The document describes innovative structural sections made from roundwood including wood I-beams and zig-zag decking. Wood I-beams can be up to 48 inches in size and utilize over 90% of roundwood material. They are 4.5-5 times stronger than solid roundwood. Zig-zag decking sections cut from roundwood are suitable for use as decking or glulam beams and joists. Testing shows the sections have moduli of elasticity of 1-1.8 million psi and are well-suited for short-span bridges and building applications.

1. WOOD I-BEAMS AND “ZIG-ZAG”
DECKING FROM ROUNDWOOD
INNOVATIVE AND EFFICIENT STRUCTURAL
SECTIONS FROM ROUNDWOOD
SUSTAINABLE DESIGN
Brad Miller P.E. HDR Engineering, Inc.
Tom Gorman P.E., Ph.D. University of Idaho
FPS 65th International Convention
Portland, Oregon June 19-21,2011

2. WOOD I-BEAMS FROM ROUNDWOOD
 Dap Flanges As Shown, Or Flat All Four Sides

3. WOOD I-BEAMS FROM ROUNDWOOD
 Dap Flanges As Shown, Or Flat All Four Sides
 Uses Over 90% Of Material (For Ideal Round)

4. WOOD I-BEAMS FROM ROUNDWOOD
 Dap Flanges As Shown, Or Flat All Four Sides
 Uses Over 90% Of Material (For Ideal Round)
 Increases Ix-x (Strength) By 4.5 To 5 Times

5. WOOD I-BEAMS FROM ROUNDWOOD
 Dap Flanges As Shown, Or Flat All Four Sides
 Uses Over 90% Of Material (For Ideal Round)
 Increases Ix-x (Strength) By 4.5 To 5 Times
 Sizes Possible From 6 to 48-Inches

6. WOOD I-BEAMS FROM ROUNDWOOD
 Dap Flanges As Shown, Or Flat All Four Sides
 Uses Over 90% Of Material (For Ideal Round)
 Increases Ix-x (Strength) By 4.5 To 5 Times
 Sizes Possible From 6 to 48-Inches
 Comparable To Glulams Of Similar Dimensions

7. WOOD I-BEAMS FROM ROUNDWOOD
 Dap Flanges As Shown, Or Flat All Four Sides
 Uses Over 90% Of Material (For Ideal Round)
 Increases Ix-x (Strength) By 4.5 To 5 Times
 Sizes Possible From 6 to 48-Inches
 Comparable To Glulams Of Similar Dimensions
 Suitable For Buildings And Short-span Bridges

8. WOOD I-BEAMS FROM ROUNDWOOD
 Dap Flanges As Shown, Or Flat All Four Sides
 Uses Over 90% Of Material (For Ideal Round)
 Increases Ix-x (Strength) By 4.5 To 5 Times
 Sizes Possible From 6 to 48-Inches
 Comparable To Glulams Of Similar Dimensions
 Suitable For Buildings And Short-span Bridges
 Excellent Use Of Bug-Killed Or Low Value Trees

9. WOOD I-BEAMS FROM ROUNDWOOD
 9-Inch Test Specimens From 6-Inch +/- Roundwood

10. WOOD I-BEAMS FROM ROUNDWOOD
Properties and Additional Information Available 6” To 48”

11. ZIG-ZAG SECTIONS FROM ROUNDWOOD
 Use Horizontally For Decking
 Glulam Or Nail-Lam

12. ZIG-ZAG SECTIONS FROM ROUNDWOOD
 Use Horizontally For Decking
 Glulam Or Nail-Lam
 Use Glulams Vertically
 Use For Buildings Or Bridges

13. ZIG-ZAG SECTIONS FROM ROUNDWOOD
 Use Horizontally For Decking
 Glulam Or Nail-Lam
 Use Glulams Vertically
 Use For Buildings Or Bridges
 6-Inch Makes 2.5-Inch +/-

14. ZIG-ZAG SECTIONS FROM ROUNDWOOD
 Use Horizontally For Decking
 Glulam Or Nail-Lam
 Use Glulams Vertically
 Use For Buildings Or Bridges
 6-Inch Makes 2.5-Inch +/-
 8-Inch Makes 3.375-Inch +/-

15. ZIG-ZAG SECTIONS FROM ROUNDWOOD
 Use Horizontally For Decking
 Glulam Or Nail-Lam
 Use Glulams Vertically
 Use For Buildings Or Bridges
 6-Inch Makes 2.5-Inch +/-
 8-Inch Makes 3.375-Inch +/-
 10-Inch Makes 4.25-Inch +/-

16. ZIG-ZAG SECTIONS FROM ROUNDWOOD
 Use Horizontally For Decking
 Glulam Or Nail-Lam
 Use Glulams Vertically
 Use For Buildings Or Bridges
 6-Inch Makes 2.5-Inch +/-
 8-Inch Makes 3.375-Inch +/-
 10-Inch Makes 4.25-Inch +/-
 12-inch Makes 5.125-Inch +/-

17. ZIG-ZAG SECTIONS FROM ROUNDWOOD
 Use Horizontally For Decking
 Glulam Or Nail-Lam
 Use Glulams Vertically
 Use For Buildings Or Bridges
 6-Inch Makes 2.5-Inch +/-
 8-Inch Makes 3.375-Inch +/-
 10-Inch Makes 4.25-Inch +/-
 12-inch Makes 5.125-Inch +/-
 Excellent Use Of Bug-Killed
Or Low Value Trees

18. ZIG-ZAG SECTIONS FROM ROUNDWOOD
 Vertical Orientation Good For Joists and Beams

19. ZIG-ZAG SECTIONS FROM ROUNDWOOD
 Zig-Zag Decking Sample Showing Cuts and Layout

20. SUITABILITY FOR BRIDGE AND BUILDINGS
 Wood I-Beam And Zig-Zag Sections Especially Suitable
For Trail And Short Span Bridge Configuration

21. SUITABILITY FOR BRIDGE AND BUILDINGS
 Wood I-Beam And Zig-Zag Sections Especially Suitable
For Trail And Short Span Bridge Configuration
 Spans Would Be About 2X That For Roundwood Stock

22. SUITABILITY FOR BRIDGE AND BUILDINGS
 Wood I-Beam And Zig-Zag Sections Especially Suitable
For Trail And Short Span Bridge Configuration
 Spans Would Be About 2X That For Roundwood Stock
 Wood I-Beam And Zig-Zag Sections Also Good For
Buildings – Decking, Headers and Beams

23. Prototype evaluation

25. Assembly

26. Metriguard E-computer Director HM200
MOE dyn of I-beam (psi)
2.20E+06
MOEdyn = (ρ/g) x V2
1.80E+06 y = 1.0315x + 370781
R² = 0.8252
1.40E+06
1.00E+06
0.80 1.00 1.20 1.40 1.60 1.80 2.00
Million psi
MOE of web member

27. Static testing

28. Failure modes

29. Failure modes

30. Estimated design values
MOE (determined using stress wave velocity)
1,000,000 to 1,800,000 psi
Ave MOR = 7,317 psi 95th percentile = 5,167 psi
Fb ≈ 2,460 psi
Ave fv = 871 psi 95th percentile = 616 psi
Fv ≈ 290 psi

31. SUITABILITY FOR BRIDGE AND BUILDINGS
 Wood I-Beam And Zig-Zag Sections Especially Suitable
For Trail And Short Span Bridge Configuration
 Spans Would Be About 2X That For Roundwood Stock
 Wood I-Beam And Zig-Zag Sections Also Good For
Buildings – Decking, Headers and Beams