Rebuilding the Bay Bridge SCIENCE ENGINEERING PROJECT Fall 1999 The San Francisco-Oakland Bay Bridge is in danger of being struck by an earthquake. Since the predictions are 70% that an earthquake bigger than a 7 on the Richter scale will strike the Bay Area in the next 30 years, the Bay Bridge needs to be strong enough to withstand failure in the next earthquake. Your job will be to build a prototype for one part of the bridge which will be anchored on two sides-the cantilever section-which is the part of the bridge between Oakland and Yerba Buena Island. You will build this model out of pasta and your prototype will go under several tests to see if it can meet the mass requirements needed to hold traffic and to see if it can withstand an earthquake. WHAT TO DO: I. Your group will build a bridge out of pasta. You can ONLY use vermicelli (angel hair), spaghetti, or linguini. You will be able to bundle the pasta together to create stronger beams. 2. The joints you use to connect your pasta can only be the following items; stale marshmallows, straws no longer than 3 centimeters long, rubber bands, or hot glue only at the joints. You may use any combination of the items listed. 3. Your prototype bridge must span a distance of 50 cm. We will provide the base on each side that your bridge will rest upon. You can extend your bridge onto these buttresses to a maximum of 10 cm on both sides. The bridge must have a width of 15 cm. You will use Velcro secures on the bottom of your anchors that should not be longer than 15 cm long and about 2.2 cm wide (1 inch). The anchors will have Velcro on them so that your bridge will be secured. 4. You must be able to put a roadway on your bridge that will be made out of standard poster board. Your bridge must have railings so that cars can't drive off the side. It cannot be a straight plank of pasta. 5. Your entire bridge, joints included must not exceed a mass of 500 grams (1/2 a kilogram). Those bridges with a mass larger than 5OOg will be disqualified. 6. You will work in a group of 2-4 students. You may work with students from other classes if both teachers approve. Choose your groups wisely as you will be meeting outside class time. If you work with students outside your science period the testing of your bridge is done in one period ONLY. You will have to decide which period, and someone will not be able to observe the tests. TESTING YOUR BRIDGE - Bridges are due WEDNESDAY DECEMBER 8, 1999 Your bridge will be subjected to a number of tests to determine its strength and its ability to withstand an earthquake. The bridges must be approved for meeting all qualifications before tests are run on it. The official approval will be the day of the tests, December 9. The following tests must be met one at a time to progress to the next level of testing. Test I- Four 500 g masses will be placed on your roadway supported by your bridge. If your bridge is successful in holding these masses you will move to test 2. Test 2- Eight 500 g masses will be placed on the roadway supported by your bridge. If your bridge successfully supports these masses you will move to test 3. Test 3- Your bridge will undergo an earthquake simulation. During this simulation there will be a swift sheer movement placed on your bridge. JOURNAL You must keep written records of your designs and trials. This journal must be hand written and done as you meet with your group. Each individual student is expected to turn in a journal that includes a drawing of your final design. Individual teachers will give you additional information. WRITTEN COMPONENT Each student will do research on the San Francisco-Oakland Bay Bridge. Address the following questions: I. What earthquake faults do scientists think will affect the Bay Bridge? What earthquake fault caused the 1989 earthquake? How did the Bay Bridge fail in that earthquake? 2. What has been done and is currently being done to retrofit the Bay Bridge? 3. Discuss at least two current designs being considered to replace the Bay Bridge. What are the positive and negative parts of each of the designs?