Unit D Lesson D10 Structural Components
Completion requirements
Lesson D10: Structural Components
Video Lesson
Humans want structures to last a long time. Watch this video to learn more about shapes and design features used to build strong structures.
Lesson D10: Structural Components
Figure D.2.10.1 – The Montreal Biosphere was built for the 1967 World Fair Expo.
Figure D.2.10.2 – This geodesic dome is in the Epcot Center at Walt Disney World in Florida, USA.
Geodesic Domes
A geodesic dome, such as the one seen in Figures D.2.10.1 and D.2.10.2, is a sphere or half-sphere made of triangles.
A geodesic dome is a very strong structure because it contains both triangles and a dome (arch). Triangles and domes help transfer the compression force from a load evenly over the entire structure.
From 1975 to 2003, the research station at the South Pole was a geodesic dome (Figure D.2.10.3). The South Pole often has strong winds and blizzards, which a geodesic dome could withstand.
A geodesic dome, such as the one seen in Figures D.2.10.1 and D.2.10.2, is a sphere or half-sphere made of triangles.
A geodesic dome is a very strong structure because it contains both triangles and a dome (arch). Triangles and domes help transfer the compression force from a load evenly over the entire structure.
From 1975 to 2003, the research station at the South Pole was a geodesic dome (Figure D.2.10.3). The South Pole often has strong winds and blizzards, which a geodesic dome could withstand.
Reading and Materials for This Lesson
Science in Action 7
Materials:
Science in Action 7
Reading: Pages 300–303
Materials:
wooden blocks, construction paper, coins, 65 plastic straws, masking or cellophane tape, permanent marker, ruler, scissors
Figure D.2.10.3 – A geodesic dome is well-suited for harsh polar conditions.
Try It!
Build a Miniature Geodesic Dome
Try building your own little geodesic dome!
Materials:
- 65 plastic straws
- masking or cellophane tape
- permanent marker
- ruler
- scissors
Instructions:
- Cut 30 straws 8.2 cm long. With permanent marker, mark a long line on these straws. The long line indicates that these are "A" straws.
- Cut 35 straws 9.3 cm long. These are "B" straws.
- Follow the diagram in Figure D.2.10.4 to connect your straws. Use small pieces of tape to connect your straws at the corners.
- Begin by taping together a circle of 10 B straws to form the base of the geodesic dome.
- Tape one A straw and one B straw to each corner (where the 10 B straws are joined together) of the base.
- Connect the tips of two A straws together to form a triangle. Repeat for all the other A straws. You should have 5 triangles.
- Repeat step 6, using A straws.
- Tape 10 A straws together to make another ring of straws. Tape the corners of this ring to the triangle tips you made in steps 6 and 7.
- At the five corners that have only A straws, connect 1 more A straw. At the 5 corners that are connected to B straws, connect 2 more B straws.
- Bring the B straws on either side of an A straw together. Three straws will be touching. Tape them together. Repeat this five more times around the dome.
- Tape 5 A straws together to form a star. Tape a B straw between each point of the star, forming a pentagon with a star inside.
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Tape the corners of the pentagon to the remaining open corners of the dome.
Figure D.2.10.4 – Geodesic dome instructions.
Challenge: Test Your Geodesic Dome!
Now that you have built a miniature geodesic dome, you should try testing how strong it is! Think of a safe, fair method of testing your dome. Then, go ahead and test it! When you have completed testing, ask yourself – "How would I change the way the geodesic dome is built to make it stronger?"
Now that you have built a miniature geodesic dome, you should try testing how strong it is! Think of a safe, fair method of testing your dome. Then, go ahead and test it! When you have completed testing, ask yourself – "How would I change the way the geodesic dome is built to make it stronger?"
Try It!
Build the Strongest Bridge
What shapes make strong bridges?
Try building three different bridges and test which is the strongest.
Materials:
What shapes make strong bridges?
Try building three different bridges and test which is the strongest.
Materials:
- wooden blocks or heavy books (something to support the ends of your bridges)
- construction paper
- coins (preferably all the same type)
- scissors
Instructions:
The following video shows examples of the bridges built in steps 1, 2, and 3.
The following video shows examples of the bridges built in steps 1, 2, and 3.
- Beam Bridge: Set up two towers of wooden blocks to support the bridge. Cut a piece of construction paper in half lengthwise. Lay this strip of construction paper from one bridge supports the other to make the bridge deck.
- Arch Bridge: Set up two towers of wooden blocks to support the bridge. Cut a piece of construction paper in half lengthwise. Curve one half of the construction paper into an arch shape. Put the arch between the two towers. Lay the other half of the construction paper on top of the arch and wooden blocks to make the bridge deck.
- Truss Bridge: Set up two towers of wooden blocks to support the bridge. Fold one full sheet of construction paper lengthwise in accordion style (zig-zag folds). Lay the accordion-folded construction paper across the two bridge supports. Lay a half sheet of construction paper on top of the folded paper to be the bridge deck.
- Add coins, one at a time, to the middle of the beam bridge deck. Keep adding coins until the bridge collapses. Write down the number of coins the bridge was able to hold.
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Add coins one at a time to the arch and truss bridge decks. Keep the coin type the same when testing the bridges so that the test is fair.
Questions:
Think about the following questions very carefully. Then, type or write your answers. When you have your answers, click the questions for feedback.
Think about the following questions very carefully. Then, type or write your answers. When you have your answers, click the questions for feedback.
The truss bridge held the most coins. The accordion-folded paper under the bridge deck formed triangles. Triangular shapes are strong because they spread the load by transferring the load down the sides of the triangle.
The beam bridge held the least coins. The beam bridge bent easily from the load of the coins because it did not have any additional supporting shapes or structures.
Triangles and arches make a bridge design strong.
Strong Old Shapes
Hundreds and even thousands of years ago, humans determined how to use strong shapes in the structures they built. Two thousand years ago, the ancient Romans used arches in bridges and buildings.
An arch bridge was built 1400 years ago in China. This bridge has lasted through many wars, floods, and earthquakes.
Figure D.2.10.6 – This Roman bridge in France carried water to a town; it still stands today.
Make sure you have understood everything in this lesson. Use the Self-Check below, and the Self-Check & Lesson Review Tips to
guide your learning.
Unit D Lesson 10 Self-Check
Instructions
Complete the following 6 steps.
Don't skip steps – if you do them in order, you will confirm your
understanding of this lesson and create a study bank for the future.
- DOWNLOAD the self-check quiz by clicking here.
- ANSWER all the questions on the downloaded quiz in the spaces provided. Think carefully before typing your answers. Review this lesson if you need to. Save your quiz when you are done.
- COMPARE your answers with the suggested "Self-Check Quiz Answers" below. WAIT! You didn't skip step 2, did you? It's very important to carefully write out your own answers before checking the suggested answers.
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REVISE your quiz answers if you need to. If you answered all the questions correctly, you can skip this step. Revise means to change, fix, and add extra notes if you need to. This quiz is NOT FOR MARKS, so it is perfectly OK to correct
any mistakes you made. This will make your self-check quiz an excellent study tool you can use later.
- SAVE your quiz to a folder on your computer, or to your Private Files. That way you will know where it is for later studying.
- CHECK with your teacher if you need to. If after completing all these steps you are still not sure about the questions or your answers, you should ask for more feedback from your teacher. To do this, post in the Course Questions Forum, or send your teacher an email. In either case, attach your completed quiz and ask; "Can you look at this quiz and give me some feedback please?" They will be happy to help you!
Self-Check Time!
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Self-Check Quiz Answers
Click each of the suggested answers below, and carefully compare your answers to the suggested answers.
If you have not done the quiz yet – STOP – and go back to step 1 above. Do not look at the answers without first trying the questions.
A triangular roof allows snow to slide from the roof, reducing the load on the roof. The compression force from any snow on the roof transfers down the triangle to the lower part of the building. If the house had a flat roof, the roof would
bend and collapse more easily from the load of the snow.
This structure has a dome. Domes spread the force from the load of a structure, which makes the structure more stable. Domes are actually complex arches.
This is an arch. The load from the person standing on the arch is transferred down through both sides of the arch, supporting the person and keeping the arch standing.
The outside of this building has many triangles in a grid. The load of the tall building can be spread and transferred over all these triangles.
The railroad bridge has triangular shapes in its trusses. Triangles do not bend easily from the shearing force of heavy winds.