Wood I-Joists Made of Corrugated Veneer Web Panel

Levente Dénes

PTF BPI 2010 October 7-8, 2010 Kuchl

Inst. of Product Development and ManufacturingUniversity of West Hungary

Objectives:

1. To survey the volume, size and availability of veneer residue in the Appalachian region;

2. To develop viable technologies for manufacturing highly engineered structural manufacturing highly engineered structural products;

3. To determine the mechanical properties of the new products;

4. To develop a long-term research program targeted to converting waste materials into value added products.

Specific Objectives:

1. To investigate the effect of construction parameters on bending performance of the joists

2. To determine the bending strength and 2. To determine the bending strength and stiffness of the I-joists made of hardwood veneer clippings;

3. To analyse the load bearing capacities of different web-flange joint types;

4. To determine the tensile strength of various web-web joints.

Veneer clippings:

Veneer sheets

Knife

Hold down

Anvil1~1.5”

Heat generation Value addedd products

1~1.5”

How much material is available?N

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2

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4

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6

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Clippings per annum x 104 (tons)Number of responding manufacturers

Other Species 10.8 %

Cherry 10.4 %

Hard maple 4.3 %

Read oak 4.9 %White ash 0.2 %

Yellow-poplar 69.4 %

~ ~ 60 000 tons of clipping residue annually in the central Appalachian region;

~ 90 % of it used as fuel for steam generation, the rest is mulched.

~ 13 million board-feet of structural composite may be produced from veneer waste.

States Surveyed

KY MD NY NC PA SC TN VA WV

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Veneer sheet production in the European Union (27)

Products developed from veneer clippings

Bearing capacity of I-beams

Limited by three different capacities:

� Bearing capacity of the flange immediately adjacent to the bearing.

� Bearing capacity of the web immediately adjacent � Bearing capacity of the web immediately adjacent to the flange above the bearing.

� Buckling of the web above the bearing.

Lateral supports used for I-beams

Corrugated web panel productionveneer clippings

+

+ hot press

<=corrugated panels

Press schedules for mat consolidation

Thickn., mm Density, kg/m3 IB, MPa

Average Average Std. Average Std.

Ash 8,2 729,1 66,4 1,390,40

Ash_wide_16 8,0 754,4 28,7 1,82 0,57Cherry narrow

7,9 736,1 65,9 1,56 0,48

Internal bond strength

narrow7,9 736,1 65,9 1,56 0,48

Cherry wide 7,6 679,4 23,8 1,64 0,48Box Plot for Internal Bond Stress Values

A A_16 Ch_N Ch_W

Panel Types

0,00

0,25

0,50

0,75

1,00

1,25

1,50

1,75

2,00

2,25

2,50

2,75

3,00

IB, M

Pa

IBOSB = 0.207 -0.483 MPa

Shear trough thickness

Parallel to grain Perpendicular to grainPanel ID Mpa Panel ID MpaCh_N_3 4,99 Ch_N_1 9,97

Ch_N_8 4,01 Ch_N_13 10,44

Ch_N_9 4,93 Ch_N_14 11,00

Ch_N_10 5,14 Ch_N_P1 11,16Ch_N_10 5,14 Ch_N_P1 11,16

Ch_N_11 4,48 Ch_N_P1 9,39

Ch_N_12 4,92

Joint type Fmax, kNTensile

strength,MPa

Mean CV, % Mean CV, %

Dovetail joint 14.9 32 9.2 20

Finger joint 39.9 26 25.3 25

Without joint 67.4 34 66.6 17

Web-to-web Joints’ Tensile Strength

Spec. Length,

m

Depth,

mm

Flange

width,

mm

Flange

thickness,

mm

Web

thickness

mm

Flange

material

Joint

type

1 3.66 231.8 42.9 33.3 5.1 PSL FJ

2 3.66 273.1 44.5 42.9 7.9 LVL FJ

I-joists geometrical properties

2 3.66 273.1 44.5 42.9 7.9 LVL FJ

3 3.66 301.6 55.6 39.7 6.4 PSL TG

4 3.66 287.3 50.8 34.9 7.9 LVL FJ

5 3.66 292.1 50.8 34.9 11.4 PSL FJ

6 3.66 306.4 57.2 44.5 4.4 LVL TG

7 2.44 236.5 57.2 44.5 12.7 LVL TG

8 2.44 266.7 57.2 38.1 9.1 PSL TG

9 2.44 417.5 85.7 34.9 10.2 LSL TG

I-joists four point bending test and the web-to-web joints tension tests

Spec. I, cm4 FMax, kN M, Nm MOR, MPa MOE, MPa

1 2862 6.6 3856 15.19 12548

2 5856 8.3 4823 11.44 8687

3 8085 17.7 10369 19.14 13169

I-joists mechanical properties

3 8085 17.7 10369 19.14 13169

4 6382 6.6 3843 8.60 12824

5 6920 8.3 4823 10.07 11997

6 9356 8.9 5190 8.54 12962

7 5075 25.5 10134 23.46 -

8 5801 22.1 8776 19.45 -

9 25387 44.5 17715 14.40 -

Tipical failure modes

� Efficient corrugated structural panel with a moderate wave geometry can be successfully produced from hardwood veneer side clippings using conventional mat forming and pressing methods

Conclusions

� Flexural properties of I-joists using corrugated web panels from hardwood veneers were comparable with conventional joist’s similar properties

� I-joists with finger joint web-flange connection failed in shear of glue line at the top or bottom joint while tongue and groove jointed beams failed in horizontal web shear

� Web-web finger joint connection decreased by half the tensile strength of the web panels, while dovetail joints reduced with almost 90 percent

� Further work needs to be done to optimize the web-flange

Conclusions

finger joint strength and to evaluate the local and global buckling behavior of the I-joists with corrugated veneer web panels

AcknowledgementsThe authors acknowledge the financial support of

USDA Wood Utilization Research Grant,

West Virginia University Wood Utilization Research Center

Hybrid Structural Wood Composites Engineered from Hybrid Structural Wood Composites Engineered from Underutilized Hardwood Species Combined with Reformulated Waste Materials and

Hungarian Scientific Research Fund.

Thank you for your Thank you for your honourable attention !