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
May 16, 2015
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
7/05/13'
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
7/05/13'
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
7/05/13'
22'
Plates
Plates
7/05/13'
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