TIMBER STRUCTURES AND BUILDING …...Dowel type timber joints Connector joints Truss plate joints 7...

KIT – University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association

TIMBER STRUCTURES AND BUILDING CONSTRUCTION

www.kit.edu

Connections for timber structuresHans J. Blass

Timber Structures and Building Construction2 09.08.2010 Hans J. Blass

Timber bridge in Sneek, NL


Timber joints

Glued jointsJoints with mechanical fastenersCarpenter joints

Glued joint


Timber joints

Glued jointsJoints with mechanical fastenersCarpenter joints

Joint with mechanical

fasteners


Carpenter joint


Joints with mechanical fasteners

Dowel type timber jointsConnector jointsTruss plate joints


Connector joint


Johansen‘s model


Plug shear


Splitting

a1

a3

a4a2


Reinforcement using screws with continuous thread


Screws stop crack growth


Screws loaded in shear

0,5·F 0,5·F

F


Inclination of fastener axis


Truss action

0,5·F 0,5·F

F


Fax

Fc,90

F0

Ffr

Truss action


Bolted steel connections in shear

Source: Project KI-Smile


Truss connection

Photo: Wiehag


Frankfurter Messehalle 11

Photo: Atlas Copco


Inclined screws in steel-to-timber joints

Photo: Atlas Copco


Connection test Stuttgart University

Ultimate load per shear plane:Test 1: FU = 6200 kNTest 2: FU = 6600 kN

Photo: Universität Stuttgart


Failure mode: screw tensile failure

Photo: Universität Stuttgart Photo: Universität Stuttgart


Screws parallel to member axis

A

B

B

A

glulam

glulam

CLT

A-AB-B


Glulam

CLT

Threaded rods


Screws parallel to member axis

A A

B

BB-B

A-A

glulam

CLT


Axially loaded screws

Preliminary tests led to timber splitting or screw withdrawal after timber reinforcement


Timber is anisotropic

Avoid perpendicular to the grain stressesDesign for low strength and stiffness perpendicular to the grainReinforcement


Shear failure parallel to grain


Fax

Fax

τ σc,90

σc,90

Shear reinforcement


Crack


Curved and pitched cambered beams


Tensile failure perp. to grain


Curved and pitched cambered beams


Notched beam supports


Reinforcement with screws

A

A-A

fully threaded screws

A


Compression perp. to grain

Photo: Kreuzinger


Fc,90

σc,90 = fc,90

Compression perp. to grain


Fc,90

σc,90 < fc,90


0

50

100

150

200

250

300

0 1 2 3 4 5

displacement in mm

load

R90

in k

N

non-reinforced

8 x 400 mm 8 x 260 mm

7,5 x 180 mm

Bottom view

Bottom view

Reinforcement using screws

Timber Structures and Building Construction47 09.08.2010 Hans J. BlassThank you very much for your attention !

TIMBER STRUCTURES AND BUILDING …...Dowel type timber joints Connector joints Truss plate joints 7...

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Transcript of TIMBER STRUCTURES AND BUILDING …...Dowel type timber joints Connector joints Truss plate joints 7...