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Bridge Building

Each team will build a strong, stable, and free-standing bridge from 25 paper drinking straws and 1 meter of tape. The team that build the tallest bridge and holds an object for 10 seconds with the fewest straws will be the winner. This event has a written test component.

Number Students Allowed
2 per team
Impact Safety Glasses (ANSI Z87.1+)

Questions: (1) Are support structures used in this event?  On the one hand, the very first sentence in the event rules states that the team will build a "free-standing" bridge (seeming to imply no support structures), and the Bridge Testing Phase section makes no mention of the support structures and rather says that the bridge should be placed on a "tabletop or floor".  On the other hand, the list of "Materials Provided at Event" includes "2-5 cm x 9.5 cm x 30.5 cm support structures" so perhaps all that "free-standing" means is that the bridge cannot be taped to the support structures?   (2) What portion of the bridge design is allowed to be in contact with the ground surface (whether tabletop or support structure): is it just the two ends or can part of the span (e.g., structures below the deck) touch it?  (3) Do the ends of the span need to touch the tabletop (like Leonardo da Vinci’s self-supporting bridge) or can the entire span be elevated above the tabletop (as shown in the photo in the "Straw Bridges - The Stem Laboratory" link that's included in "Possible Resources")?   (4) Does the bridge need to measure 6 cm wide at its narrowest point, widest point, or center point? Related, is it the deck that has to be 6 cm wide or can any part of the bridge be 6 cm wide?  (5) What does "highest center point" mean with respect to measuring the height of the bridge -- i.e., isn't there just one center point?  I would have thought what would be measured is the height of the bridge deck at the center, but this seems to suggest it is the highest part of the structure at the center (so for example one could build a straw antenna at the bridge's center point and it would count towards the height)  (6) Can you touch the bridge to stabilize it while you’re in the act of placing the loading object?  (7) Is there any benefit to the bridge holding the weight longer than 10 seconds?  There’s conflicting guidance; one section says "Testing will end when the bridge fails to hold the weight, any part of the bridge sags and touches the tabletop, or the end of ten seconds” suggesting all that matters is if it makes it to 10 seconds.  Another says "The bridge must support the object for one minute, with partial points given for any time above 10 seconds”, suggesting 1 minute is better than 10 seconds  (8) There appears to be conflicting guidance on whether the written test is part of the 25 min "Construction Phase" time (as it says in the title “Construction Phase and Written Test” section header) or part of the “Bridge Testing Phase” (where the first bullet under it says “The students will take a short test on bridge types”)

Answers: (1) The support structures are blocks of wood that raise the bridge off the table enough for the Event Supervisor to watch for the bridge sagging to the tabel top. They are not a part of the team build and may not have the bridge taped to them (2) None. (3) Answered. The bridge will sit on top of blocks of wood. (4) The 6cm rule is for the entire length of the bridge. (5) As stated in the rules: The Event Supervisor will measure and record the height to the nearest millimeter (1mm) at the center point of the bridge. (6) Once the weighted object touches the loading block the team's time begins. Any touching after that is a violation. (7) Self explanatory rule. (8) Students will have written questions to answer during the building phase. These questions make up 25% of the team score.

Question: What is the span of the bridge? Basically how long is the expectation of the bridge. Thanks.

Answer: The bridge must have a width of at least 6 cm, outside edge to outside edge, with any length using the materials provided.

Question: For the bridge building, the suggested bridge width, 6 cm, is larger than the size of the loading block, 5 cm by 5 cm. How does the loading block is placed on the center of deck?

Answer: Stated in the rules. The student place the loading block on their bridge at its center point.

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