Shaking Buildings

Resonance, soil and protection

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Buildings have natural periods of about 0.1 s per storey.
• Ground shaking near that period makes them resonate; soft soils amplify certain periods.
• Base isolation and good foundations reduce the danger.

Steps

1. Buildings sway too
2. Mexico City, 1985
3. Sideways force
4. Base isolation
5. A rule of thumb
6. Ground turning to liquid