Hands-on Activity: Shake It Up! Engineering for Seismic Waves
Educational Standards :
Pre-Req Knowledge (Return to Contents)
Students should be able to measure length with a ruler, and have an understanding of seismic waves (as provided in the associated lesson).
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
Each group needs:
To share with the entire class:
To build the teacher's shake table (optional):
Introduction/Motivation (Return to Contents)
How many different kinds of waves can you think of? (Listen to student suggestions and add others. For example, electromagnetic [light, radio], sound, ocean [water], seismic, pressure, compression, standing and sine waves.) No matter what kind of wave, what do they have in common? (Draw a wave on the board and identify its parts.) That's right: amplitude, wavelength, crest, trough, frequency.
What types of waves do we associate with earthquakes? That's right, seismic waves. Seismic waves are waves that move through the Earth, and are typically created by earthquakes. For all seismic waves, the amplitude or intensity of the wave is dependent on three things:
The people who work in "earthquake engineering" focus on protecting us and the natural and human-built environments from earthquakes. They want to limit our risk of death and damage from earthquakes. How can we possibly make sure that our school or stadium or a skyscraper or a freeway overpass will not collapse in a big earthquake? Well, engineers create shake tables to test the ability of buildings and other structures to withstand the seismic waves produced by earthquakes. To do this, they carefully design and construct shake tables that can accurately re-enact the ground motion of the Earth during earthquakes. Sometimes they test full-size buildings and sometimes they test small-scale model buildings or components. Some shake tables are large enough to put a real-size building on; others are smaller, even tabletop size. By doing this, engineers can test materials, designs, and construction methods to develop building codes and best practices that provide people living in earthquake-prone areas with safe and survivable surroundings.
Engineers must understand everything about the various seismic waves produced during earthquakes and how they cause the Earth to move. Who can tell me the four types of seismic waves that engineers need to simulate? They are:
What do you know about these different types of seismic waves? How are they different from each other? P-waves and S-waves are body waves, which travel through the body of the Earth. P-waves are the fastest of all the seismic waves and can travel through any medium, although they move through solids faster than through liquids and gases. P-waves vibrate the parallel to Earth or in the direction of their propagation. They are similar to a compression wave moving through a slinky. S-waves are the second fastest type of seismic waves, and they can only move through solids. S-waves are transverse or shear waves and move the Earth perpendicular to the direction of propagation. Both P-waves and S-waves are types of body waves and travel through the interior of the Earth.
Love waves and Rayleigh waves are surface waves, which travel along the surface of the ground. In general, surface waves are slower than body waves—and more destructive. Love waves cause a horizontal shifting of the Earth perpendicular to the wave propagation. Rayleigh waves are a type of sinusoidal wave and move like ocean waves. They are produced by the interaction of P-waves and S-waves. Rayleigh waves are the slowest of all the seismic waves with a speed approximately equal to 3 km/second.
Smart design and testing make buildings resistant to the seismic wave movement of earthquakes. A properly engineered structure does not necessarily have to be extremely strong or expensive, but it must be correctly and intelligently designed to withstand the seismic effects while sustaining an acceptable level of damage. What are your ideas? Let's create our own shaker tables and model buildings to test them.
Vocabulary/Definitions (Return to Contents)
Procedure (Return to Contents)
Before the Activity
With the Students
(Note to teacher: If students need more clarification of the movement generated by the four seismic wave types, refer to the PowerPoint presentation in the associated lesson. Tips: It is a challenge to make the student shake tables really replicate all four wave movements; it is easiest to focus on the P-waves and surface waves. To replicate P-waves, students must find ways to move the board back and forth along a horizontal plane. To replicate surface waves, students must find ways to move the board in a more up-and-down, lopsided fashion. Placing marbles under a board enable it to slide back and forth, and using different-sized marbles generates a more "surface wave" type motion. To control the shake tables, it helps to cut access holes in the sides of the box, and/or adhere string or Popsicle sticks to the box and its components.)
Attachments (Return to Contents)
Safety Issues (Return to Contents)
Troubleshooting Tips (Return to Contents)
Make sure students test, revise and improve the integrity of their structures using their own shake tables. If this is not emphasized, students may just build a shake table and a structure, and move directly to the "real earthquake" without the learning that comes from the testing/redesign cycle.
Investigating Questions (Return to Contents)
(Note: These questions are included on the worksheet as part of the post-activity assessment.)
Assessment (Return to Contents)
Design Section of the Worksheet : As either pre-activity homework or the first task of the activity, assign students to complete their own designs for shake tables and model building structures, including drawings, measurements, material specifications and explanations of how the designs function. Require that students describe which types of seismic waves their shake tables will produce and how those types of seismic waves move the Earth.
Activity Embedded Assessment
Observations and Questioning: During the activity, move around the classroom to observe students and ask them questions about what they are doing to determine how well they understand the activity. Ask individual students to explain what the group is working on, their strategies, what type of seismic waves their shake table creates, etc.
Conclusion Section of the Worksheet and Class Discussion: Review students' answers to the Shake It Up! Worksheet questions to gain an understanding of why they think certain structures performed better than others. See whether or not students thought the ability of their shake tables to accurately represent seismic waves helped in the evolution of their building designs. Explore the questions in a class discussion format so that students can hear each others' opinions and ideas (see the Investigating Questions section).
Activity Extensions (Return to Contents)
Now that students have completed their own trial and error experimenting, have them research the real-world design and construction strategies being used to make earthquake-resistant structures. Have students investigate and report back to class on earthquake engineering strategies for both new and existing structures of all types. Start by researching seismic base isolation, seismic vibration control and earthquake-resistant construction.
Activity Scaling (Return to Contents)
Additional Multimedia Support (Return to Contents)
For good descriptions and drawings of seismic waves types, see Michigan Tech's UPSeis web page at http://www.geo.mtu.edu/UPSeis/waves.html
Find more information on earthquakes, earthquake engineering, earthquake shaking table, Love wave, P-wave, Rayleigh wave, S-wave, seismic wave, and wave at http://en.wikipedia.org
Show students a 43-second video showing a comparative test of two 12-floor model towers under earthquake simulation, one with seismic base isolation in place and one without. See Earthquake Protector: Shake Table Crash Testing at http://www.youtube.com/watch?v=kzVvd4Dk6sw&feature=related
References (Return to Contents)
World's Largest Earthquake Shake Table Test in Japan. Simpson Strong-Tie Company, Inc. Accessed April 20, 2011. (Article and a five-minute video show a full-scale seven-story wood-framed condominium tower being tested on world's largest shake table in July 2009, where it survived a 7.5 magnitude earthquake simulation with minor damage) http://www.strongtie.com/about/research/capstone.html?source=hpnav
ContributorsCarleigh Samson, Stephanie Rivale, Denise W. Carlson
Copyright© 2010 by Regents of the University of Colorado
This digital library content was developed by the Integrated Teaching and Learning Program with funding from the Gates Frontiers Fund.
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Last Modified: March 7, 2014