Part of the Make Your Own Earthquake series. Students will divide into groups of 3 or 4. Each group will perform three separate experiments using wooden blocks on a shake table to demonstrate how mechanical energy is conserved and transformed. (Note: this activity does not explain how to construct the shake table )
Earth is made of 7 major tectonic plates and numerous secondary and tertiary plates that move towards each other, away from each other or slide past each other. The forces between the plates cause potential energy to be stored along the boundaries. When too much energy is stored along these boundaries, energy is released through the movement of these plates which causes earthquakes. Every year, hundreds of thousands of earthquakes occur along the boundaries of these plates that vary in magnitude and intensity.
Figure 1. World Seismicity Map. Small dots are earthquakes of various depths which help outline the plate borders. Earthquake engineers use shake tables to simulate released energy in order to understand how to help reduce damage and destruction of infrastructure due to natural disasters. Students will assemble into groups of three to create model structures using engineering techniques to control the amount of kinetic energy being transferred from the release of energy from the earthquake, to the infrastructure that is affected.
Figure 2. Shake Table with six story structure
Earthquake Engineering Component
Structural earthquake engineering is an iterative process that strives to improve structural response to earthquake-induced forces. Earthquakes can cause walls to crack, foundations to move or settle, and utilities to rupture and even entire buildings to collapse. In an effort to protect the public and avoid structural damage engineers incorporate into their structural designs techniques that withstand these incredible forces. Some examples include cross bracing, tapered profiles, base isolation and tuned mass damping. In all cases engineers contrive an idea, test it, and then, based on its performance, re-engineer the structure until the desired outcome is achieved.
Learning Objectives and Standards
Links to the National Science Standards and to individual State Science Standards are available by using this link:
- 2 zip-loc bags
- Flat Surface to shake, like table (or see shake table handout)
- 10 wooden blocks ~ (2" x 4" x 7") We used one long block of wood cut into pieces
- 2 nails
- Glue (or molding clay, play-do should work well)
- 8 wooden sticks
As engineers, students will use their shake table to simulate earthquakes on infrastructure using wooden blocks. The steps of this activity, in general will be to plan their structure, build their model, test it on the shake table, then write a report that should be tailored for a potential client. Charge each group for materials. Give them a pricelist of each block, marble etc. Base isolation:
Figure 3. Base Isolation
Students will configure two sets of blocks as they want but both sets must be identical. Have them assess and write about why they chose the configuration.
(follow directions in above photo for construction of base isolation)
- Test both sets of blocks on shake table at various magnitudes of shaking. One structure should be on the base isolation and one should be directly on the shake table. 6Have them answer these questions in their report
- Which set of blocks fell first and why
- How long did it take for the first set of blocks to fall? The second set?
- Use a different configuration, to test your blocks
- Did this set of blocks respond differently? If so, how and why?
- Which set of blocks is releasing more kinetic energy? Why?
- Which set of blocks is storing more potential energy? Why?
- Have them include sketches of their configuration in their report
Figure 4. Mass Damper
- Follow directions for assembling the marbles in the bag and nailing it to the wood.
- Have students use two sets of blocks one with the damper and one without.
- Have them test both blocks on the shake table and follow steps 3 and 4 of Part A.
Figure 5. Cross Bracing
- Have students construct bracing as desired.
- They must have the two sets of blocks constructed identically, except one should have bracing on it
- Have them test both structures on the shake table and repeat steps 3 and 4 of part A
Their final report should include (but not limited to) the following:
- Name of their engineering group
- Table of Contents
- Expenditures/ Cost (see .pdf attachment for example)
- How much was saved?
- Hypothesis on which structure will perform the best under shaking
- Recommendation for construction
- Images of real buildings that use cross bracing, mass damper, and base isolation
- Conclusion ( Summarize thoughts on stored and released energy)
Links and Resources
- NEES Academy: http://nees.org/education/for-teachers/k12-teachers
- Teach Engineering: http://teachengineering.com
- Earthquake Resistance video http://www.youtube.com/watch?v=LwSikXWcGC4
Pre Activity Assessment
- Understanding the problem
- Why do we need to simulate earthquakes
- Societal impact
- Class discussion on energy
- Understanding engineering limitations (time/money/material availability
Activity Embedded Assessment
- Using a stop watch to determine length of time it takes for the blocks to fail
- Determining how energy is being transferred
- Construction of various configurations for each demo
- Team work
Post Activity Assessment
- Real life examples of engineering techniques
- Report writing for client
Researchers should cite this work as follows:
Tenille Denise Medley (2011), "Make Your Own Earthquake: Earthquake Resistant Structure Using Wood Blocks," http://nees.org/resources/2738.