CE 479: Design of Building Components and Systems Fall 2012 – J. Liu

1. CE 479: Design of Building Components and SystemsFall 2012 – J. Liu Wood Beams: Additional Components

2. Wood Beams: Additional Components • Lumber Roof and Floor Decking • Fabricated Wood Components • Structural Composite Lumber (SCL) • Laminated veneer lumber (LVL) • Parallel strand lumber (PSL) • Prefabricated wood I-joists • Light-frame wood trusses

3. Lumber Roof and Floor Decking • Lumber sheathing (1” nominal thickness) used to span between closely spaced roof / floor beams • Typically plywood and other panel products • To be discussed later • Timber decking used for longer spans • Solid decking • Laminated decking

4. Solid Decking Common sizes are 2 x 6, 3 x 6, 4 x 6 nominal Tongue-and-Groove (T&G) edges most common

5. Glued Laminated Decking • Fabricated from three or more individual laminations • Laminated decking also has T&G edge patterns • Variety of face finishes available http://www.lockdeck.com/

6. Solid / Laminated Decking • Essentially a series of parallel beams that span between floor or roof framing • Bending stresses / deflection criteria govern maximum loads • Spans range from 3 to 20 ft and more http://www.lockdeck.com/loadtables.html

7. Layup of Decking

8. Layup of Decking • Timber Construction Manual (TCM) gives bending and deflection coefficients for various types of layups • Used to calculate required thickness of decking • Also have allowable spans and load tables (IBC and TCM (by AITC))

9. Fabricated Wood Components • Includes glulam, plywood, etc. • Here, some fabricated wood elements used as beams in roof or floor systems • Many are proprietary products • Design criteria and material properties vary from manufacturer to manufacturer http://www.canadawooduk.org/wood-products-structural.php

10. Structural Composite Lumber (SCL) • Engineered lumber that is produced in a manufacturing plant • Usually a reconstituted wood product from much smaller pieces of wood (than used for glulam) • Thin pieces of wood (dried to low moisture content) glued together • Includes laminated veneer lumber (LVL) and parallel strand lumber (PSL) • Some requirements in NDS Section 8 (SCL)

11. Structural Composite Lumber (SCL) Front to back, Laminated Veneer Lumber, Laminated Strand Lumber, and Parallel Strand Lumber. http://www.structuremag.org/article.aspx?articleID=361

12. Typical Structural Composite Lumber Properties http://www.structuremag.org/article.aspx?articleID=361

13. Laminated Veneer Lumber (LVL) • Fabricated from veneer ranging between 1/10 and 1/6 inches • All veneers are laid up with wood fibers running in one direction, resulting in high reference design values • General fabrication process similar to that of glulam http://en.wikipedia.org/wiki/File:Laminated_Veneer_Lumber.png

14. Laminated Veneer Lumber (LVL) • Produced in boards or billets ranging from ¾ to 3-1/2 in thickness • May be 4 ft wide and 80 ft long (depends on manufacturer) • Billets then sawn into sizes as required for specific applications

15. Laminated Veneer Lumber (LVL) • Uses include beams, joists, headers, scaffold planking, tension laminations of glulams, flanges for prefabricated I-joists

16. Parallel Strand Lumber (PSL) and Laminated Strand Lumber (LSL) • PSL starts with sheet of veneer, which is clipped into narrow strands that are approximately ½ in wide and up to 8 ft long • LSL made from small-diameter trees; flaking machines are used to produce wood flakes approx. ½ in wide, 0.03 in thick, and 1 ft long http://www.apawood.org/level_b.cfm?content=prd_lvl_main

17. Parallel Strand Lumber (PSL) and Laminated Strand Lumber (LSL) • Both types glued and bonded together under pressure and heat • Billets of PSL are similar to those of LVL, but can be somewhat larger for PSL (e.g. 12 in wide, 17 in deep, 60 ft long) • Uses similar to that of LVL

18. Parallel Strand Lumber (PSL) http://www.structuremag.org/article.aspx?articleID=800

19. Prefabricated Wood I-Joists • Initially constructed with solid sawn lumber flanges and plywood webs • More recently use LVL for flanges and oriented strand board (OSB) for webs • Some requirements in NDS Section 7 Prefabricated Wood I-Joists

20. Prefabricated Wood I-Joists • Make efficient use of materials (like steel I-beams) • Relatively stiff • Can be used to span up to 40 or 50 ft, but most uses are for shorter spans • Relatively lightweight and easy to handle on site • Deep and slender, so follow manufacturer’s recommendations for bracing and blocking • Prefabricated metal hardware available for connections

21. Light-Frame Wood Trusses

22. Trusses http://rooftrussblog.com/prefabricated-roof-trusses/ http://eeref.engr.oregonstate.edu/Sectors/Industrial/Wood_Product_Manufacturing

23. Light-Frame Wood Trusses • Majority of residential wood structures, and some commercial/industrial buildings, use some form of light wood trusses • Common spans range up to 75 ft • Spacing is on order of 16 to 24 in o.c. for floors and up to 8 ft o.c. for roof systems • Information on proper handling, bracing during construction, etc., from individual truss manufacturers

24. Light-Frame Wood Trusses From Canadian Wood Council

26. Roof Truss Layout

27. Trusses C01 – Common Truss M04 – Mono Truss M03 – Mono Truss

28. Truss Specifications