Two Bridges Built Using Black Locust Wood

2nd International Conference on Timber Bridges

Ryan Woodward

Ted Zoli

Las Vegas, 2013

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 2

Squibb Bridge

Brooklyn, NY

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 3

FURMAN STREET

121’-0”

SQUIBB PARK

(BEYOND)

17’-0”

CL

.

5%

121’-0”

HOTEL/RESIDENTIAL

(BEYOND)

DRIVEWAY 12’-6”

CL

.

Underslung Suspension Bridge: • Highly efficient form

• Material palette from BBP

• Small dia. Black Locust

• Steel cables & connections

VIEW A-A

PLAN

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 4

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 5

Black Locust Timber:

• Sustainable • Small diameters – harvested young • Fast growth • Locally sourced • Rot resistant – no coating required

• Strong • Low shrinkage

(11.4% vol.)

Galvanized steel cables & hardware

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 7

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 8

Ratios of dry to green clear wood properties

Modulus of Rupture Modulus of Elasticity Compression Parallel to Grain

1.40 1.11 1.50

(ASTM D2555)

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 9

Locust Borer

(Megacyllene robiniae)

Lunch

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 10 Timber Piles – standard and proprietary connections

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 11

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 12

Structural Systems - Triakonta:

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 13

Turning a Black Locust Log, Cornell University, 2010

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 14

Structural Systems – Prestressed Segmented Arch:

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 15

Annular band connections on communication towers up to 40 m tall.

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 16

• Capped end connections

• Modular kit-of-parts

• Simple fabrication & erection

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 17 Four Bar Linkage

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 18

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 19

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 20

Squibb Bridge

Brooklyn, NY

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 21

TA Footbridge

Vassar College, Poughkeepsie, NY

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 22

Pressure treated wood deck, on unpainted steel beams

Advanced corrosion, significant section loss

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 23

Elevation

Axial force in lattice members (kips)

AASHTO STR-I combo

Axial force in chords & arch rib (kips)

X

Y

Z

-1.0

-1.3

-2.0

-2.5

-3.2

-5.6

X

Y

Z

60.0

-47.9

Elevation

Axial force in lattice members (kips)

AASHTO STR-I combo

Axial force in chords & arch rib (kips)

X

Y

Z

-1.0

-1.3

-2.0

-2.5

-3.2

-5.6

X

Y

Z

60.0

-47.9

Axial force in chords & arch rib (kips) Axial force in lattice members (kips)

AASHTO Strength-I Combination

Elevation

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 24

-4-2024

V0 VAB VBC VCD VD

Shea

r (k

ips)

Peg Shear Diagrams Top Chord

Section - Top Chord

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

B1

B3

B5

B7

B9

B1

1B

13

B1

5B

17

B1

9B

21

B2

3B

25

B2

7

No

. of P

egs

Bo

tto

m C

ho

rdM

ax. S

hea

r (k

ips)

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

T1 T4 T7 T10

T13

T16

T19

T22

T25

T28

No

. of P

egs

Top

Ch

ord

Max

. Sh

ear

(kip

s)

L BRIDGE (SYMM.)

C

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

A1

A3

A5

A7

A9

A1

1A

13

A1

5A

17

A1

9A

21

A2

3A

25

A2

7

No

. of P

egs

Arc

h R

ibM

ax. S

hea

r (k

ips)

Panel Point

Max Shear Force per shear plane (kips) No. of Pegs Figure 6 TA Bridge: maximum shear force per peg

shear plane and no. of pegs at each panel point.

-4-2024

V0 VAB VBC VCD VD

Shea

r (k

ips)

Peg Shear Diagrams Top Chord

Section - Top Chord

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

B1

B3

B5

B7

B9

B1

1B

13

B1

5B

17

B1

9B

21

B2

3B

25

B2

7

No

. of P

egs

Bo

tto

m C

ho

rdM

ax. S

hea

r (k

ips)

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

T1 T4 T7 T10

T13

T16

T19

T22

T25

T28

No

. of P

egs

Top

Ch

ord

Max

. Sh

ear

(kip

s)

L BRIDGE (SYMM.)

C

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

A1

A3

A5

A7

A9

A1

1A

13

A1

5A

17

A1

9A

21

A2

3A

25

A2

7

No

. of P

egs

Arc

h R

ibM

ax. S

hea

r (k

ips)

Panel Point

Max Shear Force per shear plane (kips) No. of Pegs Figure 6 TA Bridge: maximum shear force per peg

shear plane and no. of pegs at each panel point.

Mode V (peg shear failure)

(Miller, Schmidt, & Bulleit)

TA Footbridge Peg Shear Diagrams

Sh

ear

(k

ips)

4

2

0

2

4

Section – Top Chord

Yield modes of failure for doweled connections

(Timber Framers Guild)

1 2 3

1 2 3

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 25

Elevation

Axial force in lattice members (kips)

AASHTO STR-I combo

Axial force in chords & arch rib (kips)

X

Y

Z

-1.0

-1.3

-2.0

-2.5

-3.2

-5.6

X

Y

Z

60.0

-47.9

-4-2024

V0 VAB VBC VCD VD

Shea

r (k

ips)

Peg Shear Diagrams Top Chord

Section - Top Chord

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

B1

B3

B5

B7

B9

B1

1B

13

B1

5B

17

B1

9B

21

B2

3B

25

B2

7

No

. of P

egs

Bo

tto

m C

ho

rdM

ax. S

hea

r (k

ips)

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

T1 T4 T7 T10

T13

T16

T19

T22

T25

T28

No

. of P

egs

Top

Ch

ord

Max

. Sh

ear

(kip

s)

L BRIDGE (SYMM.)

C

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

A1

A3

A5

A7

A9

A1

1A

13

A1

5A

17

A1

9A

21

A2

3A

25

A2

7

No

. of P

egs

Arc

h R

ibM

ax. S

hea

r (k

ips)

Panel Point

Max Shear Force per shear plane (kips) No. of Pegs Figure 6 TA Bridge: maximum shear force per peg

shear plane and no. of pegs at each panel point.

-4-2024

V0 VAB VBC VCD VD

Shea

r (k

ips)

Peg Shear Diagrams Top Chord

Section - Top Chord

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

B1

B3

B5

B7

B9

B1

1B

13

B1

5B

17

B1

9B

21

B2

3B

25

B2

7

No

. of P

egs

Bo

tto

m C

ho

rdM

ax. S

hea

r (k

ips)

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

T1 T4 T7 T10

T13

T16

T19

T22

T25

T28

No

. of P

egs

Top

Ch

ord

Max

. Sh

ear

(kip

s)

L BRIDGE (SYMM.)

C

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

A1

A3

A5

A7

A9

A1

1A

13

A1

5A

17

A1

9A

21

A2

3A

25

A2

7

No

. of P

egs

Arc

h R

ibM

ax. S

hea

r (k

ips)

Panel Point

Max Shear Force per shear plane (kips) No. of Pegs Figure 6 TA Bridge: maximum shear force per peg

shear plane and no. of pegs at each panel point.

-4-2024

V0 VAB VBC VCD VD

Shea

r (k

ips)

Peg Shear Diagrams Top Chord

Section - Top Chord

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

B1

B3

B5

B7

B9

B1

1B

13

B1

5B

17

B1

9B

21

B2

3B

25

B2

7

No

. of P

egs

Bo

tto

m C

ho

rdM

ax. S

hea

r (k

ips)

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

T1 T4 T7 T10

T13

T16

T19

T22

T25

T28

No

. of P

egs

Top

Ch

ord

Max

. Sh

ear

(kip

s)

L BRIDGE (SYMM.)

C

0

1

2

3

4

0.00.51.01.52.02.53.03.54.0

A1

A3

A5

A7

A9

A1

1A

13

A1

5A

17

A1

9A

21

A2

3A

25

A2

7

No

. of P

egs

Arc

h R

ibM

ax. S

hea

r (k

ips)

Panel Point

Max Shear Force per shear plane (kips) No. of Pegs Figure 6 TA Bridge: maximum shear force per peg

shear plane and no. of pegs at each panel point. Computed shear force per peg shear plane

Axial force in chords & arch rib (kips) Axial force in lattice members (kips)

AASHTO Strength-I Combination

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 26

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 27

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 28

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 29

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 30

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 31

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 32

Testing Full-Size Members for Squibb Bridge

(Univ. of Maine)

150 mm diameter x 1.83 m logs

(6” dia. x 72”)

50 mm x 200 mm x 2.49 m beams

(4” x 10½” x 98”)

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 33

Compression

Parallel to Grain n

Ultimate

Compressive Strength

Modulus of

Elasticity

Moisture

Content

Specific

Gravity

Me

an (

ksi)

CO

V (

%)

PT

L

Me

an (

ksi)

CO

V (

%)

MC

(%

)

CO

V (

%)

Me

an

CO

V (

%)

FPL

Wh

ite

Oak

20 3,560 18 2,321 * 1,250 22 Grn - 0.60 10

FPL

Bla

ck

Locu

st

20 6,800 18 4,434 * 1,850 22 Grn - 0.66 10

Sq

uib

b

Bri

dg

e

45 5,219 12.2 4,051 * 1,770 16.2 24.8 17.0 0.61 4.1

TA

Foo

t

bri

dg

e

41 7,156 20.8 4,424 * 1,327 49.5 - - - -

Compression Strength: Two rounds of testing

* PTL = lower 5% at 75% confidence

(ASTM D2915)

TWO BRIDGES BUILT USING BLACK LOCUST WOOD 34

0

5

10

15

20

25

1,0

00

2,0

00

3,0

00

4,0

00

5,0

00

6,0

00

7,0

00

8,0

00

9,0

00

10

,00

01

1,0

00

Co

un

ts

UCS (psi)

0

5

10

15

20

25

1,0

00

2,0

00

3,0

00

4,0

00

5,0

00

6,0

00

7,0

00

8,0

00

9,0

00

10

,00

01

1,0

00

Co

un

ts &

Wei

bu

ll P

rob

abili

ty

UCS (psi)

0

5

10

15

20

25

1,0

00

2,0

00

3,0

00

4,0

00

5,0

00

6,0

00

7,0

00

8,0

00

9,0

00

10

,00

01

1,0

00

UCS (psi)

Block ABlock BCombined WeibullBlock A WeibullBlock B Weibull

Compression Strength: Two rounds of testing

Squibb Bridge

TA Footbridge

Use caution drawing comparisons.

It may not be reasonable to combine the data sets.

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