Structures and Mechanics with fischertechnik Building Bridges – Level 2

1. Structures and Mechanics with fischertechnik Building Bridges – Level 2

2. What You’ll Learn… • How different types of bridges are engineered • How bridges are designed with trusses for support • The effect of compression and tension forces in different types of bridge designs • How to use the fischertechnik construction system to model bridge design Stuff You’ll Need… • Fischertechnik Profi Mechanic + Static Set • Mechanic + Static Activity Booklet • Mechanic + Static Assembly Instruction • Digital camera

3. ePortfolio Suggestions… • Before you begin the activities in this Learning Launcher, write down anything you already know about bridge design and construction. • List three interesting things you learned from the What You Should Know… section. • Keep a glossary of new words you learn. Pay particular attention to the bold, italicized words you find. • Take pictures of each of your fischertechnik bridges and label each of the parts. • Take a picture of one or more of your bridges and diagram where you think compression and tension forces might be. • Discuss where each of the bridges might be used. • Answer each of the questions in the Activity Booklet. Record your observations in your Project Planner. • Take pictures of real bridges or find them on the internet and compare them to your models.

4. What You Should Know… • You should already be familiar with the fischertechnik construction system. • You should understand the basic principles of statics. • You should understand why triangle shapes are commonly used when engineering structures. If you are not familiar with any of these concepts, you should review the What You Should Know… section of the Level 1 World of Statics Learning Launcher.

5. What You ShouldKnow… Getting to know fischertechnik… fischertechnik is a precision modeling system designed and produced in Germany. Like many modeling systems, fischertechnik is a great way to model structures and machines on a small scale. Unlike many modeling systems, fischertechnik is the choice of scientists and engineers for sophisticated modeling simulations and experiments. fischertechnik can be used to model large structures and simulate complex machines. With its sensors and computer programming capabilities, fischertechnik is even a sophisticated robotics system. If you have not worked with fischertechnik before, take the next 15 minutes and explore your fischertechnik Mechanic + Static collection. If you have worked with fischertechnik before, proceed to the next slide.

6. What You Should Know… Bridges • The purpose of a bridge is to get people and their belongings from one side of an expanse to the other. The expanse can be a landform like a valley or crevasse, a street, a body of water, or any other depression or obstacle. • People may walk or use another form of transportation including bicycles, cars, trains, wheelchairs, busses or the like. • There are many different kinds of bridges. Each type is used for a different situation, depending on the distance, object(s) to go across, the materials available, the access to the expanse, and need for the bridge over time.

7. What You Should Know… • Bridge types generally fall into four categories Beam Truss Suspension Arch • Beam Bridge • This is a single beam across a span supported by piers. Piers can be used at points in the middle of the span between the end piers. Beam bridges are simple to construct but not very rigid. For this reason they aren’t generally used for spans greater than about 250 feet.

8. What You Should Know… • Truss Bridge • A truss bridge uses structural members called trusses to add strength. Trusses can be used to strengthen arch and suspension bridges too. For that reason, some bridge experts would classify the bridge at right as a beam bridge with trusses. If you research bridges online, you’ll find that different experts classify bridges different ways! • Trusses are usually constructed in triangle shapes. Can you think why? • Trusses can sometimes be quite complex, like in the bridge shown at left. This is a special kind of truss bridge called a cantilever bridge.

9. What You Should Know… • Suspension • In this complex structure, thebridge bed or deck is suspended by cables. • Arch These bridges offer naturalstrength by redirecting much of the downward pressure outwards. Though very unstable until the spans are actually connected, arch bridges have withstood the “span” of time.

10. What You Should Know… • Other types of bridges are variations of the three main categories. • Cantilever • Moon • Girder • Clapper • Pontoon • Stone • Trestle • Transporter • Covered

11. What You Should Know… • Look closely at these three bridges. What do they have in common? • What type of bridge is each of these? Beam, truss, suspension, or arch?

12. What You Should Know… • Did you notice that all three bridges are constructed using triangle shapes? These triangle-shaped sections are called trusses. Trusses are a framework of beams forming a rigid structure. • In construction and architecture, the triangle is commonly used because it is the simplest geometric shape that will cannot change shape when the sides are a fixed length. If this concept is unclear to you, look at the What You Should Know… section of The World of Statics Learning Launcher for a demonstration.

13. What You Should Know… There are two forces at play in all bridges. Compression is a force that compresses or shortens the object it is acting on. Tension is a force that stretches or lengthens the object it is acting on. Imagine a spring. When you pull it apart, you create tension. If you don’t stop pulling on it, eventually it will snap back. When you push it together, you create compression. If you don’t stop pushing on it, eventually it will buckle. Compression Tension

14. What You Should Know… Piers Anchorage Anchorage Piers Beam Suspension Arch Red represents compression. Blue represents tension

15. Do It! Building Bridges… Now that you know a little about how bridges are engineered, it’s time to try building a few to see how they perform! Find the Activity Booklet in your Mechanic + Static kit. Turn to page 37 and build the Girder Bridge as shown. You can find assembly instructions on page 92 of the Assembly Instruction book. Your book calls it a “girder” bridge because it would likely be built using steel girders. Using the terms in this Learning Launcher identify the type of bridge structure this represents. Be sure to answer the questions in the Activity Guide and record your answers in your Project Planner! Assembly Instruction Activity Booklet

16. Do It! Building Bridges… Next, build the Bridge with Underbeam on page 38 of the Activity Booklet in your Mechanic + Static kit. You can find assembly instructions on page 94 of the Assembly Instruction book. Using the terms in this Learning Launcher, what kind of bridge is this? Answer the questions in the “Your Task” section of the Activity Booklet. Be sure to record your observations in your Project Planner.

17. Do It! Building Bridges… Next we will build the build the Bridge with Upperbeam on page 38 of the Activity Booklet in your Mechanic + Static kit. As you can see, it is very similar to the Bridge with Underbeam you just built. Before you build it, make a prediction about how this bridge will perform compared to the previous bridge and record it in your project planner. Now, go ahead and build your bridge. You can find assembly instructions on page 96 of the Assembly Instruction book. Answer the questions in the “Your Task” section of the Activity Booklet. Be sure to record your observations in your Project Planner.

18. Do It! Building Bridges… What did you observe about the upperbeam bridge compared to the underbeam bridge? Can you explain why one bridge might have performed better than the other? Think about where compression and tension forces might be for each bridge design. What conclusions can you draw about each type of force and what it means for bridge design.

19. Build a bridge of your own design using what you’ve learned about bridge engineering. Try building some of the other structures in the Mechanic + Static Assembly Instruction book. Or design one of your own. Try building one of the mechanical devices in the Mechanic + Static Assembly Instruction book. Take a photograph of a bridge in your area or find one on the internet. Can you find structural elements similar to the models you just built? Go online and search for “fischertechnik projects”. Check out some of the amazing things people have built using this sophisticated modeling system. Extend Yourself…

20. Find a famous bridge online. What kind of bridge is it? How do you thinkit is designed to handle the forces of tension and compression. Find a video of the Narrows Bridge in Tacoma, Washington online. Why did it collapse? How are bridges designed differently today to avoid the same problem? In this Learning Launcher, we learned that trusses make beam bridges stronger. This same principle is used in the design of other objects. HINT: Look at the edge of a piece of corrugated cardboard (like is used in a shipping box). Where else can you find this design principle? In this Learning Launcher, we learned that arches are a strong natural shape. Where do you find this shape adding strength in nature? Synchronous lateral excitation is a mouthful! Research the Millennium Bridge in London to find out what it is and the problems it caused in that modern footbridge design. Extend Yourself…