Shaking BuildingsMulti-storey shear-building models under earthquake ground motion

Ground motion

Source

Magnitude

Distance

Soil

Dominant freq

Duration

Table stroke

Auto sine

Speed

Drift exaggeration

Cracks & damage Un-shaken outline

0 % drift0.6 %1.2 %+ story drift

Resonance. Each building has a natural period T₁ (about 0.1 s per storey). Where it sits on the response-spectrum curve decides how hard it is shaken: tall buildings love long-period shaking, low-rise ones short.
Mexico-City preset. Soft basin soil rings at about 0.5 Hz (2 s). The 20-storey tower resonates with it while the stiff low-rise buildings barely notice.
Pulse preset. A single ~1 s velocity pulse (near-fault) is devastating for mid-rise buildings whose T₁ is close to the pulse period.
Soft storey. The 5-storey building with a weak open ground floor concentrates all drift in one storey, which yields and can collapse while the floors above stay nearly rigid.
Base isolation. The isolated 8-storey sits on soft bearings (T about 2.4 s): the ground moves, the building barely does. Watch its drift stay near zero, until the moat wall is hit.
Tuned mass damper. Compare the two 20-storey towers under the sweep or Mexico preset: the roof mass out-of-phase motion cuts the sway.
Shake table. Set the frequency to a building's 1/T₁ and watch only that one blow up. Or drag the ground yourself.