Transcript
Applications for Wood-Plastic Composites – Beyond Deck Boards Page 1 Applications for Wood-Plastic Composites – Beyond Deck Boards Don Bender, Professor Michael Wolcott, Professor Dan Dolan, Professor Page 2 Presentation Outline ∎ Trends in building construction and materials ∎ Current applications of WPCs ∎ Future applications ∎ Technical challenges Page 3 Trends in Low-Rise Construction ∎ Increased design complexity ∎ Wind and seismic ∎ Product support ∎ Emphasis on structural “systems” ∎ Multiple materials ∎ Engineer the interfaces ∎ Focus on durability and environment ∎ Decreased skill in workforce Page 4 Treated Lumber Trends ∎ 7.2 billion board feet of PPT lumber in 2002 ∎ Phase out of CCA ∎ Cost, efficacy and corrosion questions with replacement chemicals ∎ Opportunities for organic treatments and wood-plastic composites Page 5 Wood Composite Beams – Lessons Learned ∎ Identified performance requirements ∎ Developed new composites and efficient structural shapes (I- beam) ∎ Built on existing codes and standards for timber ∎ Gained market share through: ∎Performance and consistency ∎Educating engineers & architects ∎Codes & standards development ∎Not by offering a cheaper alternative to lumber! Page 6 Presentation Outline ∎ Trends in building construction and materials ∎Current applications of WPCs ∎ Future applications ∎ Technical challenges Page 7 Current Situation Most current wood-plastic composite applications have modest structural requirements ∎ Residential deck boards ∎ Rails and balusters ∎ Ornamental pieces ∎ Wearing surfaces ∎ Window lineals ∎ Door components Page 8 Substitution for PPT Lumber and Timber ∎ Playground structures ∎ Docks and shoreline retaining walls ∎ Fencing ∎ Landscaping features ∎ Post-frame buildings Page 9 Treated Wood vs. WPC’s Treated Wood ∎ Advantages ∎ Light weight ∎ Slip resistant ∎ Low heat retention ∎ Fire ∎ Low initial cost ∎ Disadvantages ∎ Leaching chemicals ∎ Fastener corrosion ∎ Degradation ∎ Dimensional stability ∎ Requires regular maintenance WPC’s ∎ Advantages ∎ Decay and insect resistant ∎ Water repellency ∎ Uniform dimensions ∎ Low maintenance ∎ Disadvantages ∎ Dense ∎ Heat retention ∎ Flame spread ∎ Thermal expansion ∎ High initial cost Page 10 Presentation Outline ∎ Trends in building construction and materials ∎ Current applications of WPCs ∎Future applications ∎ Technical challenges Page 11 Deck Supporting Elements “More injuries are associated with deck failures than all other wood building components and loading cases combined!” … Woeste and Loferski, Virginia Tech Univ, 2004 Page 12 Why Do Decks and Balconies Collapse? ∎ Deck-to-house connection ∎ Deteriorated wood (band joist, deck ledger, rail, post) ∎ Construction defects ∎ Deficient design ∎ Inadequate code enforcement Page 13 Engineered Deck System ∎ The problem is at the interface! ∎ Structural system – engineered, tested, technology transfer ∎ Redundancy (for durability and structural safety) ∎ Formulations to resist fire, biodegradation, weatherability ∎ Constructability – “idiot proof” ∎ Easy to modify and customize Page 14 Building Envelope Applications ∎ Siding ∎ Support for fire resistant panels ∎ Doors, windows and associated framing ∎ Connector details Page 15 Demonstration Building at WSU Page 16 Possibilities for Siding Applications Page 17 Foundation isolation element Page 18 Applications to Reinforce and Connect ∎ Sill plates ∎ Inter-story connectivity ∎ Frames to restore capacity of shear walls with openings ∎ Energy dissipating features to resist seismic Page 19 High-Moisture Interior Applications ∎ Backer board for tile ∎ Bathroom and kitchen countertops and cabinets ∎ Furniture ∎ Molding and trim Page 20 Rhode Island Demonstration Project Deck Loads ∎ Uniform Load ∎600 psf ∎ Point Load ∎Forklift single wheel load ∎18,000 lb Geometry ∎ 4 x 6 in deck boards ∎ Supported 2 ft o.c. Page 21 PORT HUENEME: Chock Installation ∎ Low Load Demand ∎ HDPE Formulation ∎ Flange/Web Design ∎ Foam/High Density ∎ Co-Extruded ∎ Modular Design ∎ 4x12 inch ∎ Post Assembly – 12x12 ∎ Feedback ∎ Machining Excellent ∎ Assembly Floats! Page 22 Other Potential Applications ∎ Don’t restrict your vision to residential construction ∎ What about commercial and industrial buildings? ∎ Transportation structures ∎ Other ∎ Poles and cross arms ∎ Sound barriers ∎ Shipping containers Page 23 Presentation Outline ∎ Trends in building construction and materials ∎ Current applications of WPCs ∎ Intermediate-term applications ∎ Long-term applications ∎Technical challenges Page 24 Technical Challenges for Engineered WPCs ∎ Fire resistance ∎ Stiffness and creep ∎ Weatherability ∎ Standards and coverage in codes ∎ Education of engineers, architects, and builders Page 25 Fire Resistance ∎ Identify important properties – ignition temps, heat release rates, flame spread, smoke development ∎ Develop appropriate test methods and levels of performance ∎ Opportunity to differentiate ∎ Address technical issues before fire marshals decide for you! Wildland Urban Interface Page 26 ∎ 16 min. ∎ Gap combustion Class C Burning Brand Cedar 2x6 26 Page 27 ∎ 20 min. ∎ 20 min. ∎ Bottom Plastic Lumber 27 Page 28 WPC 5 ∎ 20 Min. ∎ 60 Min. 28 Page 29 STRUCTURAL DESIGN ∎ NDS Timber Design Code ∎ Assess Structure and Loads ∎ Compute Component Stresses ∎ Compare to Limit States Design Values F b - Bending F v - Shear F t - Tension F c - Compression F e - Connector Bearing E - Bending Stiffness Page 30 DESIGN VALUE ASSIGNMENT t m a X CCCB F ∙ ∙ ∙ = Variability ( ) COV k xB ∙ - = 1 ADJUSTMENT LOAD ENVIRONMENT Page 31 CHARACTERISTIC VALUE - B Material Fb Fv Ft Fc Fc Fe E (psi) (psi) (psi) (psi) (psi) (psi) (ksi) WPC PVC 3242 1719 2512 5586 7184 18600 754 HDPE 1254 823 861 1682 3093 4960 359 PP 5059 2271 1567 7356 --- 12268 724 2x8 No.1 Hem-Fir 1170 150 813 1418 405 2950 1500 D. Fir-Larch 1200 180 878 1575 625 3650 1700 SPF 1050 135 585 1208 425 2850 1400 So. Pine 1250 175 675 1600 565 4200 1700 2x8 No.2 Hem-Fir 1020 150 683 1365 405 2950 1300 D. Fir-Larch 1080 180 748 1418 625 3650 1600 SPF 1050 135 585 1208 425 2850 1400 So. Pine 975 175 550 1450 565 4200 1600 Page 32 Cm 0.0 0.2 0.4 0.6 0.8 1.0 Wood HDPE+MAPE HDPE Ca 0.0 0.1 0.2 0.3 0.4 0.5 Wood PVC HDPE Ct 0.0 0.2 0.4 0.6 0.8 1.0 Wood HDPE-1 HDPE-2 PERFORMANCE ADJUSTMENTS t m a X CCCB F ∙ ∙ ∙ = ld a f C ∙ = 3.1 1 Safety & Load Duration Moisture Adjustment Temperature Adjustment Page 33 Bolted Connection Design ∎ Modified timber connection design methodology for solid and hollow WPC members ∎ Validated design with full-size tests Page 34 Summary ∎ Many applications exist using current WPC technology ∎ Improvements in stiffness, creep, fire and weatherability will open more applications ∎ Work is needed in codes and standards (make sure your interests are represented) ∎ Design methodologies are needed (piggyback on an existing design format) ∎ Education of engineers, architects, and other users is crucial
Original URL
http://www.woodsymposium.wsu.edu/Proceedings05/Session%20IV%20pdf%20files/Bender.pdf
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