Timber Connections reduced by Geoff Boughton

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Timber Connections reduced by Geoff Boughton

  1. 1. 7/05/131Timber –connecting inspiration and designDr Geoff BoughtonProject::Na+onalPortraitGalleryArchitects,::JohnsonPiltonWalkerLoca/on::Canberra,ACT
  2. 2. 7/05/132Project::Na+onalPortraitGalleryArchitects,::JohnsonPiltonWalkerLoca/on::Canberra,ACTProject::Na+onalPortraitGalleryArchitects,::JohnsonPiltonWalkerLoca/on::Canberra,ACT
  3. 3. 7/05/133Project,::Exhibi+onCentreArchitects::AncherMortlock&WoolleyLoca/on::Homebush,NSWProject,::Exhibi+onCentreArchitects::AncherMortlock&WoolleyLoca/on::Homebush,NSW
  4. 4. 7/05/134Project,::,WaitomoCavesVisitorsCentreArchitect,::,ArchitectureWorkshopLoca/on,::,Otorohanga,NewZealandProject,::,WaitomoCavesVisitorsCentreArchitect,::,ArchitectureWorkshopLoca/on,::,Otorohanga,NewZealand
  5. 5. 7/05/135Project,::RichmondOlympicOvalArchitect::CannonDesignEngineer,::Fast&EppLoca/on::Richmond,CanadaProject,::RichmondOlympicOvalArchitect::CannonDesignEngineer,::Fast&EppLoca/on::Richmond,Canada
  6. 6. 7/05/136Project,::RichmondOlympicOvalArchitect::CannonDesignEngineer,::Fast&EppLoca/on::Richmond,CanadaProject::Expo2000roof–HanoverArchitect::Prof.T.Herzog|H.J.Schrade|IEZNa^erGmbHEngineer::IEZNa^erGmbHLoca/on,::Hanover,GermanyImage,::FrankBoller
  7. 7. 7/05/137Project::Expo2000roof–HanoverArchitect::Prof.T.Herzog|H.J.Schrade|IEZNa^erGmbHEngineer::IEZNa^erGmbHLoca/on,::Hanover,GermanyProject::JohnNilandScien+aBuildingArchitect::ARINAArchitectsEngineer::Loca/on,::UniversityofNewSouthWales,Sydney
  8. 8. 7/05/138Project::CentrePompidoubMetzArchitect::ShigerubanArchitectsEngineer::ArupEngineerLoca/on::Metz,FranceImage::ShigerubanArchitectsProject::CentrePompidoubMetzArchitect::ShigerubanArchitectsEngineer::ArupEngineerLoca/on::Metz,FranceImage::ShigerubanArchitects
  9. 9. 7/05/139Project::CentrePompidoubMetzArchitect::ShigerubanArchitectsEngineer::ArupEngineerLoca/on::Metz,FranceImage::ShigerubanArchitectsProject::CentrePompidoubMetzArchitect::ShigerubanArchitectsEngineer::ArupEngineerLoca/on::Metz,FranceImage::ShigerubanArchitects
  10. 10. 7/05/1310Project::CentrePompidoubMetzArchitect::ShigerubanArchitectsEngineer::ArupEngineerLoca/on::Metz,FranceImage::ShigerubanArchitectsProject,::,AurlandLookOutArchitect,::,SaundersArchitectureLoca/on,::,Aurland,NorwayImage,::,ToddSaunders
  11. 11. 7/05/1311Project,::,AurlandLookOutArchitect,::,SaundersArchitectureLoca/on,::,Aurland,NorwayImage,::,ToddSaundersProject,::,AurlandLookOutArchitect,::,SaundersArchitectureLoca/on,::,Aurland,NorwayImage,::,ToddSaunders
  12. 12. 7/05/1312Project,::SportCourtArchitect,::E.ComnarelD.MarrecEngineer::BETIBABureaud’EtudesTechniquesLoca/on::LycéeLaTourelle,FranceImage::PhilippeRuaultProject,::SportCourtArchitect,::E.ComnarelD.MarrecEngineer::BETIBABureaud’EtudesTechniquesLoca/on::LycéeLaTourelle,FranceImage::PhilippeRuault
  13. 13. 7/05/1313Project,::SportCourtArchitect,::E.ComnarelD.MarrecEngineer::BETIBABureaud’EtudesTechniquesLoca/on::LycéeLaTourelle,FranceImage::PhilippeRuaultWhat do you need to know to be able to designsomething like that?
  14. 14. 7/05/1314Bolted connections•  Type 1 – shear in the bolt•  Type 2 – tension in the boltCapacity of Type 1 Bolted connectionsAS1720.1 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 canprevent rotation of bolt•  n - total number of bolts in jointNd,j = φk1k16k17nQsk
  15. 15. 7/05/1315k17 Multiple bolt factorAS1720.1 Table 4.12•  Large difference in k17 for bolts in seasoned andunseasoned timber•  Seasoned timber dimensionally stable!  no shrinkage hence k17 = 1•  Unseasoned timber used in dry conditions becomespartially 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 rowNd,j = φ k1k16k17nQskCapacity of Type 1 Bolted connectionsQsk – characteristic system capacity of a single joint•  Joint strength group from species of timber•  Different capacities for angle between load andgrain!  Qskl – system capacity parallel to grain – sum of all Qkl for theshear planes on one bolt in the connection Table 4.9!  Qskp – system capacity perpendicular to grain – sum of allQkp (load to grain) for the shear planes on one bolt in theconnection Table 4.10Nd,j = φ k1k16k17nQskQQ QQ Qskskl skpskl skpθθ θ=+sin cos2 2
  16. 16. 7/05/1316Characteristic bolt capacityJD2 - JD5Direction offorce14 500TimberthicknessbeffBolt SizeSpeciesJointStrengthGroupTABLE 4.9(C)CHARACTERISTIC CAPACITY FOR SINGLE BOLTSPARALLEL TO GRAIN - SEASONED TIMBERCharacteristic capacity, Qkl, NBolt diameterSpeciesGroupEffecttimberthicknessbeff, mmM6 M8 M10 M12 M16 M20 M24 M30 M36JD1 25 4 100 6 900 8 600 10 400 13 800 17 300 20 700 25 900 31 10035 4 100 7 300 11 400 14 500 19 300 24 200 29 000 36 200 43 50040 4 100 7 300 11 400 16 400 22 100 27 600 33 100 41 400 49 70045 4 100 7 300 11 400 16 400 24 800 31 100 37 300 46 600 55 90070 4 100 7 300 11 400 16 400 29 100 45 500 58 000 72 500 86 90090 4 100 7 300 11 400 16 400 29 100 45 500 65 600 93 200 111 800105 4 100 7 300 11 400 16 400 29 100 45 500 65 600 102 500 130 400120 4 100 7 300 11 400 16 400 29 100 45 500 65 600 102 500 147 500JD2-JD5JD6 25 1700 2 200 2 800 3 300 4 400 5 500 6 600 8 300 9 90035 1900 3 100 3 900 4 600 6 200 7 700 9 200 11 600 13 90040 1900 3 400 4 400 5 300 7 000 8 800 10 600 13 200 15 800105 1900 3 400 5 300 7 600 13 500 21 100 27 700 34 700 41 600120 1900 3 400 5 300 7 600 13 500 21 100 30 400 39 600 47 500Capacity of Type 2 bolted connectionsCapacity 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 bearingstrength) larger than f p (unconfined bearing strength)Nd,j = n Nd,tbNd,j = φ k1k7n f pj AwAS1720.1 4.4.3.3
  17. 17. 7/05/1317Detailing bolted connectionsDistances measured centre-to-centre•  Minimum end distances – measured parallel tograin•  Minimum edge distances – measuredperpendicular to grain•  Spacing parallel to grain•  Spacing perpendicular to grainWashers•  Minimum size and thicknessVariations•  Coach screws•  Dowels•  Dowelled fin plates
  18. 18. 7/05/1318Fire•  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 residualsection 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 fireConnections in fire
  19. 19. 7/05/1319Problems 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 temperaturesStrategiesEnsure connections are not weakest link•  Make sure connections have higher fire ratings thanmembers•  Alternatives!  protect connections behind plasterboard!  place sacrificial timber between connections and the potentialfire – either plugs or plates!  use 100% timber connections eg timber dowels
  20. 20. 7/05/1320PlasterboardPlasterboard•  Connections are part of tested system•  Cover and protect the connection as though it istimber•  Care at corners, penetrations and junctions (usefire-resistant sealant – fire-grade flexible materialfilling gaps)•  Extra layers at connections ensure fasteners are notthe weakest link
  21. 21. 7/05/1321PlasterboardFire protection coverings:!  13 mm fire-grade plasterboard!  12 mm cellulose fire-reinforced cement sheeting complying withAS2908.2!  12 mm fibrous plaster reinforced with13 mm x 13 mm x 0.7 mm galvanised steel with mesh located notmore than 6 mm from the exposed face!  Other material equivalent to 13 mm fire-grade plasterboard!•  Protection by:o  surfaceprotection oro  embed fixingsunder plugs•  Other protectionmeasures need testdata to support theirusePlugs
  22. 22. 7/05/1322PlatesPlates
  23. 23. 7/05/1323Plates•  Thickness of the plate is sacrificial depth of timberfor charring•  Cover the connection as though it is timber•  Care at corners, penetrations and junctions (usefire-resistant sealant – fire-grade flexible materialfilling gaps)•  Extra layers at connections ensure fasteners are notthe weakest linkTimber dowels
  24. 24. 7/05/1324Timber dowels•  Substitute for steel (steel may soften in fire)•  Dowels char in same way and rate as memberConclusions•  Timber can be used for large, interestingcommercial and iconic structures•  Many different types of timber systems can be usedfor elegant structural solutions•  Connections are important in the realisation of thestructural scheme and are often part of the earlyconcept designs•  A lot can be achieved with the standard bolt ifused sensibly•  Fire protection by sacrificial timber or oversizing
  25. 25. 7/05/1325Other information•  Handbook 108-2013 (Standards Australia)•  Wood Solutions websitewww.woodsolutions.com.au•  Two-day UTas MasterclassPerth, 2 and 3 May, 2013AS1720 Timber Engineering Master Class April/May 2013

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