AU550570B2 - Purlin - Google Patents

Abstract

Cold-rolled steel purlins have parallel oppositely directed flanges, one major (3) and one minor (1) with a flat outer fixing surface, terminal inturned lip (4, 9) and longitudinal strenghthening groove (8, 13) nearer the inner edge where a central connecting web (2) joints at 90 DEG (14, 16) but is so angled in central regions that a notional plane at right-angles to each flange flat surface longitudinal midline passes through the web and the other flange flat surface. The minor flange outer contour matches the major flange inner contour. The flange lips (4, 9) are angled at least in part at less than 90 DEG . The purlin has good mechanical properties, and can be nested in pairs (with minor flanges inside major flanges) or sacked in the same sense either as individuals or as nested pairs.

Description

EGULATION 11(1)

~COMMONWEALTH OF-AUSTR ALIA

THE PATENTS ACT 1952-196:9

CONVENTION APPLICATION' FOR A 'PATEi4T 55057 XUwe, AYRSHIRE METAL P .RODUCTS LIMITED LO-G A1U-STA AN

M~AY 198

Irvine-, Ayrshire, Scotl-and

hereby apply for the grant of a Patent for an inventjon

1~ 04. e~titled: 4. 0 00. 0 IMPROVEMENTS IN PURLINS 00 0 0. 0 0 00 0

4 00 fh is aescribed in the accompanying complete specification., 0 0~ 04.' 4.0

0 0 4.4 Thsapplication is a, Convention application and is based on the 0 00 0.0 4 0 application(s) nur~be~ed: 8135267

for a patent or similar protection made in Great Britain 00 4 .04.

0 0 04.

.00 'UPtTL-D AND~ Ati-Nt%r, 0 44 00

on, 23 November 1981 0 00 O 0* .44 004. 0 *C))Our address' for service is Messrs. GRIFFITH, HASSEL FRAZER, Patlent 'Attorneys, of 71 York Street, SYDNEY*. New 00 44 0 0 4 0 South Wales 2000, Commonwealth of Australia.

DATED this 30th day of April Jo82

.4

AYRSHIRE METAL PRODUCTS LIMITED By their Patent Attorney 3MAY 1982, PATENT OFr-rE

of GRIFFITH, HASSEL &.FRAZER Fellows, Institute ,of :Patent kttorney, of Australia

,uenzion sBhouU be dhiefl6l.)

COMMONWEALTH OF AUSTRALIA, Patents Act*1952-1960

DECLARATION IN SUPPORT OF A: CONVENTION APPLICATION ISTRUCTIONS FOR A PATENT ORPATENTOF.ADDITION, In nert 14o' if allible Ih support of. the Convention application In sert full nnione(x) of Iapplicant(s), made by (b)._AYR8..IRE L I I I i 1.1.1

In "ert titl invent!nt of for a patenit 'rnd A for an invention entitled in Purlins.... .Improvements

v Insert full .of declarn mu~ne~s) T/ed) SECRETARY of' care of and on behbalf ~fARHR EAJPRODUCTSLIIE el Insert add declarei of~00 a

00o.

do solemnly and sincerely declare as follows:

(or, in the case of an (tpplication by a body corporate) 1. 1 am/Wo -ar ahuthorized by the abovementioned applicant(s) for the pateit/pmte~- ~-adiie to make -this. declaration on its/their behalf. a0 Q 2. The basidc application(s) as defined by Section 141. of the Act was/were made in the following country or, countries on the following date(s) by the following applicant(s). namely:- C) 0 Insert coun tr nII GREAT -BRITAI'i on 23rd November 19q a eo wbkch firmt basic in r a amlication filed. wasby*(h)_ 4.YSHIRE METAL PRODUCTS IMrITED of Insert date basic appli cto iby On eel) Insert full by~(e o 19 of basic applicarit(a

Inserf fu~ll (or wherea personother titan the inventor is the applicant) .of .actual 3. )IEADRW JAE

lnveintor(c)

f *F K y Insert addr of actual i inventor(s) T a a 1

Is/are-.the actual inventor(s) of the invention and the facts upon which the, applicant (s) is/are entitled to make the application are as follows:- Recite man ne I ,which appl e pjiat ar 't assignees aof the I.nvention.... Aerive(s) ti tl~efrom fro theaculnen r. aetual inye

The-basic application(s) referred to in. paragraph .2 of this Declaration wis/were the first'application(s) made in a~ Convention country in. respect of the invention the subjeict. of the application. (b intr~1~ Declared at Av [f.EIA1/ k this twel-nint da' of 4rh 1982 (Note: No atte~tatlrn or other signature ia re- L'A' bw~rnni LA'N 7'

To: The ommnissioner of Patents, Commonwealth of Ailstralia.

Tit e. zri

(12) AUSTRALIAN PATENT ABRIDGMENT (19) AU (11) AU-Bz83198/82

(54) PURL I (71) AYRSHIRE METAL PRODUCTS LIMITED (21) 83198/82 550570 (22) 3.5.82 (24) 23.11.81 (31) 8135267 (32) 23.11.81 (33) GB (43) 2.6.83 (44) 27.3. 86 (51)3 E04C 3/07 (72) JAMES ERIE ANDREWS (74) GH (56) 54467/65 81.4, 81.3, 78.1

(57) C1 a imi 1. A cold-rolled szee1 purlin of the type

possessing a central web with two oppositely-directed

generally parallel flanges each with a flat outer

fixing surface and inturned lips, in which (a)

a-plane vertical to the midline of either flange

fla £urf~aepasses through thek-Gt1-e- flange .P-at-

-ita-&e-E- the web meets each flange at an

angle of substantially 900 each flange is

deformed to provide a strengthening groove along

the flange between the midline of the flange

and the web one flange is a Dninor flange and

the other a major flange, the outer contour of the

minor flange and adjacent web portion substantially

matching the inner contour of the major flange

and adjacent web portion and each inturned

=115(32 )/22

1. i

Figure 2 shows other nodes of stacking. Since

as described above, the inner contour L C J G D is

over nost of its length (not the extreme end) the spmp Ap

Slange lip is anigled with respect to its flange to

allow two identical purlins to be placed together

with th eminor flange of one inside the major

flange of the other, with the substantially matching

flange contours face to face to provide a stably

nested pair of purlins for transport, storage or

assembly.

3-

==115(32)/23

Stacking as at Figure 3 involves the end

of each flange lip 17 or 18 nesting on the flat face

of the neighbouring flange, because of the rather larger ~i:.c~n~Rf c 7 n' of Australia

AForm 1 SAtT1-952 .'PT ET 1 9735

COMPLETE. SPECIFICATION (ORIGINAL) FOR OFFICE USE Class:

int. Cl:

Application Number: 03 ~l~f~r~J made1 rr.xw~er Lodoed:

Cornplete'Spe.-ification='Lodoed: Accepted: 0 Published: Prioriiy: 0

RE late Ait:

TO EE COWPLETED B.Y APPLICANI Name of Appicpnt: AYRSHIRE METAL PRODUCTS LIMITED

A~ddress of A;p' canlt Irvine, Ayrshire, Scotland

James Erie Andrews

Address for Se'v.,ce: GRIFFITH, HASSEL FRAZER 71 YORK STREET SYDNEYt N.SOW. 2000 AUSTRALIA Complete Spe-J~ication for the invention entitled: IMPROVEMENTS IN PURLINS

The following.,stat ementI isja full description p1 this invention, including the best method of performing it known to rne.s: F

*1 *Figure 5a shows the cross-section of a well- known type of purlin. When installed under load, there is a neutral plane or axis, indicating the effenc--.HvP

Title: "Irovements in 'Purlins"

This invention relates to purlins cold-rolled from

-steel strip, and to roof structures incorporating such

purlins.

It is well known to fabricate purlins i.e. lateral

roofing members, by severing from a roll a desired

length of steel strip and passing it through a succession

*of roller pairs. Each roller pair deforms the strip along

S"f its length and. after the successive deformations caused

by the successive roller pairs the desired purlins is

S" 0 obtained having uniform transverse cross-section and

Scorresponding in length to the original severed strip.

A simple and widely used cross-section provides a

flat central web with two flanges,possibly of equal width,

but usually of different widths each at right angles to the web at opposite sides thereof. Such flanges are provided

with outermost lips, bent inwards at right angles to the

flange so as to lie parallel to the web.

Another known .cross-section similarly provides a

central web with two integral flanges at right angles thereto and, if desired inturned lips..In this case, however, the flanges extend from the same side of the web, to provide

a charnnel section, .and the web itself is deformed along its

central region so as to give a substantial strengthening

2

Currently, roofs are made to lower pitches than

hitherto. We have found that a more useful shape for

a low pitched roof is as shown, according to the

:i

ridge of generally trapeoidal cross-section extending

within and along the channel.

We have established that the design of purlins

while being based partly on aesthetic appearance also

involves a compromise between various considerations

for example convenience of manufacture, con-

venicence of storage and transport, convenience of

assembly, and performance under static or dynLmic 9 r

load. 49 9

9: 9 By way of example, a simple prior art purlin

discussed above is easy to roll since only right-angled

bends, obtainable with relatively few roller pairs, are 4 90

9 1 9.9Y involved. The other prior art example, however with .9 9.9

flanges turned the same way, and lips rolled to oppose 9o .99 W one another, needs the trapezoidal web profile to be .99 .94

incorporated. This needs more distortion and more rollers

of more complicated shape.

Another difference, in storage and transport.

convenience, can be seen between the two prior art purlins

discussed above. A notional purlin with flat oppositely-

directed flanges would stack with faces contacting, to

minimise storage space or transport space and to facilitate

bulk handling. Such a purlin as commercially used with

additional lips and differently sized flanges will stack

in a convenient manner. The channel-shaped purlin however, .4t 3

Ni M=Mmffw

'i~li ,s

does.not stack for storage or transport and for these

purposes needs a larger'envelope of space.

During assembly, however, the generally charnnel-

shaped prior art purlin possesses certain advantages

over the prior art purlin with oppositely directed flanges.

This is because the latter tends to "rotate" around its

longitudinal axis since its weight is distributed to

either side of that axis. With a channel-shaped purlin,

there is no maldistribution of weight, with consequently

o o'10 easier assembly techniques e.g. temporary or partial

-*Od fixing until other members are placed and fitted.

This problem of "rotation" persists in the

assembled roof structure. In general, however, the detailed

characteristics of performance under static load (from the roof itself) temporary excess static load from

snow loading) dynamic loading by wind pressure) or

non-uniform loading e.g. during repair or extension are

not predictable. They depend-on performance of the purlin

under torsion, its bending and buckling performance, and

its performance under longitudinal stress. While computer

sinmulation studies can give partial answers it is in this

technology usually more practical to assemble the purlin

at a desired load, support spacing, and position, and

Si

The cai's definfng t nvenltion are as follo

1. A ctld-rolled steel purlin of the type r for these monitorits performance empirically.

The present invention provides purlins

3.lly chanel- with a different type of cross-section, having a novel

and advantageous combination of properties, and with good Ivantages

Lrected flanges. 5 mechanical characteristics in use.

I around its

Ibuted to Purlins according to the present invention

possess mutually parallel flanges extending from the ,ped purlin, 44 eentral web in opposite directions (as in the first consequently 4.4

mentioned example of prior art discussed above) but partial 4

4 44.

tted. with the central web so shaped that the flanges, viewed

from above the purlin overlap least in part (as in the

second example of prior art discussed above). They further in the 4O 4 4

r, the detailed pdssess features of relative dimension and shaping as

4; 4 defined below. load (from 4L 4

44 .d from 44 44 4 4 444 15 The invention consists in a cold-rolled pressure) or 4 4 4

044 steel purlin of the type possessing a central web with tension are two oppositely-directed generally parallel flanges each of the purlin 44 n 40 with a flat outer fixing surface and inturned lips, ormance, and in which: a plane vertical to the midline of either bile computer 20 flange flatsurfaco passes through the other flange flat, it is in this sufae-e-(b)'/ the web meets each flange at an angle of a the purlin substantially 900 each flange is deformed to provide ion, and a strengthening groove along the flange between the midline

ofi >e flange and the web one flange is a minor

flange and the other a major flange, the outer contour of

the mmn.QZ flange and adjacent web portion substantially

c1 I

the web meets each flange at right angles are

themselves joinea by a single angled planar central e tyPe i i N|

1 matching the inner contour of the major flange and adjacent

web portion and each inturned flange lip is angled

with respect to its flange to allow two identical purlins

to be placed together with the minor flange of one inside

the major flange of the other, with the substantially

matching flange contours face-to-face to provide a

stably nested pair of purlins for transport, storage, or

assembly.

We have found that this combination 'of characteristics 0 na

gives an optimum product suitable for a range of roof

pitches, for reasons, set forth in more detail below, 0 0

0so 'o 00 connected with the so-called "neutral plane" of the section.

Because the plane from the midline of each flange

flat surface passes through the other such surface the

purlin does not "rotate" during fixing. It is however 44,

preferred for strength if each such planepasses through 00 4 ,B the other flange at points nearer the web, e.g. between the

web and the groove.

It will be apparent that with this constraint on

the relative flange positions the web must be in some way angled in relation to the flanges. We have found,

however, that a simple plane web departing from each flange

at an angle is not desirable, and that each edge of the web

should be at substantially 900 to the flange, moreover, the

strength thus imparted, given the behaviour under compression

6

4 ~C i~Lira;-l~:t- -i e, imposed by the "overlapping" flange~s should be supplemented by the strengthening groove as defined.*

This can be achieved in different ways. In one, the web leaves the flanges at right angles, and joins Sthese portions by a simple angled plane central portions. In other, the web leaves the flanges at right angles, proceeds inwardly at an angle and joins these angled portions by a central plane portion itself at right angles to the flang flat faces.

edge portions of the web, at right angles

to the flange, can extend for example to a depth equal

to the vertical depth of the inturned lip on that flange.

4

The groove cross-section can be rounded or angled e.g. trapezoidal. If desired additional grooves,

e.g. on the outer side of the flange surface mid-line, can be incorporated, although of course a general~y flat fixing surface -must be preserved at the outer face of the flange.

Since the major flange inner contour and the

minor flange outer contour substantially match, it will be apparent that the right-angled marginal region of-1t1he- -web in the two cases has a different depth, that at the minor flange being less than that at the major flange

'and that correspondingly the grooves should have

different cross-sections, that in the minor flange

being wider and deeper than that in the major flange.

The vertical height of the lips in each case, however,

can be the same or different, depending on whether it is

desired for the lips at one end of a nested pair to end

in a common plane parallel to the flange face, or not.

In any case, small differences in the original strip

width tend to show up as eventual differences in lip

10 height, so that it is valuable if the design is such as

to accommodate these differences.

These flange lips themselves are not simply

at 900 to the flange flat faces since the approximate

Z-shape of the purlin, would then render it impossible

15 to bring two purlins edge to edge together for nesting.

'Optionally, the shape of t-he purlins can be u such that other modes of stacking are also possible.

SOne useful optional characteristic is tc

design the flanges and lips so that purlins can be

stack-d in the same sense with major flanges

adjacent). Clearly, these flanges will not fit closely

one inside the other. Therefore the lips must contact

the outer flange faces (or possibly the outer lip faces)

of the same size flange. This can be readily achieved if

the lips have the same vertical height and rest in each

i. I 8 case upon the outer flange faces. If the major flange :should havo lip has a greater' vcrtical height than the minor flange Lnor flange lip, it will need to rest upon the outer angled lip -t major flange. surface, i.e. the major flanges will need to stack i-: case, however, 5 slightly inside each other, to compensate for this ;4 :i on whether it is difference. r

3ted pair to end i

face, or not. -9 With such stacking, the angled region of the ?iginal strip web imposes a lateral shift of adjacent purlins. Where 2ences in lip the web is of the type where there is a simple angled sign is such as plane joining the marginal web regions, this still permits V 0s

a high proportion of face-to-face web contact; where the

web is of more complex shape, the detailed dimensions and. anot simply proportions of-the pmrlin should preferably allow at least i C)~j I ie approximate two spaced web-to-web contact regions in the stack. I

2 it impossible i Examples of this are described more fully below. ier for nesting.

A major desirable chara.,eristic is to dimension -lins can be the flanges and lips so that it is possible to stack the -so possible. nested pair as described above. A nested pair, as distinct

from a singP purlin, is symmetrical. In such cases, it ic is to 20 is sometimes desirable that the major flange lip vertical ins can be height is greater than the minor flange lip vertical height, or flanges to an.extent such that they terminate in a common plane ot fit closely parallel to the flange flat face; this facilitates subsequent must contact stacking of such pairs. As noted above, however, the Duter lip faces) 25 individual differences in lip height arising from differences lily achie-ved if in strip width from batch to batch can be accommodated without id rest in each

83 198/2

CJ ,3

16 V4I 12I3 r detracting from this stackability. jor flange ainor flange 1~ Although the invention is primarily directed led lip ;I: towards purlins as described above, optionally stackable stack :li :~d in the additional modes defined, it also extends to a )r this :a roof structure incorporating such purlins.

The invention will be further described with )n of the reference to the accompanying drawings, in which:- Lins. Where ?le angled O I:~ Figure 1 shows and end view of a purlin still permits CIC according to the invention in stacking relationship with where the C C:

Cr another identical purlin, limensions and

allow at least C0

Figure 2 shows a partial end view of a purlin stack. as in Figure 1 paired with an identical purlin, and 310w. also such pairs ofl purlins in a further stacking CB C

relationship, to dimension to stack the CPI C Figure 3 shows an end view of another purlin r, as distinct according to the invention, in a stacking relationship h cases, it as in Figure 1, lip vertical vertical height, Figure 4 shows the paired and stack ed purlins nmon plane of Figure 3. Ltates subsequent rer, the Figures 5a to 5d show diagrammatically the neutral from differences plane of a prior art purlin, and the positioning of such .ommodated without

83 198/2

iS Hi a purlin on a roof, in comparison with the neutral plane of purlins according to the invention.

irily directed

;ionally stackable The purlin of Figure 1 has a minor flange 1

3o extends to a extending from A to B, a .eb 2 extending from B to C and

ins. 5 a major flange 3 extending from 0 to D generally parallel to flange 1. It is of a general Z-cross-section, so that

lescribed with each flange has an outer surface and an inner surface in

Sin which:- relation to the Z-shape.

a purlin Flange I is further divided into lip 4 from A to

relationship with ,10 E and flat face 5 from E to B. Lip 4 has an outermost

portion 6, at 900 to flat face 5 and an inner lip portion

7 at 1355 thereto as shown. The vertical distance from

Lew of a purlin flat face 5 outer surface and the end of lip 4 at A is HI.

L purlin, and Point F is halfway between E and B. Between F and B is a

stacking 15 swaged groove 8.

SFlange 2 is-similarly divided into lip 9 from D to

mother purlin G. and flat face 10 from G to C. Lip 9 has outermost portion

.ng relationship 11, at 1150 to flat face 10, and inner lip portion 12 at

135 thereto. The vertical distance from flat face 10 outer

surface to the end of lip 9 at D is H2 Point J is halfway

tacked purlins between C and G. Between J and B is a swaged groove 13.

Web 3 extends from B to C as a connecting o bically the neutral portion 14 from B to K, at 90 -to flat face 5, point B also

3itioning of such being .t distance HI from the flat face 5 (ii) a central

1 1 portion 15 from K to L and (iii) a connecting portion

16 from L to C; at 9°O to flat face 10, point L also

being at distance H 2 from flat face

A notional line from F at right angles to flat

face 5 passes between C and G, and similarly a

notional line at right angles to flat face 10, from

point j1 passes between B and E.

H2 is greater than H1 by an amount approximately equal to the thickness of the material. Distance CG is

greater than distance EB by at least a thickness of

material. The inner contour from J-to L is the same

as the outer contour from K to F. Two such purlins can

be stacked, as shown in Figure 1. Flat surfaces 10 and 1

come to rest at a distance H3 (slightly less than

H2 apart, because the angled outermost lip portion

11 permits the next purlin flange 3' to fit to a minor 4 and stabilising extent within flange 3. Similarly,

flange 1' will fit over flange 1, again with the flat

surfaces 5 and 5' a distance H3 apart since outermost 0

portion 6' is at 900 to 5' and rides on portion 4 4 slightly differently from portion 11 riding on 12'. :f 0 P I At this stage, there is good face-to-face contact

of web central-portions 15, 15'. The portions 16, 16'

or 14, 14' or grooves 13, 13' and 8, 8' do not abut

or destroy stable stacking behaviour.

12

-I -i ~~l~iii~pi~a~a

==115(32)/22

Figure 2 shows other modes of stacking. Since

as described above, the inner contour L C J G D is

over most of its length (not the extreme end) the same as

outer contour K B F E A; and since moreover groove 8

outer flange contour is the same as groove 13 inner

flange face contour, with complementary spacing from

the points B and C respectively, good nesting in pairs as

shown in Figure 2 is achieved.

Such pairs of purlins are symmetrical and

accordingly only one end of the section is shown, for

clarity of illustration. Such summetrical pairs, especially

when E is less than H 2 to give a termination of paired

flanges at the same level, can be easily stacked in a C

stable fashion, also as shown in Figure 2. Ce

BC Figures 3 and 4 show how a more complex shape of C, C I- I purlin, still possessing swaged grooves in the flat faces,

and still having 900 angled connecting portions at the CI,

ends of the web (in relation to those flat faces) can

also be designed to stack in several modes.

20 In this case, flange lips 17 and 18 genceally

resemble flange lips 4 and 9 in Figure 1, except that 1 they project to the same vertical height H 4 from their S respective flat face. Moreover, the central web has a

.i major portion 19 at right-angles to these flange flat

faces.

Stacking as at Figure 3 involves the end.

Sof each flange lip 17 or 18 ne.ting on the flat face

of the neighbouring flange, because of the rather larger

displacement to one side necessitated by the shape of

the web. However, since they both have the same vertical

height H. the purlins are stacked parallel. As shown, the

angled portions 20, 21 of the web are in minor but

adequate contact at 22 and 23, contact area 22 being

slightly larger due to the small size differences between

the major and minor flanges as in Figure 1. Thus, even

for this more elaborate shape stable stacking can be

achieved.

Figure 4 shows that purlins of Figure 3 can be

nested in pairs (as chieved in Figure 2 for the purlins

.5 of Figure There is a minor flange 24 nesting within

a major flange 25, by virtue of the matching of the

respective outer and inner contours. The size of gap

26 at the end is optional, but should be adequate to

permit the minor flange to slide in past the angle at

27. However, the good matching of groove contour is

adequate to ensure good nesting.

9r9C 9i L C cs Figure 4 also shows how the symmetrical pairs

can be stacked. In this case the webs have two

symmetrical patches of face-to-face contact (one not shown)

e.g. at 28 on the central web region. Again this provides

stable stacking behaviour.

<tci, ~cv.'9rai,.5 C

Figure 5a shows the cross-section of a well- known type of purlin. When installed under load, there

is a neutral plane or axis, indicating the effective

resultant of forces and depending upon the geometry

of the section.

This neutral plane passes at an angle through

the web of the purlin. The size of this angle depends

predominantly on the relative dimensions a and b, as

shown in Figure 5b, these being'the flange width and the web height respectively. In theory, a given a/b

ratio is optinum for a roof of a given pitch 8, since

the neutral plane is then vertical. r

c

Such profiles as shown in Figures 5a and

cannot however usefully be made over a wide range of

a to b. Other physical characteristics such as torsion,

buckling and bowing resistance are also potentially

"o affected by this ratio. Also, if a is too small on an

absolute basis, it becomes difficult in site conditions

to ensure fixing of cladding panels to these flanges. Typically the edges of such panels meet along a flange,

and a narrow flange cannot accommodate casual

differences of panel dimension or alignment over a long

run of purlins. The height dimension b can be altered to

some extent, so as to be used on a lower pitched roof,

but then the total weight of purlin,. and its overall size and cost in'increased.

E r

Currently, roofs are made to lower pitches than

hitherto. We have found that a more useful shape for

a low pitched roof is as shown, according to the

invention, ii Figures 5c and 5d. The neutral plane is at

a very small angle to the vertical, or even parzallel

to the vertical web portion of Figure 5d. Moreover,

the flange is wider for a given angle of roof, so as to

provide for easier fixing over a long run. Purlins

as shown according to the invention, in Figures 5c and

are usable with little variation over a wider range

of roof types than those of Figures 5a and

4

V~

V 44

44 4 4 4

44 4 4 4 4 4*

44 4 4 4 4 *4

4 44 44 4 4 4.4

4 44

44 .4 .4 4 4

16

I -i pitches than I1 shape fLor to the al plane is at npazallel Moreover, ooaf, so as to Purlins gures 5c and wider range

1 cdhts defining the invention Tx a ass follo

1. A ctid-rolled steel purlin of the type

possessing a central web with two oppositely-directed

generally parallel flanges each with a flat outer

fixing surface and inturned lips, in which (a)

a plane vertical to the midline of either flange other flat surfaco passes through the uter flange flat-

-surasee-(b) the web meets each flange at an

angle of substantially 900 each flange is

deformed, to provide a strengthening groove along

S. the flange between the midline of the flange

and the web one flange is a minor flange and

the other a major flange, the outer contour of the

minor flange and adjacent web portion substantially StmTatching the inner contour of the major flange

and adjacent web portion and each inturned

flange lip is angled with respect to its flange to

S"allow two identical purlins to be placed together

with the minor flange of one inside the major

flange of the other, with the substantially matching

flange contours face to face to provide a stably

nested pair of purlins for transport, storage or

assembly.

2. A cold-rolled steel purlin as claimed in

claim 1 in which the web portions defined where

1j "W the web meets each flange at right angles are themselves joinea by a single angled planar central portion.

3. A cold-rolled steel purlin as claimed in

claim 1 in which the web portions defined where

the web meets each flange at right-angles are

themselves joined first by angled portions and

then by a central plane portion itself at right

angles to the flange flat faces. C o

4. A cold-rolled steel ourlin as claimed in

claim 1, 2 or 3 in which the web portions defined

where the web meets each flange at right angles o extend in each case for a depth equal to the

vertical depth of the inturned lips on the said

flange.

o.

A cold-rolled steel purlin as claimed in

ilaim 1, 2 or 3 in which the flange lips (17,18) have

the same vertical height whereby two such purlins

S" can be stacked (Fi-gue in the same sense with

a lip of each purlin in each case contacting

the outer flange surface of the other purlin.

6. A cold-rolled steel purlin as claimed in

U,. 0 V claim 1, 2 or 3 in which the flange lips have different vertical heights, whereby two such purlins can be stacked in the same sense with a lip of at least one purlin contacting an outer surface of an angled lip of the other purlin.

7. A cold-rolled steel purlin as claimed in

claim 1,2 or 3 in which the flange and lip shape

and dimensions are such that a nested pair of

purlins, assembled with the minor flange of each

within the major flange of the other, can be

stacked with another such pair, in the same sense

with a lip or the lips of each contacting flange

pair itself contacting the outer flange surface of

an adjacent flange pair.

8. A cold-rolled steel purlin as claimed in

any one preceding claim in which the groove

cross-section is rounded.

9. A cold-rolled steel purlin as claimed in

any of claims 1 to 7 in which the groove cross-

section is trapezoidal.

A cold-rolled steel purlin as claimed in

any one preceding claim in which possesses an

additional groove on the outer side of each flange

\iMMIM11gWIM m m a surf ace Liidline.

11. A roof-structure which incorporates purlins

as claimed in any one preceding claim

12. A cold- rolled steel purlin substantially

as described with reference to Figures 1 and 2 of the

accompanying drawings.

13. A cold-rolled steel purlin substantially

as described with reference to Figures 3 and 4 of the 66 6 6 60 accompanying drawings.

66 6 6 6 6 6 66 Dated this 30th day of April 1982 66 6 6

F_ L_ L'

AYRSHIRE METAL PRODUCTS LIM4ITED -By their Patent Attorney 6 66 6 GRIFFITH, HASSEL FRAZER 6 V 66 66 C

F 96 r 6 66 6

6 96 6 6

;es purlins

antially

and 2 of the

ntially

and 4 of the

83 198/2

a, a a

0*89 8 4 a 00 a

a 09S0*0 a *8 48 o a 0 Q

.0 8* 8 8

a *0 a a 0 a FIG.I. a a a ow

88 a a a @8o a

0e *4 a a a 4 8

FIG.2.

C,

22-

6e 9 0

*900 S p FIG.3. we S

.9 Sw 0p S

09 C 9 *5

9. 9 w~ CS

*0 S 9 PS

S 49 C 905 9

ow S. 9.9 p S

b FIG. 5b.

r