Building Design and Construction

• strength and flexibility of materials and design

  • wood houses are generally very safe

• size/proportions of the building

  • single-family homes generally have a low and squat geometry

• however, if you shake long enough, or is the building is on soft ground, even a wood-framed building will fail

  • this often means the building fell off its foundation

Liquefaction

• shaking causes unconsolidated soils and sediments to liquify

• ground loses cohesion and flows

• buildings fall down, can remain intact

• soil/sediment grains are touching in many places

• little space between grains so the ground is strong

• vibrations wiggle the grains, resulting in an increase in water pressure

• space between grains increases

  • grains can move easily so water can flow

• as soon as shaking stops, water pressure decreases

  • grains touch and soil becomes firm again