ttf cpd no1 engineered timber - an overview (for distribution)
TRANSCRIPT
Engineered Timber – An overview
Deb Turnbull
4 October 2012
www.napier.ac.uk/isc
The need for re-engineering
Timber composites - what are they?
Basic information - Glulam, PSL, LSL, LVL
Massive timber - Brettstapel- CLT
Timber I-beams
Timber trusses - Carpentry- Plate connectors- Metal webs
Timber with other materials - Steel- Cement/concrete- Insulation
Timber frame
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Resource - Length- Cross sections
Properties - Structural performance- Species
The need for Re-engineering
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Page 4
Timber Composites
CTS Bridges
Welsh Oak Frame
Dimensional stability- moisture content- cross laminations
Structural performance- more homogenous material- increased lengths
Greater use of resource
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Timber Composites
Veneers
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Timber Composites
PlanksGlulam
Massive Timber
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Timber Composites
Flakes
Laminated Strand Lumber(LSL)
Oriented Strand Board(OSB)
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Timber Composites
Chips
Saw dust Fibreboards
Chipboard
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Timber Replacement
Longer spans
Higher performance
Appearance
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Glulam
I-joistsBox
beams
Components and systems
trusseswalls
and floor panels
LVLPlywood
OSBFibreboard
PSL
Sawn timber CLT
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GlulamManufacture
Stock sizes - 90 to 265 wide and 180 to 2050- square and circular sections available
Bespoke - curved, tapered, portal frames
Species - Spruce is usual, pine and larch also available- Other species have been tried including UK grown
Design - fabricators often have in-house design capability- manufacturers have free software- connections need special consideration
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Glulam uses
Beams, Columns
Portal Frames
Space Frames
Geodesic structures
Scottish parliament, Cowley Timberwork Strawberry Lodge, Chiswick, Axis Timber
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Acetylated timber in glulam beams
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Parallel Strand Lumber (PSL) &Laminated Strand Lumber (LSL)
Only one manufacturer – Weyerhaeuser (was Trus Joist)No longer available
Sizes - stock sizes- special sizes for I-joist systems
Design - manufacturers have free software- connections
Uses - in UK, beams and columns in timber frames
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Laminated Veneer Lumber (LVL)
Typical stock sizes - thickness 27, 33, 39, 45, 51, 57, 63, 69, 75- width 200 to 900
Spans - Floors up to 9m- Roofs up to 18m
Design - manufacturers have free software
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LVL uses
Rim boards in timber frame
Beams, Columns
Portal Frames
Space Frames
Geodesic structures
Stressed skin panels
Edinburgh Napier University, Cowley Timberwork
Kerto Q monocoque panels, Cowley Timberwork
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Massive Timber
Brettstapel - nailed- dowelled
Cross Laminated Timber- glued- dowelled- interlocking
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Brettstapel
Can use lower grade timber
Nailed or all timber product
Used for walls and floors
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Manufacture
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Higher levels of automation
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Fabrication into panels
2.5 wide and up 18.5m long
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Structural design
Flatwise
Stiffness - Emean for all stiffness calculations
Shear deformations not so significant due to span to depth ratio
Material safety factor, k mod x (strength property)ϒm
Connections need careful thought
Edgewise
Racking
Bending
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Panel sizes and spans
Typical load span table for timber with MOE of 11,000 N/mm2 Grade C24
LoadThickness(mm)
4.3
8.6
6.0
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Building performance
Airtightness - Relies on additional layer – typically OSB
Thermal performance- 100mm thick panel of 500 kg/m3 U=0.13 W/mK
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External wall make-upsPanel profiles
Directly applied plasters
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Brettstapel
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Cross Laminated Timber
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Typical lay-ups
Panel thickness Layer thickness
51 Metsä 17, 17, 17100 BinderHolz 37, 26, 37126 StoraEnso 42, 42, 4285 Metsä 17, 17, 17, 17, 17147 BinderHolz 41, 22, 21, 22, 41200 KLH 40, 40, 40, 40, 40
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CLT Benefits
Airtight - if edges glued
Don’t generally need lintels
Speed on site with large panels
Good replacement for reinforced concrete- 6 times lighter- 1/3 the thickness for similar span
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Pag 31
Waugh Thistleton Architects BRE Ravenscraig Visitor Centre
Hackney Academy, Eurban
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Use of EC5 – multiple connected layers and Appendix B
Fire – charring rate
Structural design
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Preliminary sizing
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Manufacturers design software
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Other Guidance
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Dowelled cross laminated timber
TechnoWoodHolz100Nur HolzThoma
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Timber Trusses
Cheadle Hume, Cowley Timberwork
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with steel
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UK Sitka spruce Trusses
Compared to above using plywood gussets
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Timber I-Beams
CTS Bridges
Welsh Oak Frame
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Timber I joists
CTS Bridges
Welsh Oak Frame
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Special uses with connectors
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Timber in Combination with other materials
Steel
Concrete
Insulation
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Timber in Combination with Steel
Flitch beams Bolted Impact nailed
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CTS Bridges Forestry Commission
Mechlam bridges Stress laminated bridges
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Page 46
With concrete
Acoustics
Thermal mass
Longer spans than timber alone
Composite
Non-composite
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Welsh Oak Frame
Non-composite systems
With I-joist floors
Manufacturers linked with screed suppliers
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Timber concrete - composite action
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Page 49
CTS Bridges
Welsh Oak Frame
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01 October 2010
Kaufmann Oberholzer, CH
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With insulation
Panels
Beams
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Structural Insulated Panels - SIPs
Sheathing layers
Bonded insulation – injected PUR foam- glued EPS
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Joints
- splines-thinner full sections
Fixings- Some straight into OSB
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01 October 2010
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Composite Insulated Beams (CIBs)
Increased bearing capacity - 18-30%
Heat loss reduced by 56-86%
Most efficient – Box beams with timber or LVL flanges
Beams and CIBs had increased shear and bending strength over I-joists
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Page 57
Timber Frame
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Can incorporate many forms of engineered timber
- Improved joists, I joists and timber trusses for walls and floors- For replacement of steel for purlins and rafters- Cassettes- Acetylated timber ground beams
Thank-you