Tufts Buildable Bridge

Segmental Box Beam Bridge Construction Manual

Professor Brian Brenner, PE Tufts University

Medford, MA – 02155

Kevin Walsh Ishmael Alleyne

Mark Pinkos Jason Karp

History of Segmental Bridges First pre-cast pre-stressed segmental concrete bridge The first pre-cast pre-stressed segmental concrete bridge

constructed was the Choisy-le-Roi Bridge in France from 1962 – 1965.

The Choisy-le-Roi Bridge, which was designed by Jean Muller, is a road

bridge that crosses the Seine River, has a total length of 131m,

individual spans of 38m – 55m – 38m, and a deck width of 28.4m.

First cast-in-place segmental concrete bridge The first cast-in-place segmental concrete bridge constructed was the

Balduinstein Bridge in 1950 in Germany using the balanced cantilever

method. The Balduinstein Bridge, which was designed by Ulrich

Finsterwalder, is a road bridge that crosses the Lahn River and has a

main span of 62 m.

First U.S. pre-cast segmental concrete bridge In 1973, the first U.S. pre-cast segmental concrete bridge was built

and opened to traffic in Corpus Christi, Texas. In 1974, the first U.S.

cast-in-place segmental bridge was built and opened to traffic near

San Diego, California.

Where & When to use Segmental Bridges

• Environmentally sensitive areas where disruption to the ground surface must be minimized (e.g., wetlands, slopes subject to erosion or areas with hazardous materials).

• Reconstruction of large-scale urban expressways where disruption to existing operations must be minimized or eliminated.

• Repetitive bridge projects that lend themselves to standardization of structural components and construction activities, such as long transit viaducts or elevated expressways.

• Long-span bridges over navigable waterways, long crossings over water or crossings over waterways subject to scouring or unique hydraulic features.

• Bridges over areas with poor construction accessibility, such as steep terrain or canyons.

• Large-scale projects where a bridge’s construction schedule needs to be compressed to fit overall project schedule limitations.

Assembly Procedure

Balanced Cantilever Method: Step 1: Place Pier A-B on table top.

Step 2: Locate: - 6 wooden dowels - Segments A1, A2, A3

and B1, B2, B3

Step 3: Place segment A1 against A-Side of pier. The pier’s wooden pegs will insert into the holes in segment A1.

Step 4: Put one dowel through the top rubber band on pier. Stretch rubber band outward from pier.

Step 5: Let rubber band pull dowel into slot on outer edge of segment A1.

Step 6: Repeat steps 3, 4, and 5 for each segment in the following order: B1, A2, B2, A3, B3. Note: Each segment added should use the highest unused rubber band on the pier. This will keep the weight of the segments balanced on each side of the pier.

Progress Check: Your bridge should now look like this.

Notice how the bridge sags under the weight of

the segments.

Step 7: We will now add the final support. Locate:

(1) Steel threaded rod (1) Nut and Washer (1) Wing Nut

This will give the bridge more bending support so that it does not sag.

Step 8:

Remove Wing nut from threaded rod and insert the rod through the bridge deck entering from the B-Side of the pier. Note: Make sure the nut and washer are in the counter-sunk hole.

This step should be completed by an adult.

Step 9: Tighten wing nut on A-Side of bridge. Hold nut stable on the opposite side while tightening.

Progress Check: Your bridge should now look like this. Notice how the bridge no longer sags under the weight of the segments.

Step 10: Repeat steps 1 through 9 with Pier C-D and segments C1, C2, C3, D1, D2, and D3.

D C B A

Step 11: We will now connect the two halves using the Keystone. Line up the bridge halves and place the Keystone in the gap. The notches in the Keystone fit around the pegs in segments B3 and C3.

Step 12: Now we install the final support, a very long rubber band. Stretch the colored rubber band from the C-Side of the first pier to the B-Side of the second pier. It hooks onto the white hook on the pier face.

Congratulations: Your bridge is now complete and should look like this:

Cast-in-Place Method: Step 1: Locate the scaffolding.

Step 2: Place the scaffolding beneath where the next segment will go.

Step 3: Place the incoming segment on top of the scaffolding. And secure the segment using the wooden pegs.

Step 4: Fully install the segment using the dowel and rubber band as done in balanced cantilever method steps 3 through 5. Note: Repeat this sequence for all segments in the bridge.

Gantry Crane Method: This construction technique can only be used for the segments between the two piers on this model. Step 1: Place Gantry crane so that the four legs sit on the two piers.

Step 2: Place any interior segment on table top beneath the gantry crane. Attach segment to the hooks under the segment’s deck. (There are small holes)

Step 3: Lift segment using crane wires to appropriate height. Then follow normal procedure to secure the segment against pier or previous segment.

Step 4: Repeat this sequence for all segments in the bridge until bridge is completed.