding members 9 in the upper boom connection, as disclosed in FIGS. 5 and 6, this occurrence is prevented because without being concerned with a slight angular variation of the upper boom connection, the pressure forces |by the distance holder member 9 are transmitted merely centrically from one upper boom to the other upper boom. Furthermore, if within the range of the joint connection a support is provided and thereby at the joint connection negative bending moments result, which attempt to pull apart the two ends of the upper boom, cross-forces are safely transmitted from one upper boom to the other upper boom by means of the distancing holder members 9 and, thereby, the disadvantages is avoided that the threaded bolts must transmit these cross forces, for which purpose they are not dimensioned normally `and are not in a position to perform.

FIG. 1 shows that the upper boom connections at both ends of the upper boom of each girder part are equally formed. In order that in all individual parts of the girder, the pin 16 and the guide member 17, respectively, have at the end of the lower boom an equal distance of the axis of the screw connection on the end of the upper boom and, thereby, during assembly of a girder from a plurality of individual parts no complications occur, the welding of the head plate 14 to the ground plate 15 with the pin 16 and to the guide member 17, respectively, takes place and in the simplest and safest manner by means of a templet, one end of which is inserted for instance, in the bores 18 of the upper boom head plates 7 and, on the other end of which the pin 16 and the guide member 17 are properly secured.

While I have disclosed one embodiment of the present invention, it is to be understood that this embodiment is given by example only and not in a limiting sense.

I claim:

1. A rhombic girder composed of a plurality of individual parts, comprising an upper boom and a lower boom,

a rhombic framework disposed between said upper boom and said lower boom,

each of said booms including a plurality of individual parts abutting each other,

one of said parts of said lower -boom provided at its end with a pin having an outer face extending parallel to the longitudinal axis of said lower boom,

another of said parts of said lower @boom adjacent to said one of said parts provided with a recess disposed opposite said pin and having an outer face disposed complementary to said outer face of said pin, said recess being adapted to receive said pin, so that cross-forces of one of said lower booms are transmitted to another of said lower booms,

clamping means holding together said lower booms in the longitudinal direction, and

distancing holders of variable length connecting toy gether pressure-fast said lower booms.

2. The rhombic girder, as set forth in claim 1, wherein said clamping means comprises screw bolts.

3. The rhombic girder, as set forth in claim 1, wherein said distancing holders comprises pairs of screw nuts disposed on said clamping means ybetween opposite and facing end faces of said lower booms.

4. The rhombic girder, as set forth n claim 1, which includes l further clamping means holding together said upper booms of said individual parts,

annular `distancing means surrounding said clamping means holding said upper booms of said individual parts in such distance between the respective end faces of the latter, that said upper booms are capable of tipping about said distancing holders and capable of forming an obtuse angle relative to each other, .and

said end faces of said upper booms having recesses receiving said distancing holders immovably in the vertical direction.

5. The rhombic girder, as set forth claim 4, wherein said further clamping means comprises screw bolts.

6. In the rhombic girder, as set forth in claim 1,

a joint connection comprising said pin having parallel horizontal outer faces and secured to said one of said lower booms of said one of said Iabutting individual parts,

a -guide member having a horizontal slot and secured to the other of said lower booms, said pin being guided vertically immovably, but horizontally regiovably in said horizontal slot of said guide memsaid clamping means connecting said lower booms, and

said distancing holder of variable length insertable between each pair of oppositely disposed end faces of said lower booms and consisting of Ia pair of screw nuts, the latter being disposed on a threaded center portion of said clamping means.

7. The ljoint connection, as set forth in claim 6, wherein said pin and said guide member have each a ground plate, and

means for securing said ground plates and thereby said pin and said guide member, respectively, to the corresponding of said end faces of said lower booms.

References Cited UNITED STATES PATENTS 2,308,565 1/1943 Mitchell 52-693 (Other references on following page) UNITED STATES PATENTS FOREIGN PATENTS 2,403,338 7/1946 Butler 10S-64 769,453 3/1957 Great Britain. 2,565,065 s/1951 Chakeres 287-2092 2,594,609 11/1954 Trafford 108 564 FRANCIS K- ZUGEL, Primary Examiner- 2,905,284 9/1959 Hirrzrl 52-645 5 2,985,264 5/1961 Leonard 522-645 US C1' XR' 3,058,132 10/1962 Hedstrom 287-2092 52-645; 287-2092 3,062,340 11/1962 Hunnebeck 52-655

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