SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/eng-seismic-inertia-load

Why does a heavier structure generally develop more earthquake inertia force at the same acceleration?

Because inertia force follows force equals mass times acceleration.

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  1. Mass does not affect earthquake force
  2. Heavier buildings shake less, so force drops
  3. Greater mass produces greater inertia force ✔

Why: The ground accelerates the foundation while the structure's mass resists that motion. For the same acceleration, more mass produces more inertia force that the lateral system must carry.

Huh, didn't know that: A structure's period, stiffness, damping, and ground-motion frequency also affect its seismic response.

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References

Answer: Greater mass produces greater inertia force. The ground accelerates the foundation while the structure's mass resists that motion. For the same acceleration, more mass produces more inertia force that the lateral system must carry.

  1. Virginia Tech: Earthquake Loads www.setareh.arch.vt.edu/safas/007_fdmtl_05_types_of_loads_4.html
    These movements turn into earthquake loads when the ground acceleration (change of speed with time) is multiplied by the mass of the structure (F=ma).
    Checked 2026-10-10.

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