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Engineered Wood Products

Engineered Wood Products. Paul Cooper Faculty of Forestry University of Toronto. Outline. What are engineered wood products? What are their advantages or benefits? Examples of EWP Some issues with EWP. Strands Oriented Strand Board Parallel strand lumber Parallam TM Veneer based

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Engineered Wood Products

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  1. Engineered Wood Products Paul Cooper Faculty of Forestry University of Toronto

  2. Outline • What are engineered wood products? • What are their advantages or benefits? • Examples of EWP • Some issues with EWP

  3. Strands Oriented Strand Board Parallel strand lumber ParallamTM Veneer based Plywood Laminated veneer lumber (LVL) Veneer overlaid products Lumber based Glued laminated timbers Trusses Edge glued products Combinations I-Joists Structurally Insulated Panels Fiber based Fiber reinforcement 1. What are Engineered Wood Products? Wood based products (usually composites) designed to meet application-specific performance requirements and to take best advantage of the structural properties of the different components

  4. EWP’s address some of wood’s disadvantages • Natural variability of wood – strength unpredictable, unreliable • Hygrosopicity and resulting dimensional instability _______________________________ • Biodegradable – vulnerable to decay • Combustible

  5. Benefits or Advantages • Efficient use of wood through “engineering” e.g., placing stronger and more uniform components in areas of higher stress • Stable, uniform & consistent • “Reliable” • Flexible with respect to shape and size • Value added products • Composite products - Take advantage of best properties of different materials

  6. Efficient use of wood, Stable Compression Tension Neutral axis – Shear only I-Beam is very efficient use of materials

  7. Strong and Consistent Optimize strength through • Engineered design • Put strongest components where stresses are highest • Configure for efficient properties • Randomization of defects to reduce variability or increase reliability

  8. Reliable

  9. Flexible with respect to shape and size, aesthetics

  10. More employment/m3 More value/m3 Generates value locally Smaller enterprises Lower or no tariffs/duties Value Added Benefits

  11. Take advantage of component properties Fibre Reinforced Polymer reinforced wood beams

  12. A. Strand Based EWP1. Oriented Strand Board (OSB) • EWP since selected geometry of strands and orientation of layers of strands - Improvement over the original “waferboard” • Special grades used for value-added engineered products such as I-joists and rim board • Main deficiency is thickness swelling and Concentrated Static Load resistance

  13. Reduced variability and increased reliability

  14. OSB - uses Sheathing Rimboard I-Joists

  15. 2. Parallel strand lumber (PSL) • Made from long narrow strands (from strander not veneer) • E.g., Aspen • Used for window joinery, headers…

  16. Parallel strand products3. Parallam ™ • Strips of waste veneer (1/2” X 1-2’) • Laid up in large molds • Phenol Formaldehyde Resin – Microwave cure • Mainly Douglas-fir and Southern pine • Extremely strong and reliable

  17. PARALLAM™

  18. B. Veneer products 1. Plywood • Flat panel built up of plies of veneer through bonding • Cross-laminated for uniform transverse strength and high dimensional stability Face Cross-bands Back Core

  19. Veneer

  20. Plywood

  21. 2. Laminated Veneer Lumber (LVL) – Poplar, Douglas-fir Southern pine etc.

  22. C. Lumber-based products1. Finger-joined lumber

  23. 2. Machine stress rated lumber (MSR)

  24. 3. Trusses

  25. 4. Glued laminated timbers

  26. AGO

  27. Combination Products1. Fibre Reinforced Polymer for Beams • Failure is usually on tension face • Reinforce glulam or solid timbers with small amounts (1% to 3% by volume) of FRP in tension • Doubles beam bending strength or reduces beam size or allow longer span • Can retrofit existing beams (e.g. in bridges)

  28. 2. I-JOISTS • Light • Strong • Long Spans • Easy to put wiring, plumbing etc. through the web

  29. 3. Structural Insulated Panels

  30. 4. Honey-comb, Sandwich productshttp://www.superhoneycomb.com/characteristics.htm

  31. E. Fiber Based EWP • Fillers and reinforcement such as natural fibers embedded in or bonded to a matrix (polymer, cement etc.) • Enhance properties while lowering cost • Both matrix and fibers maintain their identity but produce a combination of properties not achievable by one component alone. .

  32. Wood particle/fiber cement composites

  33. Some Issues • Perceived low durability (decay) • Issues with fire performance of some composites • Potential new applications and new developments • Design for tall wood buildings (6 story +) • “Massive components) • Earthquake stability, hurricane performance, fire, durability, dimensional stability • Nano-composites, agri-fiber composites, biomass based resins and adhesives

  34. Market trend? Tough time for all construction products • New home construction ↓ • Renovation ↑ ↓? • Commercial/residential ↑? • Infrastructure ↑?

  35. Thank you! “Spruce Goose” – Resin impregnated and molded Birch “Microlam”

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