Activity: Build an Earthquake-proof Structure
Update 9/28/17: MyScienceBox no longer is active. TeachEngineering’s Earthquake in the Classroom offers a standards-based, teacher-tested alternative.
(Activity courtesy of MyScienceBox and Irene Salter).
Level: Grades 6-12.
Time Required: Three class sessions: 1) to build the shake table (may be prepared ahead of time) and make preparations; 2) to build the tower structures; and 3) to test each structure.
Group size: 2-4 students. Teacher handout: project_quake_towers.doc
Earthquake-proof Structures
Students in grades 6-12 construct towers out of drinking straws that must withstand simulated earthquakes vibrations and the increasing load of 250 gram sandbags. After each test, students have 2 minutes to repair any damage before the next begins. Students learn basic principles of earthquake engineering and design, as well as team skills essential to all fields of science and engineering.
Objectives
Students will:
- understand basic principles of earthquake engineering and design including the importance of a solid foundation, wide base, symmetrical design, and trusses.
- work together in a team to design and build a structure.
- follow through a design process of repeated designing, testing, redesigning and retesting a structure.
Standards
Grade 6 – Earth Science
Plate Tectonics and Earth’s Structure
1. Plate tectonics accounts for important features of Earth’s surface and major geologic events. As a basis for understanding this concept:
d. Students know that earthquakes are sudden motions along breaks in the crust called faults and that volcanoes and fissures are locations where magma reaches the surface.
e. Students know major geologic events, such as earthquakes, volcanic eruptions, and mountain building, result from plate motions.
Shaping Earth’s Surface
2. Topography is reshaped by the weathering of rock and soil and by the transportation and deposition of sediment. As a basis for understanding this concept:
d. Students know earthquakes, volcanic eruptions, landslides, and floods change human and wildlife habitats.
Vocabulary
- Foundation
- Height-base ratio
- Symmetry
- Truss
Materials
Attachments:
For the entire class:
- 10-20 sandbags consisting of 250 grams sand in a sandwich sized ziplock bag. The bag should be taped into a sausage shaped cylinder for rigidity and ease of mounting onto the towers.
- 1 earthquake tower testing platform with a movable platform connected to a rigid frame by rubber bands, springs, or a motor. Several designs may be found in the Sources section.
- 4 large binder clips to secure the cardboard bases to the shake table platform.
For each group:
- 1 cardboard base (approximately 25 cm by 25 cm)
- 30 straws
- 100 paper clips (one box)
- 20 straight pins
- 2 meters of string
Prerequisite knowledge
None, although the activity fits well with a seismology lesson.
Procedure
Getting Ready
1. Build the earthquake shake table as described below. This is an activity that might be done with the entire class, depending upon its size and the age of the students; or, teachers may wish to prepare it ahead of time. See the MyScienceBox Sources section for more help.
2. Do a trial run with a structure of your own design to see where students may run into trouble (two possible problem areas include securing the structure to the foundation and securing the joints).
3. Have the students help prepare 10-20 sandbags consisting of 250 grams sand in a sandwich-sized ziplock bag. Each bag should be taped into a sausage shaped cylinder for rigidity and ease of mounting onto the towers.
With the Students
1. Divide students into small working groups. Distribute the student handout, explaining the rules and requirements of this building challenge.
2. Demonstrate the testing procedures and show how the shake table works.
3. Show students some of the different methods for joining straws together without folding the straws and compromising their integrity.
- Two straws may be pinned together with a straight pin.
- A paper clip may be partly opened up – the inner U pulled out from the outer U – and each U may be slipped into a different straw.
- Holes may be drilled with the pins and the string slipped through to tie straws together.
4. Allow students to begin designing and building.
5. Pause the class once or twice a class period for 5 minute “teaching commercials” to point out various successful student designs or to combat problems multiple teams may have encountered. Some pointers and discussion may include:
- Strategies for how to secure the structure to the foundation using paper clips, pins and/or string.
- A description of trusses and cross-bracing and discussion of their use in bridges, earthquake retrofitting, and other structural engineering.
- Would a better structure have a wide base of a narrow base?
- Would a better structure be symmetrical or asymmertrical?
- How can you secure the sand bags so that they don’t fall off?
6. Once students have built their structures, have them answer the structural analysis questions posed on the towers handout:
- During construction, how did you test the strength and stability of your structure?
- During construction, what strategies did you use to strengthen the weaker areas? Why?
- What are the strongest parts of your building? Why?
- What are the weakest parts of your building? Why?
- Where did you use string in your structure? Why?
- Where did you use pins in your structure? Why?
- If you had 5 more straws, where would you add them? Why?
7. Test the structures. To save time, teachers may have the groups test their structures as they finish, which also allows work to proceed at a varying pace. Or, all teams can finish building on the same day, with testing taking place on the next day. In this way, the students can watch others and make observations, noting what worked and what didn’t.
Extensions
Once all groups have tested their structures and compared various strategies, challenges, and successes and failures, allow them to refine their designs, then conduct a second test. Remind them that structural engineers continually test and improve their designs for better results.
Have students find and examine reports of recent earthquakes, such as our eGFI story on the 2010 Haiti disaster. Have them discuss what important structural failings were involved. How have engineers gotten involved to assess damages and address the problems? Students could also seek out information on engineering innovations designed to strengthen buildings or aid in disasters.
Building the Shake Table
To create your own very simple earthquake table that is more like a trampoline than a standard, motor controlled earthquake table:
- Cut a piece of board or plywood into a 12” square. If you wish, create a raised edge for your platform by nailing lengths of 1/2” square dowel on top of each of the sides.
- Mount wood screws on the under side of the plywood at each corner and at the center of each side. Don’t screw the screws in all the way, make sure at least 1/4” sticks up so you can loop a rubber band around it.
- Construct a frame out of 2” x 4”s that fits around the wood square with around 1/2” clearance between the outer edge of the square and the inside edge of the frame. Make sure the 2” x 4”s are oriented so that the frame is 4” high.
- Mount wood screws on the top edge of the frame at each corner and at the center of each side. Again, don’t screw in the screws all the way.
- Loop a rubber band around each pair of screws so that the plywood square is suspended like a trampoline within the frame.
Student Handout: Earthquake Tower Challenge
(from the Student handout)
You and your partner have been hired as the structural engineers in charge of designing a new 2-story art building. There are many building codes you must follow. Each floor of the building must support at least 250 grams of weight. Also, the building will be located near an earthquake fault; therefore your building must be able to withstand both small and large earthquakes. Since the building will be used for art classes, you may be as creative as you like with the shape and design of the building (it does not need to be box shaped).
You are limited to the following materials:
- 1 cardboard base (approximately 25 cm by 25 cm)
- 30 straws
- 100 paper clips (one box)
- 20 pins
- 2 meters of string
Your building must meet the following requirements:
- The building must fit on the base. Attach your building to the base using pins, paper clips, or string.
- Your building must be at least 36 cm tall.
- Your building has 2 stories that are each at least 18 cm tall (approximately the height of 1 straw).
- Each story must support the weight of at least 1 sand bag (250 grams) without collapsing.
- A construction drawing with measurements and analysis must be submitted before earthquake testing.
- To survive an earthquake test, the building must not collapse for 10 seconds after the earthquake begins. The weights must stay on the building. You have 1 minute to repair any damage to your building before the next earthquake test.
Hints and tips:
- PLAN CAREFULLY! Additional supplies will not be provided.
- Remember these words of wisdom: “Measure twice. Cut once.”
- Use the concepts of tension and compression. If an element is in tension and not compression, you can use string instead of straws.
- Try building without pins first, then add pins where connections need reinforcement.
- Make sure that your foundation is very strong.
- Remember to design a way to secure the weights so that they don’t fall off AND so you can add additional weights to the top story.
If you test your building before the final deadline, you may start over from scratch with new materials to try to win the bonus points. However, you will not be able to make up points that you lost with your first building. Therefore, do your best with your first building, but if you earthquake test your building before the deadline, then you will have a second chance to win the bonus points.
Testing and Evaluating the Structures
Grading rubric: the structures must meet the following requirements:
- The building must fit on the base.
- The building must be at least 36 cm tall.
- The building must have 2 stories that are each at least 18 cm tall (approximately the height of 1 straw).
- Each story must support the weight of at least 1 sand bag (250 grams) without collapsing.
- A construction drawing with measurements and analysis must be submitted before earthquake testing.
- To survive an earthquake test, the building must not collapse for 10 seconds after the earthquake begins. The weights must stay on the building.
10 points – Building supports 1 sand bag on the first story.
10 points – Building supports 1 sand bag on the top story.
10 points – A clear, detailed construction sketch was completed. Straws and string should be easily distinguished. All important design features and all critical measurements should be labeled on the sketch.
20 points – A structural analysis of your building was completed. The following questions should be answered clearly and completely:
- During construction, how did you test the strength and stability of your structure?
- During construction, what strategies did you use to strengthen the weaker areas? Why?
- What are the strongest parts of your building? Why?
- What are the weakest parts of your building? Why?
- Where did you use string in your structure? Why?
- Where did you use pins in your structure? Why?
- If you had 5 more straws, where would you add them? Why?
5 points – Building remains standing with 1 sand bag on the top story and 1 sand bag on the first story after a major earthquake.
5 points – Building remains standing with 2 sand bags on the top story and 1 sand bag on the first story after a major earthquake.
5 points – Building remains standing with 2 sand bags on the top story and 2 sand bags on the first story after a major earthquake.
Bonus: The building in each class that can hold the most weight and remain standing after a major earthquake will be awarded 20 bonus points.
Observing the structure: If at any point the structure buckles to the point that the sandbags fall off or drop by more than halfway to the ground (a sandbag on the first story 18 cm high can fall as much as 9 cm and still be considered passing while a sandbag on the second story 36 cm off the ground can fall 18 cm), the structure should be considered to have failed that stage of testing. Students should be given 2 minutes to repair any damage to their structure between each stage of testing although no new straws or materials could be provided. The best structure in the class will likely survive until it encounters a major earthquake with 4 sandbags on the top story and 3 sandbags on the first story.
Testing levels:
Level 1. Place 1 sandbag on the first story.
Level 2. Place 1 sandbag on the second story.
Level 3. Minor earthquake with 1 sandbag on the top story. Move the platform horizontally, side to side so that it touches the frame. No vertical motion is involved.
Level 4. Major earthquake with 1 sandbag on the top story. Move one corner of the platform so that it touches the corner of the frame, as well as the table below, to start a major earthquake and lead to both horizontal and vertical motion.
Level 5. Major earthquake with 1 sandbag on the top story and 1 sandbag on the first story.
Level 6. Major earthquake with 2 sandbags on the top story and 1 sandbag on the first story.
Level 7. Major earthquake with 2 sandbags on the top story and 2 sandbags on the first story.
Level 8. Continue major earthquakes adding 1 sandbag at a time, first to the top story, then to the first story.
Resources
- Explore eGFI articles and videos related to Earthquake engineering on the eGFI students’ blog.
- See other eGFI building lesson plans and activities:
- Other earthquake table designs powered by an electric drill are described by John Lahr.
- A resource on structural engineering principles with projects that can be adapted for the classroom is the book The Art of Construction: Projects and Principles for Beginning Engineers and Architects by Mario Salvadori, Chicago Review Press (1981).
This is a MyScienceBox Lesson Plan by Irene Salter (http://www.mysciencebox.org), licensed under the Creative Commons Attribution-NonCommercial License.
Filed under: Class Activities, Grades 6-8, Grades 6-8, Grades 9-12, Grades 9-12, Lesson Plans
Tags: Building Design, Civil Engineering, Class Activities, Engineering Design Process, Lesson Plans, Safety engineering
