Earthquake Tower Design (Rob Vondrak)

Materials needed

Earthquake simulation table (Pitsco EQ table) (Pitsco myQuake)

1/8"x1/8"x36" balsa wood beams

1/4"x1/4"x36" balsa wood beams

1/16"x3"x36" balsa wood sheets

hot glue & glue guns

Camera & Video analysis software

Constraints

• The building must be at least 8 stories tall (48 cm)

• Each floor is 6 cm tall with an area of 6 cm x 6 cm

• The building cannot go over budget (set by the teacher)

• Building must hold a simulated weight on each floor

Procedure

Baseline Test

Students have to get some baseline data for a basic building design. They should create a building that uses 1/8"x1/8" beams for the corners. Then load each floor with 2 washers for a simulated living weight. Attach the tower to the earthquake simulator and start the motor. Slowly increase the speed of the motor/simulator until the building really begins to shake (do not assume the highest speed = the most shaking). Record the tower shaking with your phone. Then use video analysis software to measure the acceleration of the top. That is the acceleration the students must "beat". The goal is to design a building that will have a smaller acceleration than the basic tower.

Research Solutions

Students should research various design features that are used to minimize the damage from earthquakes. Have a class discussion where students share what they have found. As a class, decide which features they should try and have the students build new towers incorporating only one of the new features. Possible features could be using thicker beams, horizontal cross-bracing, X cross-bracing, V cross-bracing, adding a large mass to the top or middle of the building.

Test Possible Solutions

Have the students test the new buildings and measure the acceleration at the point of strongest shaking. Have the class share the results and discuss what design features worked well and which did not.

Design a New Building

Using what was learned from the previous tests and class discussion, students design a new building using any combination of the researched techniques. The building must not go over budget. After getting the design approved by the teacher, students can build the new tower. Students will again test the buildings and measure the acceleration at the point of strongest shaking. If students do not lower the acceleration below the baseline, they should be allowed to make adjustments to the design (again, they must not go over budget).

Questions

• Why did we have to test each possible solution by itself?

  • We needed to know the effects of the possible solution. If we included multiple solutions into our design right away, we wouldn't have know which solution had an effect on the acceleration.

• Why did we have to research ideas before designing our new building?

  • Engineers don't just use trial and error to find the best solution. They need somewhere to start from, so they research ideas that could work to give them a starting point. There may be some trial and error work from there, but at least the research has given them some idea of what to expect.

• What architectural shapes seem to be the most stable?

  • Triangles are usually more rigid than squares. Incorporating more triangular shapes into your building should make it more stable.

Photos

A sample building with washers added as weight to simulate people living in the building.