Thirteen Ed Online - Building Bridges

		Design Brief Building Bridges Design and construct a bridge that will span a 36" wide by 8" deep gorge. The bridge should be built to scale, so you must figure out what the measurements would be if the gorge were 1000 yards. (Hint: Set your scale to 1 yard = 1000 yards.) Resources: Time: 15 class periods. People: Teams of 2 - 3. Capital: None. Energy: Human for construction, electrical for fabrication. Information: Knowledge of structures and bridge designs, forces, moments. Tools and Equipment: Hand tools, power miter saw, computer. Materials: Glue, rulers, pencils, graph paper, assorted wood, assorted screws and hardware, nylon twine, and fishing line. Other specific criteria: Keep a record of every step of your research and construction. Complete a "full size" side view drawing of your design. Craftsmanship counts! Work in a safe and cautious manner. Designs should be free of dangerous protrusions and the like. Always wear safety glasses. Make sure that your scale design maintains proportion. See your teacher for help with this. Testing Method: Use a block of wood placed at the center of the roadway to hang weights over. Cut nylon twine into 24" lengths, looping one end and attach a 2" by 3/8" piece of dowel rod to the other end to secure the loop once the weight has been hung on the twine. This will allow you to concentrate the weight at the point where you want to load the bridge. Hang the weights in 5 lb. increments so you can record the deflection (bending of the road surface) at even intervals. Keep going until the bridge breaks, or you reach 300 lbs.