Level

Resulted damage description

Operational (O)

Very simple light damage, no permanent displacement, structure returns to its own strength and stiffness after load removing.

Immediate occupancy (IO)

Light damage, no permanent displacement, structure returns to its own strength and stiffness after load removing, elevator can be restarted, fire protection operable

Life safety (LS)

Moderate damage, some permanent displacement, some residual stiffness and strength still in the structure stories, damage to partitions, building may need large repairing cost.

Collapse prevention (CP)

Severe damage, large displacement, little residual stiffness and strength, structure is close to collapse.