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Connections

Connections. Joints. Overview over joints in timber constructions. Carpentry joints Metal fasteners. End grain skew notch:. Tenon:. Low load-carrying capacites, Manufacturing expensive, expect CAM is used. Mortise and tenon joint:. Metal fasteners:. Nails .

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Connections

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  1. Connections Design of Timber Structures

  2. Joints Overview over joints in timber constructions • Carpentry joints • Metal fasteners Design of Timber Structures

  3. End grain skew notch: Tenon: Low load-carrying capacites, Manufacturing expensive, expect CAM is used. Design of Timber Structures

  4. Mortise and tenon joint: Design of Timber Structures

  5. Metal fasteners: Nails Dowels Bolts Design of Timber Structures

  6. Dowels Fit-Bolts Rope effect Higher Load-carrying capacity Design of Timber Structures

  7. Design of Timber Structures

  8. l d t1 t2 Start values - Thickness of timber / wood based panel - Penetration length of fastener - Diameter of connector - Embedment strength of material (function of density) - Yield moment of fastener

  9. Start values General: • Embedment strength related to density  better exploitation of material • For fasteners with  > 8mmthe relationship between load bearing capacity and angle between force and grain direction has to be taken into account (not valid for nails with   8mm) • For screws with  < 8mm the rules for nails and with   8mm the rules for bolts apply • Reduction of load bearing capacity for many fasteners in a row with exception of nails

  10. Start values • Take into account minimum edge and space distances of fasteners General: • If the force direction deviates from the grain direction, tension perp. to grain has to be taken into account • The slip modulus of a connection for the ultimate limit state, Ku ,skould be taken as: Ku = 2/3 *Kser

  11. Parallel acting of different fasteners Different slip moduli!!! No parallel acting of glue and fasteners!

  12. Reduction of load bearing capacity If alternate medium and long term actions occur (tension Ft and compression Fc) the calculation should be done by Ft,d + 0,5*Fc,d Fc,d + 0,5*Ft,d

  13. Weakening of cross section • Reduction of cross section has to be taken into account. Exceptions • Non-predrilled nails up to 6 mm diameter • Holes in the compression area, if they are filled with a material with a MOE equal or higher of the timber • Cross section reduction shall be taken into account in an area of min a/2 a = minimum spacing of fasteners

  14. Lateral load carrying capacity • Different rules for: • Fasteners in single- and double-shear in timber-to-timber and timber-to-panel connections • Fasteners in single- and double-shear in timber-to-steel connections with thin and thick steel plates (thin: t  0,5 d) • Multiple shear plane connections

  15. F F Thin and thick steel plates • Single shear plane timber-steel-connection Thick steel plate Thin steel plate  Partly cantilevered dowel;  Increased load- bearing capacity  Twisting dowel

  16. Validity • Rules apply for nails, staples, bolts, dowels and screws • The characteristic value Fv,Rk applies per fastener and per shear plane

  17. timber - timber/panel-connections • Start values: t1 , t2 Thickness of timber/panel or penetration depth fh,i,k , Characteristic embedment strength fh,1, / fh,2,k  d Fastener diameter My,k Characteristic fastener yield moment

  18. timber - timber/panel-connections • Single shear plane– calculation of Fv,k Embedment strength failure

  19. timber - timber/panel-connections • Single shear plane – calculation of Fv,k Fastener yield moment and embedment strength failure

  20. timber - timber/panel-connections • Calculation of design value: with M = 1,3 for connections and if two different materials are involved (see clause 2.3.2.1)

  21. Multiple shear plane connections ta t ti t ta Steel plate bolt 1 2 3 4 4 shear planes B A A B

  22. 1)Shear plane(s) A 2)Shear plane(s) B B A A B Multiple shear plane connections ta t ti t ta B A A B

  23. 1)Shear plane(s) A exterior shear plane calculation as a double shear plane connection with inner steel plate

  24. 2) shear plane(s) B Interior shear plane thick steel plates calculation as double shear plane connection with exterior steel plate

  25. F F Thin steel plate Interior shear plane  The exterior timber creates the same effect as a thick steel plate, independent from the real thickness of the plate

  26. Examples for bolt resp. dowel joints: Design of Timber Structures

  27. Dowel-type fasteners: Load-carrying capacity Rd for connections with solid timber C 24 with steel dowels S 235, per shear plane Service class 2, medium term action Design of Timber Structures

  28. Nail plates / other connectors Nail plate System Greim (thin steel plates – nail connection Multi-dowel (nail) clamp

  29. Connectors Split ring and tooth plate connectors Type A1, B1 C1, C2, C 19, C 11 Design of Timber Structures

  30. Split ring and tooth plate connectors Type A1, B1 C1, C2, C 19, C 11 t t Design of Timber Structures

  31. Split ring and tooth plate connectors Diameter dc in mm Design resistance per shear plane Service class 2, medium term action Design of Timber Structures

  32. Screws and staples staple

  33. Connections with screws According to EC 5 or DIN Screws with type Approval Without Predrilling www.spax.com www.sfsintec.biz Design of Timber Structures

  34. F Subjected to shear 0,5·F 0,5·F Design of Timber Structures

  35. Subjected to shearStrong rope effect higher design resistance Design of Timber Structures

  36. Fixing system WT of SFSintec: Design of Timber Structures

  37. Design of Timber Structures

  38. Fixing system WT of SFSintec: Examples for use: Design of Timber Structures

  39. Fixing system WT of SFSintec: Design of Timber Structures

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