NZ219278A - Girder with corrugated, rippled web - Google Patents

Description

Peg.19(1) F*««: S1-' " * ^ P:.or!'v Date, , ^ r j ,„.u;e Spi=''?«-*von Filed: :**• • • * 2 1 >■ n3 (each) applicant.

PATENTS ACT 195 3 Insert nu-.ber Number: of crcvi sicr.i I Specifications) r, , [is* (if any) 3id Date: d3te(s) of filing; IW 'fOpplbw^. otherwise leave V\^> blank* COMPLETE SPECIFICATION N^. . .

Insert Title PLATE WEB GIRDER of Invention. -insert full naie, I/WE FRANCISZEK WARCZAK, of 66A Lime Street, 11 street address and nationality of Cabramatta, New South Wales, Commonwealth of Australia, an Australian Citizen hereby declare the invention for which I/we pray that a patent nay be granted to me/us and the method by which it is to be performed, to be particularly described in and by the following statement:— Indicate if following page is numbered M(a)1 l.'O.nfi ^ 2 1 The present invention relates to plate web girders which conventionally comprise a pair of elongate parallel spaced apart flanges and an elongate web extending therebetween.

It is well established that, when a bending moment is imposed upon such plate web girders a large proportion of the resultant bending stress is carried by the flanges and that the web must be sufficiently stiff to hold the flanges in spaced apart parallel relationship. That is to 10 say, the integrity of the girder depends inter alia, on the web not buckling.

It is known to corrugate the web to increase its stiffness to thereby provide a girder with an improved increased strength to weight ratio. However, it has been found that large corrugated webs are none the less prone to buckling because due to the size of the corrugations, the web acts locally like a plane web and as a result local buckling may occur.

It is an object of the present invention to provide 20 an improved girder.

Accordingly, the present invention consists in a girder comprising a corrugated web as defined herein, fixedly interposed between two flanges, characterised in that said web is rippled, the ripples extending in a direction substantially parallel to the direction of extension of the corrugations.

A preferred embodiment of the present invention will now be described by way of example only, with reference "V ^ » j -—j w to the accompanying drawings in which; Figure 1 is a sectional plan view of a girder according to the invention; and Figure 2 is an enlarged sectional plan view showing an encircled portion of the girder in figure 1.

Referring to the drawings, a girder 1 is shown which comprises a corrugated web 2 fixedly interposed between two flanges 3, only the lower one of which is shown for clarity.

As is best shown in figure 2 the corrugated web 2 is rlppled.

Preferably, the thickness "t" of the web material is in the range; 2t<: a£ 6t where "a" is the amplitude of the ripples.

Additionally, the wave length "b" of the ripples should be in the range; 3tZ b t 6t It has been found that a suitable way of producing 20 the rippled corrugated plate is to firstly pass a flat plate through a press which stamps the ripples, a few at a time, into the plate using a pair of dies fashioned in the manner of a pair of intermeshing racks. The rippled un-corrugated sheet is then passed between a pair of parallel rollers, each having axially extending, radially projecting, intermeshing protruberances which effect the bending of the rippled plate into its final corrugated form. The rippled corrugated web is then welded to the flanges in conventional manner.

Preferably, the wave length "L" of the corrugations is in the range; 2A t L t 4A where "A" is the amplitude of the corrugations.

In the preferred embodiment the corrugations are defined by a series of substantially semi-circular, opposed curve portions. However, a corrugated web is defined herein to comprise a web being corrugated in any manner so as to have crests and troughs and is not restricted to include only webs having sinusoidal corrugations.

Similarly the ripples may have any of the above-entioned forms.

For preference the girders are fabricated from steel however, they may be fabricated from any metal or from any suitable plastic.

Claims (6)

2!5278
1. A girder comprisir.g a corrugated web as defined herein, fixedly interposed between two flanges, the web being rippled, the ripples extending in a direction substantially parallel to the direction o£ extension of the corrugations wherein the wave length "b" of the ripples is in the range: 3t ^ b $ 51. where "z" is the thickness of the web material. corrugated form, and welding the sides of the ripples and corrugated plate to the flanges. - 5 - - 0 NOV 1989' .fV" -iv/
2. 2. A gircer according to Claim 1 wherein the amplitude ; "a" of the ripples is in the range: j 2t i a ^ 6t. f i- i i
3. 3. A circer according co either preceding Claim wherein f the wavelength "L" of the corrugations is in the f range: - 2A ^ L ^ 4A. | where "A" is the amplitude of the corrugations. I
4. 4. A girder according to any one of the preceding Claims T *;fabricated from metal. ;;1;2;
5. 5. A girder substantially as herein described with \;i reference to figures 1 and 2 of the accompanying 'f drawings. • \;i *
6. 6. A method of producing a girder according to any one l of the preceding clairrs, comprising the steps of t I stamoing the defined riDoles into a flat Dlate, i- I-" passing the rippled flat plate between parallel rollers adapted to shape the flat plate into O 1 c. ' A method according to Claim 6, wherein the stamping of the ripples is done using a pair of dies in the form of a pair of intermeshing racks. A method according to Claim 6 or 7, wherein the corrugations are formed by passage of the plate between a pair of rollers, each having axially extendir.g racially projecting, intermeshing protuberances. A method of producing a girder, substantially as described herein. J. D. 2. CO.