A typical RC building is made up of horizontal members (beams and slabs) and vertical members (column and wall), and supported by foundation that rest on ground. The system comprising of RC columns and connecting beams is called RC frame, the frame participates in resisting the earthquake forces. Shaking due to earthquake develops the inertia forces in the building which are proportioned to the building mass. Earthquake-induced inertia forces preliminary develop at the floor level of these forces downwards through slab and beam to columns and walls and then to the foundation from where they are dispersed to the ground. Inertia forces accumulate downwards from the top of building. The columns and wall at the lower storey experience higher earthquake-induced forces and are therefore designed to be stronger than those in stores above.
When beams bend in the vertical direction during earthquakes, these thin slabs bend along with them. When beams moves with column in horizontal directions, the slab usually forces the beams to move together with column in horizontal direction, the slab usually forces the beams to move together with. This behavior is known as rigid diaphragm.
For building to remain safe during earthquake shaking; the columns (which receive forces from beams) should be stronger than beams and foundations (which receive forces from columns) should be stronger than columns. Connection between beam and columns, columns and foundation should not fail before the failure of beam.