US3517474A - Flanged structural assembly - Google Patents

Description

June 30, 1970 A. LANTERN IER 3,517,474

FLANGED STRUCTURAL ASSEMBLY .Filed April 24, 1968 United States Patent 3,517,474 FLANGED STRUCTURAL ASSEMBLY Andre Lanternier, Paris, France, assignor to De Wendel & Cie Societe Anonyme, Paris, France, a company of France Filed Apr. 24, 1968, Ser. No. 723,654 Claims priority, application France, June 16, 1967,

Int. (:1. 1504c 3/32 US. Cl. 52-732 2 Claims ABSTRACT OF THE DISCLOSURE This invention relates to flanged structural members such as girders.

There are already known girders with a core formed by a lattice of oblique tubular pieces forming Vs alternately upright and reversed and with flanges whose extremities are folded toward the core of the girder and then toward the inside of the flange itself along said core, said flanges assuming then the general shape of a V and being possibly hollow.

The mechanical behaviour of such cores is inferior in most cases to that of solid cores. Besides, the fact that the extremity of the flanges is folded in a V toward the core of the girder reduces the moment of inertia of the flange itself.

However the total moment of inertia of such a girder is equal to the sum of the moment of inertia of its flange and the product of the cross section of the metal sheet by the distance between the centre of gravity of the flange and the centre of gravity of the girder itself.

This may be expressed as follows:

where I=moment of inertia of the girder assembly; i moment of inertia of the flanges; S=the cross section of the beam; and D=distance between the center of gravity of the flanges and that of the girders.

Under these conditions and from the point of view of the modulus of inertia, a V shape for these flanges, is in most cases of utilization, inferior from the mechanical behaviour point of view to a rectangular or square shape.

There are also known beams whose flanges each form two bends and which when folded upon themselves towards the inside of the flange form two tubes.

However in girders of this type made heretofore, the inner walls of the tubes forming the flanges were not in contact with the core.

It is also known to manufacture according to previous technique cores which are undulated along their entire surface, said undulations assuming curved or pointed shapes in V or U etc. Now the stiffening of the core with successive deformations along its entire length has the disadvantage of making it considerably heavier due to the fact that the length of the evoluted core is then greater in linear meters per girder than when the deformations stiffening the core are only made from place to place and not one "ice after the other and this regardless of the shape of said deformations.

Besides, in accordance with previous technique, such deformations are often associated to wings having the general shape of a very flat U, that is to say whose edges are folded on themselves without coming into contact with the back of the upper side of the wing. Consequently, the folded parts of the flange form lodgings in which air can circulate and which must be painted to avoid rusting. Now, the deformations used heretofore to reduce the core render extremely diflicult access to the inside of these lodgings to paint them. From this point of view it thus appears preferable to use with such techniques of stiffening tubular flanges in which the tubes 'are totally closed. In this latter case, the oxygen of the air contained inside these tubes is on the one hand partially destroyed by the heat of the welding and on the other hand corrodes only slightly the walls of the tube this corrosion is strongly limited and much less than the total corrosion which occurs with use in the previously mentioned girders.

The present invention thus provides girders with tubular wings or flanges and with a planar core or one stiffened by various deformations, girders whose wings are folded on themselves, characterized by the fact that this folding is carried out in such a way that the cross section of said wings be rectangular or trapezoidal and that the two folded sections converge after a second bending toward the inside of the wing until contact with the back of the upper side of the wing, the core being welded to the two folded sections and preferably along the bend.

The invention is also concerned with a girder whose resistance is increased by stiffening the core through alternate deformations, characterized by the fact that these deformations are discontinuous and do not occupy the entire height of the core in such a way that there remains in the general plane of said core small metal tongues which become lodged between the folds of the flanges and are welded thereto.

Owing to the two previously mentioned characteristics, the majority of the disadvantages noted above with respect to prior art girders are eliminted. On the one hand, the use of completely closed tubes eliminates as indicated above the increased danger of corrosion during use.

On the other hand, the rectangular cross section of the flanges increases as evident from the above given formula the total moment of inertia of the girder relative to that of girders made from the same materials but whose cross section is in the shape of a V as above described in the prior art.

Besides, and for an equal amount of material, the fact that the deformations of the core intended to stiffen it are discontinuous and not juxtaposed diminishes considerably the weight per volume of the girder.

Finally, the fact that there rest above and below perpendicular tongues which do not follow tracing of the deformations and welded to the folds of the flange and bearing possibly against the back of the upper side of the girder eliminates possible problems of welding, which welding can be continuous while in the prior art arrangement with continuous deformations of the core such welding could only be made by spots, which left between the welding spots the possibility of there occurring permanent corrosion.

Other characteristics and features of the invention will appear from a reading of the following description which is given by way of non-limiting example and with the aid of the accompanying drawing in which there can be seen:

FIG. 1 is a perspective view of a girder according to the invention.

FIG. 2 is a view of a girder according to the invention with a profiled core in broken away section.

FIG. 3 is a view taken along line x-x of the support of awing or flange along a V-shaped deformation of the core.

FIG. 4 is a view of the cross section of a sheet for forming the V-shaped core.

There is seen in FIG. 1 the two wings or tubular flanges referenced A and B having a'cross section in a generally rectangular or trapezoidal shape which may be cold drawn along all or part of their surface and whose edges are rounded. The two flanges 1 and 2 have folded edges: 3, 4, 5 and 6 bent at an obtuse angle and converge in the middle of planar surfaces 7 and 8.

These two tubular profiles forming wings or flanges A and B are connected by a flat core 9 which in the example given is welded along lines 10 and 11 through folds 3, 4 on the one hand and 5, 6 on the other hand. The core 9 comes into contact with surfaces 7 and 8.

The new industrial advantages contributed by this type of girder are numerous.

The cold forming process causes first a very substantial increase in the elastic limit and permits consequently the support of greater stresses by smaller thicknesses of girder; it has been shown that in these latter breakage was no longer to be feared.

Additionally the manufacture by continuous cold forming of the tubular members and the continuous welding reduces considerably the labour costs.

Owing to their construction, the only limitations in the length of these girders are placed thereon by the need to transport the same and not by their dimensions or mechanical characteristics. The facilities of transportation are additionally increased because of the decrease in weight for equal mechanical performance.

From the standpoint of the resistance of the materials themselves, the support of central core 9 possibly reinforced by stifl eners along outer faces 7 and 8 avoid that local deformations due to loads become cumulative with deformations of the assembly. The resistance to cutting efforts is greatly increased. Additionally the weight gain of the order of 50% diminishes considerably the cost of material of said girders.

By using appropriate stilfeners there is increased considerably the effort giving rise to skin drying upon compression as well as upon flexion.

There is seen in FIG. 2 a girder according to the invention whose core 9 has been preferably cold shaped in order to have the profile of a broken plane from place to place in the form of a V, for example at 12 and 13.

Such a core is obtained (FIG. 4) from a sheet 14 by folding along lines '15, 16, -17. There will be provided however, preferably by matricing or any other process and thanks to notches of judicious shaped tongues 18, 19, 20, and 21 which are seen in FIG. 2.

These tongues permit to continue the welding in the core along axis y-y', welding which would have been largely interrupted from place to place owing to the V deformations.

Referring then to FIG. 3 there can be seen how the flange A bears by its face 1 on the V 13, formed by the core. From then on an eccentric stress (arrow W) is easily supported.

What is claimed is:

1. Structural assembly comprising at least one elongated member with a main portion arranged in a single plane and having side flanges with folded edges extending therefrom in a plane parallel to said first-mentioned plane, said edges having their convergent extremities bent toward the middle of the upper surface of said member at an angle defining a channel between said extremities; a core member arranged in a plane perpendicular to said first-mentioned plane, the lower end of said member being received by said channel and a weld between each of said extremities and said core member, said core being positioned so as to bear on the back of an upper face of one of said flanges, thereby to increase the resistance thereof to cutting stresses.

2. Structural assembly comprising at least one elongated member with a main portion arranged in a single plane and having side flanges with folded edges extending therefrom in a plane parallel to said first-mentioned plane, said edges having their convergent extremities bent toward the middle of the upper surface of said member at an angle defining a channel between said extremities; a core member arranged in a plane perpendicular to said first-mentioned plane, the lower end of said member being received by said channel and a weld between each of said extremities and said core member, said core having alternate deformations and small metal tongues fitting between ends of said flange and welded thereto.

References Cited UNITED STATES PATENTS 426,558 4/ 1890 Dithridge 52729 X 1,488,095 3/ 1924 Connell 52-73l X 3,167,851 2/ 196 5 Cowan 52-731 X 3,342,007 9/1967 Merson 52-729 FOREIGN PATENTS 69,106 1951 Netherlands. 414,118 12/1966 Switzerland.

PRICE C. FAW, JR., Primary Examiner US. Cl. X.R. .52729

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