modern timber connections - wood works

12/10/2013

1

Modern Timber Connections

by

Maik Gehloff, DI (FH), MASc

Gehloff Consulting Inc.

at

Toronto Wood Solutions Fair

Metro Convention Centre, Toronto, ON

Tuesday, November 12th, 2013

Copyright Materials

This presentation is protected by US and International Copyright laws.

Reproduction, distribution, display and use of the presentation

without written permission of the speaker is prohibited.

© Gehloff Consulting Inc. 2013

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Program Education Credit Information

The Canadian Wood Council is a Registered Provider with the American Institute of

Architects. This course meets Continuing Education System requirements for one

Learning Unit. Credit earned on completion of this program will be reported to CES

Records for AIA members who provided their member number during the online

registration. This course also qualifies as Structured Learning with OAA. Certificates

of Completion for OAA members, and anyone else who indicated they wanted a

certificate, will be emailed after the event to those who requested them during the

registration process. We will also report participation to the Engineering Institute of

Canada on behalf of any engineers who requested their participation be recorded.

This program is registered with the AIA/CES for continuing professional education.

As such, it does not include content that may be deemed or construed to be an

approval or endorsement by the AIA of any material of construction or any method or

manner of handling, using, distributing, or dealing in any material or product. The

same is true for the OAA and EIC. Questions related to specific materials, methods,

and services will be addressed at the conclusion of this presentation.

4

Content

• Introduction • Self-tapping (Modern) Wood Screws (STS)

• Introduction • Applications

• as primary connector • as part of a connection system • as reinforcement

• Performance/Design(Guidance)

• Connection Design


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5

Content







6

Introduction

The material WOOD itself

The Good;

• renewable and sustainable

• beautiful, warm

• easy to work with

• strong (weight to strength ratio)

The not so Good;

• hygroscopic, none homogeneous, un-isotropic

• inherent weakness in longitudinal shear

tension perp. to grain

compression perp.


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7

Introduction

Common connectors

• Bolts

• Lag screws / Lag bolts

• Threaded rods

• Screws

• Nails / Spikes

• Pegs

• Shear plates and split rings

• Custom steel parts

• Off the shelf parts


8

Introduction

Source: CWC


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9

Introduction

Common connectors

• Bolts

• Lag screws / Lag bolts

• Threaded rods

• Screws

• Nails / Spikes

• Pegs

• Shear plates and split rings

• Custom steel parts

• Off the shelf parts


10

Introduction

Source: CWC

Source: DIN


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11

Introduction

Source: Colling


12

Introduction

Source: CWC


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13

Content







14

STS - Introduction

Self-tapping screws? (as supposed to self-drilling?) Self-drilling: self-drilling screws are for metal only and do not work (well) in wood, remove material Self-tapping: self-tapping screws work well in most materials, shaft designed to cut threads into the material as they are driven in


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15

STS - Introduction

Why self-tapping screw?

1) Long threads creates high friction and drive-in torques pre-tapping reduces that friction and drive-in torque

2) Pre-tapping hole with intended diameter

Eliminates risk of oversized holes and reduces splitting


16

STS - Introduction

Self-tapping screws come in many different varieties

Source: Blass


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STS - Introduction

small core diameter

• larger wings

• more bite

• less splitting

improved shank cutter

• reduced clogging

• friction reduction

• allows shrinkage and swelling

hardened steel High tensile strength (>800 N/mm²)


18

STS - Introduction

Why self-tapping screws?

• High tension strenght of the steel

• High withdrawal resistance

• Easy to apply (drill tip)

• Economic use in timber joints and reinforcements


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19

STS - Introduction

Shear AND

Withdrawal

Source: Blass


20

STS - Introduction

Source: Blass


Source: Colling

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21

STS - Introduction

Failure modes

Source: Blass


22

STS - Introduction

Source: flickr.com Source: brickset.com

≠ Source: MyTiCon


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23

Content







24

STS – Applications (as primary fastener)

Source: Blass


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25


Source: SFS / HECO


26


Source: Colling


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27


Source: HECO


28


Source: SFS


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29


Source: UBC - TEAM


30


Source: UBC - TEAM


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31


Source: Würth / SWG Gehloff Consulting Inc.

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30m high 77m free span + 12m cantilevers 12 x 115m long truss, 6.7m high 2,600 m³ glulam beams

Gehloff Consulting Inc. Source: Wiehag

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33


Tension in lower chord: Fd = 3,500 kN, ultimate load: 13 MN Connection: 4 x 216 STS Ø 8 mm x 800 mm without pre-drilling


Source: Wiehag

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Content







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STS – Applications (as part of a connection system)

Source: SIGHA


37


Source: SIGHA


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38


Source: KNAPP Gehloff Consulting Inc.

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Source: Bohrenkaemper


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40


Source: PITZL


41


Source: Sherpa / PITZL


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Source: SFS


43


Source: SWG Gehloff Consulting Inc.

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Content







45

STS – Applications (as reinforcement)

Source: Blass

x

st,90

ft,90


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46


Source: Blass

Threaded rod or similar

glued on plywood or similar


47


Source: Blass

50260

880

A A

140

Schnitt A - A

Vollgewinde-schrauben10 x 600

280

320

280

60

40

40


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48


Source: Bejtka Gehloff Consulting Inc.

49


Source: UBC - TEAM


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50


Source: Blass


51


Source: Blass

Rd

Rd

hd

Rd

6·R

a1

F

0

10

20

30

40

50

60

0 3 6 9 12 15

Verschiebung d in mm

La

st

R in

kN


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52


Source: Blass

Rd

Rd

Rd

Rd

1a

h8·Rd

F

0

10

20

30

40

50

60

0 3 6 9 12 15


Last

R i

n k

N


53


Source: Blass

Rd

Rd

Rd

Rd

1a

h8·Rd

0

10

20

30

40

50

60

0 3 6 9 12 15


Last

R i

n k

N

F


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54


Source: Blass

Rd

Rd

Rd

Rd

1a

h8·Rd

0

10

20

30

40

50

60

0 3 6 9 12 15


La

st

R i

n k

N

F


55


Source: Blass

Rd

Rd

Rd

Rd

1a

h8·Rd

F


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56


Source: Blass


57


Source: UBC - TEAM

Source: Tannert


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Source: Blass

Source: UBC - TEAM


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Content







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Fastener in tension/withdrawal

DIN 1052:2004-08 (Germany) Eurocode (EC) 5 : 2010

2

.222

.1

. ;

cos3

4sin

min kK

efK

Kax dfldf

R

26

,1 10 kKf

8.0

22

,

,,sincos2.1

a

kefkaxef

Rkax

ldfnF

= 80 (for STS’s)

STS – Performance/Design


61

Fastener in tension/withdrawal

DIN 1052:2004-08 (Germany) Eurocode (EC) 5 : 2010

2

.222

.1

. ;

cos3

4sin

min kK

efK

Kax dfldf

R

26

,1 10 kKf

8.0

22

,

,,sincos2.1

a

kefkaxef

Rkax

ldfnF

= 80 (for STS’s)



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62


• Fastener in shear: use CSA O86 (lag screw section) considering design parameters of chosen screw

• Fastener in tension: NO suitable guidance given in CSA- O86 use EC5 (EN1995)

• EN1995 (EC5): Standardization for all European countries by replacing the old national standards

• On a national level, national standards are still in place as “National Application Documents”

• Calculate the respective force components according to local codes or international codes if needed

Source: CSA-O86


63


8.0

22

,

,,sincos2.1

a

kefkaxef

Rkax

ldfnF

8.0

2

,,,

a

khkheadefRkax dfnF

ktensefRkt fnF ,,

Eurocode (EC) 5 : 2010


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64


8.0

22

,

,,sincos2.1

a

kefkaxef

Rkax

ldfnF

8.0

2

,,,

a

khkheadefRkax dfnF

ktensefRkt fnF ,,



65


8.0

22

,

,,sincos2.1

a

kefkaxef

Rkax

ldfnF

8.0

2

,,,

a

khkheadefRkax dfnF

ktensefRkt fnF ,,



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66


Source: Colling


67


Source: Colling

Source: UBC - TEAM


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68


2 3

t,90,d 90,dF 1 3 2 F

2 3

t,90,d dF 1,3 V 3 1 2 1

Source: Bejtka Gehloff Consulting Inc.

69


Source: Bejtka

2

d d d dt,90,d 2

r

V h h MF 3 0,008

4 h h h

s

t,90,d 1

t,90,d

b a2F

3 n


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70


8.0

22

,

,,sincos2.1

a

kefkaxef

Rkax

ldfnF

8.0

2

,,,

a

khkheadefRkax dfnF

ktensefRkt fnF ,,


71



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72


Source: Würth / SWG


73


Source: Ernst Gehloff Consulting Inc.

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Content







75

Connection Design

Material: Douglas-fir (solid sawn) Dimensions: both members 8 x 8 (7.5 x 7.5) Screws: (6) 8.5 x 215mm HECO TOPIX-CC

8.0

22

,

,,sincos2.1

a

kefkaxef

Rkax

ldfnF

8.0

2

,,,

a

khkheadefRkax dfnF

ktensefRkt fnF ,,


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76

Connection Design

Material: Douglas-fir (solid sawn) Dimensions: both members 8 x 8 (7.5 x 7.5) Screws: (6) 8.5 x 215mm HECO TOPIX-CC

8.0

22

,

,,sincos2.1

a

kefkaxef

Rkax

ldfnF

8.0

2

,,,

a

khkheadefRkax dfnF

ktensefRkt fnF ,,


77

Connection Design

Source: HECO Gehloff Consulting Inc.

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Connection Design

Material: Douglas-fir (solid sawn) density 0.49 !!! Dimensions: both members 8 x 8 (7.5 x 7.5) Screws: (6) 8.5 x 215mm HECO TOPIX-CC head-size ~ 9mm diameter d 8mm lef 215mm – 5mm = 210mm fax,k 12.5 N/mm2 12.5 Mpa ftens,k 18.0 kN nef 6 (why?)

α 45° (why?)

ρa 350 kg/m3

8.0

22

,

,,sincos2.1

a

kefkaxef

Rkax

ldfnF

ktensefRkt fnF ,, Gehloff Consulting Inc.

79

Connection Design

ρk,0% = (G *1000) * 0.84

Source: CSA O86


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80

Connection Design

ρk,0% = (G *1000) * 0.84

or

with

GM = (ρk,0% /1000) and M = 12%

ρk = 1000 * ρk,0% * (1+M/100)

ρk = ([G *1000] * 0.84)* (1+M/100)

Source: Wood Handbook


81

Connection Design

Material: Douglas-fir (solid sawn) density ρk ~ 460 kg/m3 Dimensions: both members 8 x 8 (7.5 x 7.5) Screws: (6) 8.5 x 215mm HECO TOPIX-CC head-size ~ 5mm diameter d 8mm lef 215mm - 5mm = 210mm fax,k 12.5 N/mm2 12.5 Mpa ftens,k 18.0 kN nef 6 (why?)

α 45° (why?)

ρa 350 kg/m3

8.0

22

,

,,sincos2.1

a

kefkaxef

Rkax

ldfnF

ktensefRkt fnF ,, Gehloff Consulting Inc.

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82

Connection Design

mod

,,

,, kF

FM

Rkax

dax

= 1.3 connections 𝛾𝑀

Source: EC5 Gehloff Consulting Inc.

This concludes the:

American Institute of Architects

Ontario Association of Architects

Engineering Institute of Canada

Continuing Education Systems Program

Modern Timber Connections

Gehloff Consulting Inc.,

[email protected] | +1 (604) 200-0242

Questions/ Comments?

mailto:[email protected]

