11/6/2016 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering K ANSAS ANSAS S TA TATE U N I V E R S I T Y Design of Timber Structures with Sawn and Engineered Wood Members Workshop By Don Phillippi, Ph.D., SE, Architect 1 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Outline AM Wood Frame Codes, Guidelines and Specifications Short history on the development of conventional wood • framing Benefits and drawbacks of conventional wood framing • American Wood Council’s National Design Specification • (NDS) for Wood Construction ASD – Allowable Stress Design • LRFD – Load and Resistance Factor Design • Wood framing provisions of the International Building Code • (IBC) and state and local building codes ASCE 7-10 load specifications • Project conception and material choices • 2 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Outline PM Wood Frame Design and Construction Techniques Design tools and techniques • Anchoring to concrete or masonry • Beams, posts and trusses • Connections • Roof framing choices • Fire resistance and safety considerations • Cross-laminated timber (CLT) • 3 1
11/6/2016 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Part 1 (AM Session) 4 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering First the Basics, Parts of a Tree (Breyer et al.) Heartwood – Older Inactive portion / provide strengths • Sapwood – Newer (contains both Active & Inactive), Stores • Food and Transports Water to Tree Cells The Closer the Annual Rings the Stronger the Wood • Nature’s “Composite” • Bark Heartwood Earlywood Sapwood Annual Ring Latewood 5 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Types of Wood Softwoods Narrow, needle like leaves • Evergreen (stay green all year) • Conifers (pine trees) • Examples: Hem-Fir, Douglas Fir-Larch, Southern Pine • Typically used in construction • Hardwoods Broadleaf • Deciduous (lose leaves in fall/winter) • Examples: Walnut, Ash, Maple, Balsawood (though soft) • Typically used for cabinets, flooring and paneling • 6 2
11/6/2016 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Sawn Member Sizes: 2" Nominal Size "Full Sawn" 2"x4" 2" 4" 31 Dressed Size 1-1/2"x3-1/2" Surfaced 4 Sides 11 2" "S4S" Nominal vs. "S4S" 2x4 Sawn Lumber 7 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Sawn Member Properties (examples): Standard Standard Area of Section Moment Area of Section Moment Nominal Dressed Nominal Dressed Section Modulus of Inertia Section Modulus of Inertia Size Size (S4S) Size Size (S4S) A S xx I xx A S xx I xx b x d b x d b x d b x d in. 2 in. 3 in. 4 in. 2 in. 3 in. 4 in. x in. in. x in. 2 x 4 1.5 x 3.5 5.25 3.06 5.359 6 x 6 5.5 x 5.5 30.25 27.73 76.26 2 x 6 1.5 x 5.5 8.25 7.56 20.80 6 x 8 5.5 x 7.5 41.25 51.56 193.4 2 x 8 1.5 x 7.25 10.88 13.14 47.63 6 x 10 5.5 x 9.5 52.25 82.73 393.0 2 x 10 1.5 x 9.25 13.88 21.39 98.93 6 x 12 5.5 x 11.5 63.25 121.2 697.1 2 x 12 1.5 x 11.25 16.88 31.64 178.0 6 x 14 5.5 x 13.5 74.25 167.1 1128 2 x 14 1.5 x 13.25 19.88 43.89 290.8 6 x 16 5.5 x 15.5 85.25 220.2 1707 4 x 4 3.5 x 3.5 12.25 7.15 12.51 6 x 18 5.5 x 17.5 96.25 280.7 2456 4 x 6 3.5 x 5.5 19.25 17.65 48.53 8 x 8 7.5 x 7.5 56.25 70.31 263.7 4 x 8 3.5 x 7.25 25.38 30.66 111.1 8 x 10 7.5 x 9.5 71.25 112.8 535.9 4 x 10 3.5 x 9.25 32.38 49.91 230.8 8 x 12 7.5 x 11.5 86.25 165.3 950.5 4 x 12 3.5 x 11.25 39.38 73.83 415.3 8 x 14 7.5 x 13.5 101.25 227.8 1538 4 x 14 3.5 x 13.25 46.38 102.41 678.5 8 x 16 7.5 x 15.5 116.25 300.3 2327 4 x 16 3.5 x 15.25 53.38 135.66 1034 8 x 18 7.5 x 17.5 131.25 382.8 3350 8 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Board Foot and Board Feet (bf): Units of Measurement – Board Feet Board Foot = nominal 1” x 12” (12in 2 per foot) • Example for a 2x6 one foot long: 2"(6") 2 6 x 1 bf 2 12 in Example for a 4x10 three feet long: 4"(10") 4 10 x 3 ft 10 bf 2 12 in 9 3
11/6/2016 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Moisture Content Percentage of water to oven dry weight: 100 moist weight oven dry weight MC x percent oven dry weight Seasoning MC Sawn Dry Lumber: 19% MC Sawn Green Lumber: 19% MC 16% Glue-laminated (normal): MC Glue-laminated (wet): 16% 10 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Specific Gravity and Unit Weight Specific Gravity g Often Given in Literature Unit Weight 62.4 pcf Member Weight (example Douglas Fir – Larch) Douglas Fir Larch 0.5(62.4 pcf ) 31.2 pcf CrossSectionalArea Member Weight (31.2 pcf ) plf 2 144 in Member Weight (2x6 Douglas Fir – Larch) 2 8.25 in 2 6 x plf (31.2 pcf ) 1.79 plf 2 144 in 11 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Wood Grades Quality determined by a Grading Agency Visual Grading (most common) • Closeness of grains • Number of defects in a wood member • Machine-Stress Grading • In addition to visual grading • Subjects members to stiffness/deflection checks • • Often used in: Engineered Members Prefabricated trusses Glue-laminated (glulam or GLB) beams Cross-laminated (CLT) members 12 4
11/6/2016 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Visual Grading Closeness of Grains in 3 inch dimension Free of Heart Center (FOHC) • Boxed Heart (Pith Present) • Types of Defects Knots • Checks – perpendicular to grains (partial penetration) • Shakes – parallel to grains in ends of members • Splits – measured parallel to sides of members • Warp (Cup, Crook or Twist) • 13 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Types of Grades (not all species have all grades) Dense Select Structural Select Structural No. 1 & Better No. 1 No. 2 No. 3 Stud Construction Standard Utility Also, Redwood has “Open Grain” as separate types 14 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Grading Agencies Western Woods Product Association (WWPA) West Coast Lumber Inspection Bureau (WCLIB) Southern Pine Inspection Bureau (SPIB) Northeastern Lumber Manufacturers Assocation (NELMA) Northern Softwood Lumber Bureau (NSLB) National Lumber Grades Authority (NLGA) Redwood Inspection Service (RIS) 15 5
11/6/2016 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Putting in All Together Grade Stamps Include: Mill Designation Grading Agency Species Identification Wood Grade Wood Grade Seasoning Mill Designation 12 STAND &BTR D R S-DRY FIR Species ID Grading Agency Seasoning (WWPA) Designation 16 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Outline AM Wood Frame Codes, Guidelines and Specifications Short history on the development of conventional wood • framing Benefits and drawbacks of conventional wood framing • American Wood Council’s National Design Specification • (NDS) for Wood Construction ASD – Allowable Stress Design • LRFD – Load and Resistance Factor Design • Wood framing provisions of the International Building Code • (IBC) and state and local building codes ASCE 7-10 load specifications • Project conception and material choices • 17 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Brief history: Timber framing (a.k.a. post & beam) Heavy timber • No nails used • Joined timber • Mortise and Tenon • Scarf Joint • Pegs used in later years • Highly skilled labor (artisans often “signed” joints) • 18 6
11/6/2016 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Early Example: Roman Framing Straight Sheathing • Flat Rafters • Square or Round Purlins • Purpose? Sheathing Holds Tile • Flat Rafters are Stable • Purlins are Stable • (Evelyn Simak) 19 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Timber Framing (Post & Beam): (Lueger) 20 Don Phillippi, Ph.D., SE, Architect Department of Architectural Engineering Mortise and Tenon Joint with Wooden Pegs: Joint in old French roof (DC) 21 7
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