Most cantilever bridges use two cantilever arms extending from opposite sides of the obstacle to be crossed, meeting at the center. However, in a cable-stayed bridge, less cable is required and the towers holding the cables are proportionately shorter.Ĭantilever bridges are built using cantilevers - horizontal beams that are supported on only one end. Like suspension bridges, cable-stayed bridges are held up by cables. Weight on top of the beam pushes straight down on the piers at either end of the bridge. In modern times, beam bridges are large box steel girder bridges. The earliest beam bridges were simple logs that sat across streams and similar simple structures. The weight of the bridge is thrusted into the abutments at either side.īeam bridges are horizontal beams supported at each end by piers. The earliest known arch bridges were built by the Greeks and include the Arkadiko Bridge. There are six main types of bridges: arch, beam, cable-stayed, cantilever, suspension, and truss.Īrch bridges are arch-shaped and have abutments at each end. What sort of trade-offs do you think engineers make between functionality, safety, and aesthetics when building a real bridge?.Do you think you would have been able to complete this project easier if you were working alone? Explain….What designs or methods did you see other teams try that you thought worked well?.If you had to do it all over again, how would your planned design change? Why?.Do you think that engineers have to adapt their original plans during the construction of systems or products? Why might they?.What was the average aesthetic score for your bridge? How did this compare to the rest of the class? What design elements of other bridges did you like the best?.How many popsicle sticks did you end up using? Did this number differ from your plan? If so, what changed?.Did you decide to revise your original design while in the construction phase? Why?.Did you succeed in creating a bridge that held the required weight for a full minute? If not, why did it fail?.Student Reflection (engineering notebook) Remember to keep safety in mind, if you try this variation.Design and build a bridge out of popsicle sticks and glue that can hold the weight of:.For more content on the topic, see the “Real World Applications” and “Digging Deeper” sections.As a class, discuss the student reflection questions.Teams should document the amount of weight their bridge could hold and the number of popsicle sticks used.Place the predetermined weight on the bridge for one full minute. Test the bridge designs by suspending or taping the bridge 1 foot above the floor on top of the chairs/desks.They agree on materials they will need, write/draw their plan, and present their plan to the class. Students meet and develop a plan for their bridge.If they are struggling, ask questions that will lead them to a solution quicker. (Give students regular “time checks” so they stay on task. Use a timer or an on-line stopwatch (count down feature) to ensure you keep on time.Announce the amount of time they have to design and build (1 hour recommended).The bridge must be able to hold a pre-determined weight 5 pounds or 20 pounds Structure must span a minimum of 14 inches in length. Įxplain that students must develop a popsicle bridge from 200 popsicle sticks and glue. Give 1 positive comment and 1 suggestion for improvement for each design.Use a scale of 1-5, with 1 being “not at all appealing,” and 5 being “very appealing.”.Next, judge each bridge design for its aesthetic value.Develop a list of attributes in preparation for the judging.As a class, discuss what makes a bridge aesthetically pleasing. ![]() However, it’s fun to keep adding weight to the structure to meet the critical load resulting in a crumbling bridge!
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