7/05/13'

1'

Timber – connecting inspiration and design

Dr Geoff Boughton

Project'::'Na+onal'Portrait'Gallery'Architects,::'Johnson'Pilton'Walker'Loca/on'::'Canberra,'ACT''

7/05/13'

2'

Project'::'Na+onal'Portrait'Gallery'Architects,::'Johnson'Pilton'Walker'Loca/on'::'Canberra,'ACT''

Project'::'Na+onal'Portrait'Gallery'Architects,::'Johnson'Pilton'Walker'Loca/on'::'Canberra,'ACT''

7/05/13'

3'

Project,::'Exhibi+on'Centre'Architects'::''Ancher'Mortlock''&'Woolley'Loca/on'::'Homebush,'NSW'

Project,::'Exhibi+on'Centre'Architects'::''Ancher'Mortlock''&'Woolley'Loca/on'::'Homebush,'NSW'

7/05/13'

4'

Project,::,Waitomo'Caves'Visitors''Centre'Architect,::,Architecture'Workshop'Loca/on,::,Otorohanga,'New'Zealand'

Project,::,Waitomo'Caves'Visitors''Centre'Architect,::,Architecture'Workshop'Loca/on,::,Otorohanga,'New'Zealand'

7/05/13'

5'

Project,::'Richmond'Olympic'Oval'Architect'::'Cannon'Design'Engineer,::'Fast'&'Epp'Loca/on'::'Richmond,'Canada''

Project,::'Richmond'Olympic'Oval'Architect'::'Cannon'Design'Engineer,::'Fast'&'Epp'Loca/on'::'Richmond,'Canada''

7/05/13'

6'

Project,::'Richmond'Olympic'Oval'Architect'::'Cannon'Design'Engineer,::'Fast'&'Epp'Loca/on'::'Richmond,'Canada''

Project''::'Expo'2000'roof'–'Hanover'Architect'::'Prof.'T.'Herzog'|'H.'J.'Schrade'|'IEZ'Na^er'GmbH'Engineer'::'IEZ'Na^er'GmbH'Loca/on,::'Hanover,'Germany''Image,::'Frank''Boller'

7/05/13'

7'

Project''::'Expo'2000'roof'–'Hanover'Architect'::'Prof.'T.'Herzog'|'H.'J.'Schrade'|'IEZ'Na^er'GmbH'Engineer'::'IEZ'Na^er'GmbH'Loca/on,::'Hanover,'Germany''

Project''::'John'Niland'Scien+a'Building'Architect'::'ARINA'Architects'Engineer'::''Loca/on,::'University'of'New'South'Wales,'Sydney'

7/05/13'

8'

Project'::'Centre'Pompidoub'Metz'Architect'::'Shigeru'ban'Architects'Engineer'::'Arup'Engineer'Loca/on'::''Metz,'France'Image'::'Shigeru'ban'Architects'

Project'::'Centre'Pompidou'b'Metz'Architect'::'Shigeru'ban'Architects'Engineer'::'Arup'Engineer'Loca/on'::''Metz,'France'Image'::'Shigeru'ban'Architects'

7/05/13'

9'

Project'::'Centre'Pompidoub'Metz'Architect'::'Shigeru'ban'Architects'Engineer'::'Arup'Engineer'Loca/on'::''Metz,'France'Image'::'Shigeru'ban'Architects'

Project'::'Centre'Pompidoub'Metz'Architect'::'Shigeru'ban'Architects'Engineer'::'Arup'Engineer'Loca/on'::''Metz,'France'Image'::'Shigeru'ban'Architects'

7/05/13'

10'

Project'::'Centre'Pompidoub'Metz'Architect'::'Shigeru'ban'Architects'Engineer'::'Arup'Engineer'Loca/on'::''Metz,'France'Image'::'Shigeru'ban'Architects'

Project,::,Aurland'Look'Out'Architect,::,Saunders'Architecture'Loca/on,::,Aurland,'Norway'Image,::,Todd'Saunders'

7/05/13'

11'

Project,::,Aurland'Look'Out'Architect,::,Saunders'Architecture'Loca/on,::,Aurland,'Norway'Image,::,Todd'Saunders'

Project,::,Aurland'Look'Out'Architect,::,Saunders'Architecture'Loca/on,::,Aurland,'Norway'Image,::,Todd'Saunders'

7/05/13'

12'

Project,::'Sport'Court''Architect,::'E.'Comnarel''D.'Marrec'Engineer'::'BETIBA'Bureau'd’Etudes'Techniques'Loca/on'::'Lycée'La'Tourelle,'France'Image'::'Philippe'Ruault'

Project,::'Sport'Court''Architect,::'E.'Comnarel''D.'Marrec'Engineer'::'BETIBA'Bureau'd’Etudes'Techniques'Loca/on'::'Lycée'La'Tourelle,'France'Image'::'Philippe'Ruault'

7/05/13'

13'

Project,::'Sport'Court''Architect,::'E.'Comnarel''D.'Marrec'Engineer'::'BETIBA'Bureau'd’Etudes'Techniques'Loca/on'::'Lycée'La'Tourelle,'France'Image'::'Philippe'Ruault'

What do you need to know to be able to design something like that?

7/05/13'

14'

Bolted connections

•  Type 1 – shear in the bolt

•  Type 2 – tension in the bolt

Capacity of Type 1 Bolted connections AS1720.1 4.4.3.2

•  φ - capacity factor Table 2.2 !  type of structure, element !  different for small and larger diameter bolts

•  k1- duration of load factor Table 2.3 !  given by shortest duration load in the combination

•  k16- side plate factor !  stiff side-plates and close-fitting holes can

prevent rotation of bolt

•  n - total number of bolts in joint

Nd,j = φk1k16k17nQsk

7/05/13'

15'

k17 Multiple bolt factor

AS1720.1 Table 4.12

•  Large difference in k17 for bolts in seasoned and unseasoned timber

•  Seasoned timber dimensionally stable !  no shrinkage hence k17 = 1

•  Unseasoned timber used in dry conditions becomes partially seasoned !  leads to shrinkage perpendicular to grain !  where restrained, can cause cracking, k17 = 0.5 !  where unrestrained, k17 depends on number of rows

- e.g. one bolt per row

Nd,j = φ k1k16k17nQsk

Capacity of Type 1 Bolted connections

Qsk – characteristic system capacity of a single joint

•  Joint strength group from species of timber

•  Different capacities for angle between load and grain

!  Qskl – system capacity parallel to grain – sum of all Qkl for the shear planes on one bolt in the connection Table 4.9

!  Qskp – system capacity perpendicular to grain – sum of all Qkp (load to grain) for the shear planes on one bolt in the connection Table 4.10

Nd,j = φ k1k16k17nQsk

QQ Q

Q Qskskl skp

skl skpθ θ θ=

+sin cos2 2

7/05/13'

16'

Characteristic bolt capacity

JD2 - JD5

Direction of force

14 500

Timber thickness

beff

Bolt Size

Species Joint

Strength Group

TABLE 4.9(C)

CHARACTERISTIC CAPACITY FOR SINGLE BOLTS PARALLEL TO GRAIN - SEASONED TIMBER

Characteristic capacity, Qkl, N

Bolt diameterSpeciesGroup

Effect

timber

thickness

beff, mmM6 M8 M10 M12 M16 M20 M24 M30 M36

JD1 25 4 100 6 900 8 600 10 400 13 800 17 300 20 700 25 900 31 100

35 4 100 7 300 11 400 14 500 19 300 24 200 29 000 36 200 43 500

40 4 100 7 300 11 400 16 400 22 100 27 600 33 100 41 400 49 700

45 4 100 7 300 11 400 16 400 24 800 31 100 37 300 46 600 55 900

70 4 100 7 300 11 400 16 400 29 100 45 500 58 000 72 500 86 900

90 4 100 7 300 11 400 16 400 29 100 45 500 65 600 93 200 111 800

105 4 100 7 300 11 400 16 400 29 100 45 500 65 600 102 500 130 400

120 4 100 7 300 11 400 16 400 29 100 45 500 65 600 102 500 147 500

JD2-JD5

JD6 25 1700 2 200 2 800 3 300 4 400 5 500 6 600 8 300 9 900

35 1900 3 100 3 900 4 600 6 200 7 700 9 200 11 600 13 900

40 1900 3 400 4 400 5 300 7 000 8 800 10 600 13 200 15 800

105 1900 3 400 5 300 7 600 13 500 21 100 27 700 34 700 41 600

120 1900 3 400 5 300 7 600 13 500 21 100 30 400 39 600 47 500

Capacity of Type 2 bolted connections

Capacity is lesser of

•  Bolt failure

•  Wood crush failure !  Serviceability failure rather than a separation of the members

!  k7 - bearing area factor

!  f 'pj - crushing strength under fasteners (confined bearing strength) larger than f 'p (unconfined bearing strength)

Nd,j = n Nd,tb

Nd,j = φ k1k7n f 'pj Aw

AS1720.1 4.4.3.3

7/05/13'

17'

Detailing bolted connections

Distances measured centre-to-centre

•  Minimum end distances – measured parallel to grain

•  Minimum edge distances – measured perpendicular to grain

•  Spacing parallel to grain

•  Spacing perpendicular to grain

Washers

•  Minimum size and thickness

Variations

•  Coach screws

•  Dowels

•  Dowelled fin plates

7/05/13'

18'

Fire

•  Timber burns, but slowly and from outside in. !  Charring on outside protects timber inside

!  Wood acts as an insulator

•  Timber member fire design philosophies !  Sacrificial timber – oversized members char – leave residual

section that can carry fire limit states loads

!  Protect timber structural elements with

�  Plasterboard

�  Other non-structural timber

•  Connections !  Steel as a conductor if part exposed to fire

Connections in fire

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19'

Problems for timber connections

•  Steel fasteners !  soften with temperature and become more flexible

!  transfer heat into the members

!  potential for premature failure and loss of structural integrity

•  Glues !  may deteriorate at high temperatures

Strategies

Ensure connections are not weakest link

•  Make sure connections have higher fire ratings than members

•  Alternatives !  protect connections behind plasterboard

!  place sacrificial timber between connections and the potential fire – either plugs or plates

!  use 100% timber connections eg timber dowels

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20'

Plasterboard

Plasterboard

•  Connections are part of tested system

•  Cover and protect the connection as though it is timber

•  Care at corners, penetrations and junctions (use fire-resistant sealant – fire-grade flexible material filling gaps)

•  Extra layers at connections ensure fasteners are not the weakest link

7/05/13'

21'

Plasterboard

Fire protection coverings: !  13 mm fire-grade plasterboard

!  12 mm cellulose fire-reinforced cement sheeting complying with AS2908.2

!  12 mm fibrous plaster reinforced with 13 mm x 13 mm x 0.7 mm galvanised steel with mesh located not more than 6 mm from the exposed face

!  Other material equivalent to 13 mm fire-grade plasterboard

!

•  Protection by: o  surface

protection or o  embed fixings

under plugs

•  Other protection measures need test data to support their use

Plugs

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22'

Plates

Plates

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23'

Plates

•  Thickness of the plate is sacrificial depth of timber for charring

•  Cover the connection as though it is timber

•  Care at corners, penetrations and junctions (use fire-resistant sealant – fire-grade flexible material filling gaps)

•  Extra layers at connections ensure fasteners are not the weakest link

Timber dowels

7/05/13'

24'

Timber dowels

•  Substitute for steel (steel may soften in fire)

•  Dowels char in same way and rate as member

Conclusions

•  Timber can be used for large, interesting commercial and iconic structures

•  Many different types of timber systems can be used for elegant structural solutions

•  Connections are important in the realisation of the structural scheme and are often part of the early concept designs

•  A lot can be achieved with the standard bolt if used sensibly

•  Fire protection by sacrificial timber or oversizing

7/05/13'

25'

Other information

•  Handbook 108-2013 (Standards Australia)

•  Wood Solutions website www.woodsolutions.com.au

•  Two-day UTas Masterclass

Perth, 2 and 3 May, 2013

AS1720 Timber Engineering Master Class April/May 2013