National Timber Bridge Design Competition –2019

College or University Name: SUNY College of Environmental Science and Forestry

Student Chapter (ASCE or FPS): FPS

Address: 1 Forestry Dr. Syracuse, NY 13210

Website Address: www.esf.edu

Faculty Advisor: Dr. Paul Crovella

Email: plcrovella@esf.edu

Phone: (315) 470-6839

Student Member in Charge of Project: Elijah Meier

Email: efmeier@syr.edu

Phone: (518) 821-0167

Team Member Roles Class

Elijah Meier Project Manager 2019

Brad Howes Drawings & Estimating 2019

Alex McGill Construction and Testing 2019

McKenna Pason Designing & Engineering 2020

Erika Gripp Competition Submission Coordinator 2020

Hours Spent on This ProjectStudents:185Faculty:10Cost of MaterialsDonated: $0Purchased: $1,123.52

Abstract (Maximum 500 Word Narrative): Explain the bridge design concept and what was done to optimize stiffness while attemp ting to minimize weight of the structure.

This bridge will be located in a client’s backyard in Jamesville NY to account for a difference in land elevation and make it easier to walk, as well as maintain the property. The team decided to keep the bridge as a simple to construct.

The construction of the bridge began with drying all wood members in the kiln then, planning and jointing the boards that would compose the glulam beam after it has reached appropriate moisture content. The two 18 foot

structural beams were then glued together, consisting of four 2x8s face to face, as well as one 2x6s on the top, and one 2x6 cut to 5 ⅝” on the bottom glued and screwed down with decking screws on both the top and bottom of the beam.

Due to the member length limit, each component of the beam was cut and glued back together using a 45 degree angle scarf joint method. Titebond 3 waterproof wood glue was used for all gluing applications.

Perpendicular to the glulam beam are thirteen joists, 5 feet long 2x12s, mounted to the face of the beams using an 18 gauge triple zinc face mount joist hanger. The joist hanger is mounted using 9-gauge hot-dipped galvanized steel common nails. These members of the bridge support the decking, which is comprised of 30 2x6s 6 feet long on face

screwed in with Primeguard Plus #10 x3 ½ in polymer deck screws.

By gluing and connecting the structural beams of the deck with screws, nails and joist hangers as well as drying all of our lumber, we were able to achieve a maximum stiffness of the bridge. The glue also enabled us to minimize the

weight of the structure significantly while still maintaining the structural integrity of the wood.

1. Loading Increment 2. Bridge 3. Beam

LEFT

4. Beam

RIGHT

5. Average

(L & R)

6. Gross Deck 7. Net Deck

5 kN 0.66 2.72 2.64 2.68 3.56 0.88

10 kN 2.54 5.36 5.31 5.34 6.53 1.19

15 kN 3.39 7.67 7.72 7.70 9.32 1.62

20 kN – 0 min. 3.56 10.31 10.13 10.22 12.06 1.84

20 kN – 15 min. 3.86 10.67 10.62 10.65 12.52 1.87

20 kN – 30 min. 3.94 10.77 10.74 10.76 12.65 1.89

20 kN –45 min. 3.96 10.87 10.82 10.85 12.75 1.90

20 kN – 60 min. 4.06 10.92 10.89 10.91 12.80 1.89

1. Loading Increments2. Bridge – As measured at midspan of the longitudinal beam receiving greatest loading.3. Beam L – As measured under the longitudinal beam to left of selected deck monitoring point.4. Beam R – As measured under the longitudinal beam to right of selected deck monitoring point.5. Average (L & R) – Average of 3 and 4, above.6. Gross Deck – As measured under the loading point expected to experience maximum deflection.7. Net Deck – Column 6 minus Column 5.Deck Span:Transverse distance between main longitudinal bridge support members measured from inside edge to inside edge = ____1828.80____mm ÷ 100 = ____18.29___mm = maximum allowable net deck deflection.

2. Deflection Table (Deflection – millimeters rounded to 2 decimal places)

Material Item Description Weight (kg)(28) 2x10x8 #2 Prime Treated Lumber 1.45 per ft

(15) 2x8x8 #2 Prime Treated Lumber 1.22 per ft

(8) 2x12x12 #2 Prime Treated Lumber 1.81 per ft

(25) 2x6x12 #2 Prime Treated Lumber 0.75 per ft

(5 lbs) Primeguard Plus #10 x3 ½ in Polymer Deck Screws 2.27

(5 lbs) 3 in 9-Gauge Hot-Dipped Galvanized Steel Common Nails 2.04

(26) 2x10 18-Gauge Triple Zinc Face Mount Joist Hanger 4.68

(3) 8 ft Anti-Slip Tape 0.23

(16 fluid oz) Brown Interior/Exterior Wood Adhesive 3.79

(128 fluid oz) Brown Interior/Exterior Wood Adhesive 1.90

TOTAL WEIGHT (Kg) 616.61

Weight Non-Wood (Kg) 13.32

Percent Non-Wood (max. 25%) 2.16%

3. Materials List

4. Summary – Describe Bridge and Its Behavior Under Load (max. 500 words)

Through our design calculations, we predicted the deflection of the bridge to be near the competition requirements of 18.29 mm. Our bridge actually had an our greatest deflection of 4.27 mm which is acceptable under our total span. Our bridge is too large to fit under our testing machine, so we tested using increments of 70 lb sandbags. The bridge seemed very stiff during the loading of

each increment of sand bags, with no visible by the eye deflection. Our team heard a few quiet creaking noises but we suspected it was the base of our loading set up to hold the sandbags in place,

which was composed of some large wood members that totalled 280 lbs. accounted for when starting the first increment of the loading test. The decking, joists and beams all had minimal

deflection even with the 20 KN load on for an hour. Our team is pleased and impressed with how our bridge performed during the load testing.

Side Drawing (insert below)

End Drawing (insert below)

End Drawing (insert below)

Trimetric Drawing (insert below)

Drawing Clearly Showing Location of Loading and Deflection Gage Points in Relation to Longitudinal Members (insert below)

NOTE: Repeat slide if loading set-up was moved to measure deck deflection.

Drawing Clearly Showing Location of Loading and Deflection Gage Points in Relation to Transverse Members (insert below)

NOTE: Repeat slide if loading set-up was moved to measure deck deflection.

PHOTO Showing SIDE View of Loading Setup #1 for Measuring Bridge Deflection (insert below)

PHOTO Showing END View of Loading Setup #1 for Measuring Bridge Deflection (insert below)

PHOTO Showing SIDE View of Loading Setup #2 for Measuring Bridge Deflection (insert below)

NOTE: Repeat slide if loading setup was moved to measure deck deflection.

PHOTO Showing END View of Loading Setup #2 for Measuring Bridge Deflection (insert below)

NOTE: Repeat slide if loading set-up was moved to measure deck deflection.

End Photo of Finished Bridge

Side Photo of Finished Bridge

Trimetric Photo of Finished Bridge

Team Photo (with bridge in the foreground, where possible)

Briefly describe each bridge component, as applicable.

Joists Thirteen 2x12 by 5’ long

Decking 2x6 by 6’ long boards running parallel to the span

Floor Beams Two 18’ 12.25”x5.5” Glulam Beams composed of 4 wide 2x10s on edge and 1 2x6 on face on top and bottom

Suspension No suspension

Unique Components Creating a Glulam Beam and using 2x12 joist hangers to hold secondary members

6. Bridge Component Details

7. Preservative Treatment: Describe the preservative treatment applied to all wood members. Include type and concentrations. Also, include a short statement of why this

treatment was selected. Did the treatment requirement present any special problems? If yes, provide details. If treatment was not selected, explain why.

All wood members were treated with chromium copper azole type C by Lowes to protect all pieces from the elements. This treatment was selected to account for the direct

ground to wood contact, as well as the permanent outdoor use of the bridge. The treatment was applied before purchase and did not present any special problems. The

team also selected Primeguard Plus polymer deck screws, as well as hot-dipped galvanized steel common nails to fasten certain bridge members together. By choosing

these treated fasteners, the team is ensuring the bridge can withstand weathering without rusting or other moisture related issues resulting from the connections. The treatment left the members with a higher moisture content than normal, where we

needed a low moisture content in some members because of our use of glue needing a dry clean wood.

8. Special Considerations –Indicate the End Use of Your Bridge

Our client would like this bridge on his property in Jamesville NY to span across an 18 foot gap caused by a difference in land

elevation on his property, as well as to add to an aesthetic backyard landscape. More specifically, he wants the bridge to

make it easier to get from one side to the other for not only himself, but also his grandchildren. Thus, Non-Slip grip tape will be added after installation of bridge. The bridge will mainly be used for light foot traffic, but it is also designed to hold various lawn care equipment, such as a a ride-on lawn mower and a

snow blower.

Final Bridge Placement Jamesville, New York

9. Summarize the Team’s Experience from Participation in this Competition. Was it beneficial? What steps would you

recommend to improve the experience?

Overall, we found this competition to be a great experience to learn the real applications of seeing a project from start to finish, as well as hands on

construction involvement. We found the freedom of design to be very beneficial because it allowed our team to create a bridge that will best benefit the owner, as well as meet the competition requirements and our inexperience in woodworking.

The most difficult requirements for our team to meet was the maximum member length of 2.1 meters. We did not want any of our joints to line up to avoid stiffness issues, but it was very difficult to achieve that with the maximum member length

causing there to be many joints on our bridge.

Also since these bridges are almost always used in a real life application after the competition, the member length can be very difficult and restraining for the design

as a whole.

Photo of Bridge Weighing

One photo of each deflection gauge at full loading, with identification sign indicating DECK, BEAM LEFT, BEAM RIGHT, BRIDGE.

20 kN Bridge Deflection gauges (Test #1) - 60 mins

Bridge Beam Right Deck Beam Left

One photo of each deflection gauge at full loading, with identification sign indicating DECK, BEAM LEFT, BEAM RIGHT, BRIDGE.

20 kN Deck Deflection gauges (Test #2) - 60 mins

Bridge Beam Right Deck Beam Left

Add as many photos as you wish showing the bridge construction process. Especially consider photos of internal structural components that may not be visible to judges from observing the

finished bridge.

Add as many photos as you wish showing the bridge construction process. Especially consider photos of internal structural components that may not be visible to judges from observing the

finished bridge.