Earthquake engineering: just F = ma?

How does a familiar equation explain the complex movement of a building during an earthquake?

I made this short video to revisit the mechanics—from inertia and Newton’s second law to the equations of motion used in seismic analysis.

The key: F is the net force. Introducing D’Alembert’s equivalent inertia force, −ma, lets us express motion as a force balance. Apply that balance to each floor, account for the forces between floors, and the building’s equation takes shape.

The video also compares how changing mass, damping and stiffness affects its response to the same ground motion.

A personal learning exercise, shared with anyone curious about how structures respond to earthquakes.

#StructuralEngineering #EarthquakeEngineering #SeismicDesign