Selecting the correct beam -...

2

W = 47

D = 100

W = 47

W = 47

F100 F150 F200

t

D = 150

D = 200

2t

tt

2t

2t

LYSAGHT FIRMLOK

IdentificationThe format of the number code is:

F xxx xx

F=Firmlok xxx = Section xx = 2 t x 10depth D (mm) (mm)

Material specificationsFIRMLOK beams are made fromZINCALUME® aluminium/zinc alloy-coated steel complying with AS1397—1993 G550, AZ150 (550 MPaminimum yield stress, 150 g/m2

minimum coating mass).

The base metal thicknesses are 0.55,0.75 and 1.00 mm.

The COLORBOND® prepainted steelcomplies with AS/NZS 2728:1997.

LengthsStock lengths of FIRMLOK beams are4000, 5000, 6100, 7500 and9000 mm.

Extended lead times may apply fornon-standard lengths between 1,000mm and 12,000 mm.

TolerancesDepth = ± 1 mm

Width = ± 1 mm

Length = + 0, -5 mm

seziSnoitceS snoisnemiD

lateMssenkciht

noitceSaera

ssaM)dnobroloC(

WxD t)mm( )mm( mm( )2 )m/gk(

11001F 74x001 55.0 3.432 49.1

51051F 74x051 57.0 0.393 12.3

02002F 74x002 00.1 0.026 10.5

3

Introduction

Four tables help you select from the popular range of FIRMLOK beams.Of course engineers can still use the whole range of FIRMLOK beams,calculating strengths from firstprinciples and section properties.

Rafters run parallel to the ribs onyour cladding, and have purlinsattached.

Purlins run at ninety degrees to theribs on your cladding, and areconnected at each end to raftersand/or posts. They have claddingattached to their top face.

Wind classification

Find out the wind classification foryour site—N1 (W28), N2 (W33) or N3(W41)—your local building approvalauthority will know. AS 4055 Windloads for housing details theseclassifications.

Dimensions

Refer to your plans or sketch of thejob. Check you have the span andspacing dimensions (see alsodiagrams on Pages 4 and 6).

Selecting the correct beam

RafterFascia purlin

Purlin

Purlin

Select your purlins and rafters

For flat roofs, use the tables on Pages4 and 5; or for pitched roofs, use thetables on Pages 6 and 7.

• Determine the maximum spacing ofpurlins (see table on Page 9), orrafters for the desired roof profile.

• Determine the number of purlinsyou need.

• Determine the size of rafter youneed using a table on either Page 5or 7.

• Check the purlin size using a tableon either Page 4 or 6.

Fascia purlins

The fascia-end of every rafter issupported by a post, though you may delete intermediate posts if thefascia purlin is big enough. To designyour fascia purlins: if the end of eachrafter is:

• supported by a post, use a table onPages 4 (for flat roof) or 6;

• not supported by a post, use atable on Pages 5 (for flat roof) or 7.

In each case, enter the body of thetable with a number that is 60% ofthe actual rafter span, to find themaximum span for your fascia purlinin the left-hand column (the 60%allows for local pressure factors).

Design conditions

Always check that your designsconform with the notes on the tablesand those on Pages 9 and 10.

Worked examples:

See Pages 11 and 12.

Brackets & fasteners:

See Page 8.

Flat roofs

Purlin spacing

Rafter span

Rafter spacing & purlin span

Purlin

Rafter

Rafter

Rafter

Purlin

Purlin spacing

Rafter spacing & purlin span

Maximumpitch 5°

Flat roofs may be free-standingor attached to another structure

Flat roof purlins• If your purlin span falls between

two listed values, don’t estimate avalue — always use the moreconservative (lesser) listed value.

• The top face of purlins must belevel with the top face of therafters, and must be restrained bythe roofing fixed in accordancewith our published data for theroofing being used.

• The spacing of purlins is oftengoverned by the maximumallowable support spacing for theroof cladding you are using (seethe table on Page 9). For aestheticreasons, purlins should beequispaced.

)mm(gnicapsnilrupelbawollamumixaM

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snoitacifissalcdniW)33W(2N&)82W(1N

noitacifissalcdniW)14W(3N

snoitceskolmriF snoitceskolmriF

11001F 51051F 02002F 11001F 51051F 02002F0571 00040002 00530522 0554 0292

0052 0863 0732 09340572 0403 0691 00040003 0652 0461 0663

0523 0812 0041 08330053 0881 0654 0121 03920573 0461 0793 0501 0552

0004* 0441 0943 039 0522 05240524 0321 0903 0991 02930054 0301 0672 0771 0943

0574 0842 0951 04130005* 0322 0044 0441 03820525 0302 0993 0031 0752

0055 0581 0463 0911 04320575 0961 0333 0901 04120006 0551 0603 0001 0791

0526 0931 0282 029 01810056 0421 0062 07610576 0111 0142 0551

0007 099 0422 04410527 0902 05310057* 0691 0621

0577 0381 08110008 0271 01110528 0261 0401

0058 0941 0890578 0731 0290009* 0621

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Flat roof rafters

• If your rafter span falls betweentwo listed values, don’t estimate a value — always use the moreconservative (lesser) listed value.

• Rafters must be single spans withno intermediate supports.

• For purlin spacings greater than2400 and up to 3000 mm, multiplyvalues given for 2400 spacings by 0.76.



)mm(gnicapsretfarelbawollamumixaMsnoitacifissalcdniW

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retfaRnaps)mm(

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0081 0042 0081 0042 0081 0042 0081 0042 0081 0042 0081 0042

0571 0009 0009 0571 0856 08560002 0877 0167 0002 0594 0484 0009 00090522 0806 0675 0522 0783 0763 0958 0458

0052 0784 0154 0009 0052 0013 0782 0137 04660572 0993 0763 0009 0748 0572 0452 0432 0895 0045 00090003 0233 0403 0187 0007 0003 0112 0491 0794 0644 0009 0238

0523 0972 0552 0956 0785 0523 0871 0361 0024 0473 0208 07960053 0322 0712 0365 0994 0009 0053 0151 0831 0853 0813 0586 01950573 0181 0181 0684 0824 0009 0597 0573 0321 0911 0903 0272 0295 0605

0004* 0941 0941 0324 0173 0018 0886 0004* 0101 0101 0072 0632 0515 08340524 0421 0421 0273 0423 0117 0006 0524 0732 0602 0354 02830054 0401 0401 0923 0582 0926 0725 0054 0012 0181 0104 0633

0574 0392 0252 0165 0664 0574 0781 0161 0753 07920005* 0362 0522 0205 0514 0005* 0761 0341 0023 04620525 0632 0102 0354 0173 0525 0151 0821 0882 0632

0055 0602 0181 0014 0433 0055 0631 0511 0162 02120575 0081 0461 0273 0103 0575 0221 0401 0732 02910006 0851 0841 0043 0372 0006 0701 059 0612 0471

0526 0041 0531 0113 0942 0526 059 0891 08510056 0421 0321 0682 0722 0056 0281 05410576 0111 0111 0462 0802 0576 0861 0331

0007 0001 0001 0442 0191 0007 0551 02210527 0622 0671 0527 0441 02110057* 0112 0361 0057* 0431 0401

0577 0691 0151 0577 0521 0690008 0971 0041 0008 07110528 0361 0131 0528 0901

0058 0941 0221 0058 01010578 0731 0411 0578 0390009* 0621 0601 0009*

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5

Pitched roofs

Rafter spacing

Rafter spacing

Purlin spacing

Purlin spacing

Frame span

Rafter

Rafter

Purlin

Purlin

Rafter length

Frame span

Pitch °

Rafter length for 15° pitch = 0.518 Frame spanRafter length for 22.5° pitch = 0.541 Frame span

Pitched-roof purlins• If your purlin span falls between

two listed values, don’t estimate avalue — always use the moreconservative (lesser) listed value.

• The top face of purlins must belevel with the top face of therafters, and must be restrained bythe roofing fixed in accordancewith our published data for theroofing being used.

• The spacing of purlins is oftengoverned by the maximumallowable support spacing for theroof cladding you are using (seethe table on Page 9). For aestheticreasons, purlins should beequispaced.

)mm(gnicapsnilrupelbawollamumixaM

nilruPnaps)mm(

snoitacifissalcdniW)33W(2N&)82W(1N

noitacifissalcdniW)14W(3N

snoitceskolmriF snoitceskolmriF

11001F 51051F 02002F 11001F 51051F 02002F0571 0534 0282 03440002 0183 0742 08830522 0913 0602 0543

0052 0852 0761 00130572 0312 0534 0831 0282 06340003 0971 0993 0611 0852 0993

0523 0351 0863 099 0832 09630053 0231 0913 0702 02430573 0511 0872 0081 0913

0004* 0101 0542 0851 09920524 0712 0724 0041 06720054 0391 0183 0521 0742

0574 0371 0243 0211 01220005* 0751 0803 0101 00020525 0241 0082 029 0181

0055 0921 0552 05610575 0811 0332 01510006 0901 0412 0931

0526 0001 0791 08210056 0281 08110576 0961 0011

0007 0751 02010527 0741 0590057* 0731

0577 08210008 00210528 0311

0058 06010578 0890009*

)nwohstonsi0016fohtgnelkcotS(.shtgnelkcotS*6

Pitched-roof rafters• If your rafter span falls between

two listed values, don’t estimate a value — always use the moreconservative (lesser) listed value.

• Rafters must be single spans withno intermediate supports.




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0571 0817 0817 0571 0264 0264 0009 00090002 0145 0925 0002 0843 0043 0327 03270522 0224 0004 0009 0009 0522 0272 0752 0306 0006 0009 0009

0052 0933 0313 0897 0527 0052 0812 0102 0315 0664 0938 09380572 0772 0552 0256 0985 0572 0871 0461 0024 0973 0237 08070003 0132 0112 0345 0784 0009 0009 0003 0841 0631 0943 0313 0866 0485

0523 0591 0771 0854 0804 0678 0067 0523 0521 0411 0492 0262 0365 09840053 0951 0151 0193 0743 0847 0546 0053 0701 079 0152 0322 0184 05140573 0921 0921 0833 0792 0646 0255 0573 0712 0191 0514 0553

0004 0601 0601 0492 0852 0265 0874 0004 0981 0661 0263 07030524 0852 0522 0494 0714 0524 0661 0541 0813 08620054 0922 0891 0734 0663 0054 0741 0721 0182 0532

0574 0402 0571 0093 0423 0574 0131 0311 0052 08020005 0281 0651 0943 0882 0005 0711 0001 0522 05810525 0461 0041 0413 0852 0525 0202 0661

0055 0741 0621 0582 0232 0055 0381 09410575 0921 0411 0952 0902 0575 0661 05310006 0311 0301 0632 0091 0006 0251 0221

0526 0001 049 0612 0371 0526 0931 01110056 0991 0851 0056 0821 01010576 0381 0541 0576 0811 039

0007 0071 0331 00070527 0751 0321 05270057 0641 0311 0057

0577 0631 0501 05770008 0721 079 00080528 0711 019 0528

0058 0701 00580578 089 05780009 0009

7

ConnectionsLysaght Firmlok universal bracketsFix with self-drilling metal Teks screwswith hexagon washer head andHiteks drill point to AS 3566 Class 3,10-16 x 16 mm.

For each bracket use:

• 12 screws for wind classificationsN2 (W33) and N3 (W41);

• 8 screws for wind classificationN1 (W28).

For holes: minimum edge distance is10 mm; and minimum centre tocentre distance is 15 mm.

Lysaght Firmlok apex bracketsFix with self-drilling metal Teks screwswith hexagon washer head andHiteks drill point to AS 3566 Class 3,14-20 x 22 mm.

For each bracket use:

• 24 screws for wind classificationsN2 (W33) and N3 (W41);

• 20 screws for wind classificationN1 (W28).

For holes: minimum edge distance is10 mm; and minimum centre tocentre distance is 20 mm.

Universal brackets for different pitches0° to 5° 15° 22.5°

20 mm

10 mmmin.

VIEW 'X'Placing of screws

for fixing of brackets

VIEW 'X'

A AA

A

A

Screws at positions 'A' may be omittedfor wind conditions N1 (W28)

15 mmmin. A

A

15 mmmin.

10 mmmin.

Apex bracket is availablefor 15° and 22.5° pitches

On all 4 faces of bracket:For wind classificationsN1 (W28) use 5 screws

N2 (W33) & N3 (W41) use 6 screws

2525

2525

Screws at20 mm centres

Firmlok mustbe mitred

8

Design conditions for the tablesBasis of design

The connection and beam capacitiesare based on limit state design andtesting in our laboratory. Theyconform with AS/NZS 4600:1996Cold-formed steel structures.

Design information is taken from:

AS 1170.1—1989 Dead and live loads

AS 1170.2—1989 Wind loads

AS 3623—1993 Domestic metalframing

AS 4055—1992 Wind loads forhousing

For more detailed information orcommentary on these loads, refer tothese standards.

Dead loads

A dead load of 0.1 kPa has beenincluded. No allowance has beenmade for ceilings.

Live loads

The tables are for roof structureswhich are non-trafficable (AS 1170.1).Use crawl boards to distribute loadsand prevent damage to roofcladding during installation andmaintenance.

Wind loads

Three maximum design gust windspeeds from AS 4055, have beenused for the tables as follows:

The local pressure factors have beenassumed for intermediate supportingmembers (purlins) as defined in AS1170.2.

Serviceability

The criteria used are:

• Dead load: Span/300

• Wind load: Span/150

Connection capacity

The connections have been verifiedby testing at our NATA-registeredlaboratory.

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Endspan

Internalspan

Endspan

Single span

Span types

9

Posts50 x 50 x 2.5 mm square tubular steelposts are structurally adequate for allloadings covered by these tables—larger sizes may be considered foraesthetic reasons.

Connection to another structureWhere a flat roof is to be attached toanother structure, seek advice froman engineer to obtain connectiondetails and to ensure that the otherstructure is capable of withstandingany additional loading.

Non-cyclonic areasThe information in this brochure issuitable for use only in areas where atropical cyclone is unlikely to occur asdefined in AS 1170.2—1989 SAALoading Code, Part 2: Wind Loads.

Seek advice from an engineer fordesigns to be used in cyclonic areas.

Storage and handlingKeep the product dry and clear of the ground. If stacked or bundledproduct becomes wet, separate it,wipe it with a clean cloth and stack it to dry thoroughly.

Handle materials carefully to avoiddamage: don’t drag materials overrough surfaces or each other; carry tools, don’t drag them; protect from swarf.

CuttingFor cutting thin metal on site, werecommend a circular saw with ametal-cutting blade because itproduces fewer damaging hot metalparticles and leaves less resultant burr than does a carborundum disc.

Cut materials over the ground and notover other materials.

Sweep all metallic swarf and otherdebris from roof areas and gutters at the end of each day and at thecompletion of the installation. Failure to do so can lead to surfacestaining when the metal particles rust.

Use, care and cutting of FIRMLOK

Adverse conditions If this product is to be used inmarine, severe industrial, or unusuallycorrosive environments (closer than1000 metres) seek advice from ourinformation line.

Metal & timber compatibilityLead, copper, bare steel and green orsome chemically-treated timbers arenot compatible with this product;thus don’t allow any contact of theproduct with those materials, nordischarge of rainwater from themonto the product. If there are doubtsabout the compatibility of otherproducts being used, seek advicefrom our information line.

Strippable coatingsSome COLORBOND® STEEL products arecoated with a protective plastic film.Remove this film at the time ofinstallation, or you may find it veryhard to remove later on.

10

1. Purlin spacing

Maximum purlin support spacings forFLATDEK, in N2 wind classification =3600 mm (from table on page 9).

Number of cladding spans

= (Awning width)/(Max. supportspacing

= 4800/3600 = 1.33 spans

Round to 2 spans of 4800/2 =2400 mm

2. Size of rafters

Span of rafters is 4800 mm.

Purlin spacing = Cladding span =2400 mm

The table on Page 5 allows us to useF15015 or F20020.

2.1 Try F15015

Because a rafter span of 4800 mm isnot shown in the table, try 5000 mmfor which the maximum rafterspacing = 2250 mm.

Number of purlin spans

= (Awning breadth)/ (Max. rafterspacing)

= 8000/2250 = 3.6

Round up to 4 purlin spans of 8000/4= 2000 mm.

For 4 purlin spans we need 5 rafters.

2.2 Try F20020

For a rafter span of 4800 mm, try5000 mm for which the maximumrafter spacing = 4150 mm.


= (Awning breadth)/ (Max. rafterspacing)

= 8000/4150 = 1.9

Round up to 2 purlin spans of 8000/2= 4000 mm.

For 2 purlin spans we need 3 rafters.

Worked example 1

3. Check purlin sizeUsing option 2.1

Purlin span = Rafter spacing =2000 mm

Enter the body of the table on Page4 and look under F10011 for thevalue that is equal to or higher than2400 (see Step 1). The value you findis 2560; and the purlin span for thatvalue is 3000 (in the left-handcolumn). Since 3000 mm is greaterthan 2000 mm, the F10011 beam isadequate.

Using option 2.2

Purlin span = Rafter spacing =4000 mm

Enter the body of the table on Page4 and look under F10011 for thevalue that is equal to or higher than2400 (see Step 1). The value you findis 2560; and the purlin span for thatvalue is 3000 (in the left-handcolumn). Since 3000 mm is less than4000 mm, the F10011 beam is notadequate, so try a larger beam.

Again enter the body of the table onPage 4 and look under F15015 forthe value that is equal to or higherthan 2400. The value you find is2480; and the purlin span for thatvalue is 4750 (in the left-handcolumn). Since 4750 mm is greaterthan 4000 mm, the F15015 beam isadequate.

Observation

Option 2.2 uses fewer rafters and posts.

SpecificationDesign an awning attached to abuilding, using FLATDEK® at 2° pitch, ina wind classification area of N2(W33), with no foot traffic (seedrawing).

4. Size of fascia purlin

The end of every rafter must besupported, either by a post or by afascia purlin.

To reduce the number of posts, youcan use a fascia purlin bigger thandetermined in previous steps.Removing posts, adds concentratedloads on the purlin, so the rafter tablemust be used for the fascia (becausethat table allows for concentratedloads).

Checking option 2.1

(For F15015 rafters)

To delete 2 posts, a fascia purlin mustspan a distance of 2 x Rafter spacing.That is,

Fascia purlin span = 2 x 2000 =4000 mm

Accounting for local pressure factors,the equivalent purlin spacing is 60% ofthe actual rafter span, that is 4800 x0.6 = 2880 mm

Enter the body of the table on Page 5and look under F15015 for the valuethat is equal to or higher than 2880.The value you find is 3240; and therafter span for that value is 4250 (inthe left-hand column).

Since 4250 mm is greater than 4000mm, the F15015 beam is adequate,thus 3 posts could be used instead of5. (For uniformity, F15015 could beused for all members.)

Breadth = 8000

Wid

th =

480

0

Purlins

Rafters

Flat

dek

ribs

Posts

11

Worked example 2

1. Purlin spacing

Maximum support spacings forFLATDEK, in N2 wind classification =3600 mm (from table on page 9).Thus no intermediate purlin isrequired.

2. Purlin size

Taking the local pressure factors intoaccount, the fascia purlin supports60% of the load on the awning. Thus:

Equivalent purlin spacing

= Awning width x 0.6

= 3600 x 0.6 = 2160 mm.

From table on Page 4, we could useeither:

Option 2.1 (F15015)

In the body of the table, find thepurlin spacing equal to, or greaterthan, 2160 mm: that is 2230 mm

This gives a maximum allowablepurlin span = 5000 mm.


= (Awning breadth)/ (Max. purlinspacing)

= 12000/5000 = 2.4

Round up to 3 purlin spans of12000/3 = 4000 mm.

SpecificationDesign an awning attached to abuilding, using FLATDEK at 2° pitch, in a wind classification area ofN2 (W33), with no foot traffic (see drawing).

Option 2.2 (F20020)

In the body of the table, find thepurlin spacing equal to, or greaterthan, 2160 mm: that is 2240 mm

This gives a maximum allowablepurlin span = 7000 mm.


= (Awning breadth)/ (Max. purlinspacing)

= 12000/7000 = 1.7

Round up to 2 purlin spans of12000/2 = 6000 mm, which require3 posts.

Breadth = 12000

Wid

th =

360

0Purlin

Rafters

Flat

dek

ribs

Posts

Conclusion

Using F20020 uses fewer posts.

3. Size of rafters

Because there are no intermediatepurlins, the rafters don’t support anyvertical loads imposed by thestructure or wind. Thus you could usean F10011 as a minimum.

© Copyright BlueScope Steel Limited 22 September 2003

LYSAGHT®, COLORBOND®, FIRMLOK®, ZINCALUME® & FLATDEK®are trademarks of BlueScope Steel Limited

A.B.N. 16 000 011 058

The LYSAGHT® range of products is exclusively made byBlueScope Steel Limited trading as BlueScope Lysaght.

Information, brochures andyour local distributor

1800 641 417

Please check the latest informationwhich is always available at

www.lysaght.com

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