Vertical Seismic Effect on the Seismic Fragility of Large-Space Underground Structures

Table 1

Division of performance levels for large-space underground structures.

Performance levels	Damage states	Description of performance levels
Fully operational	No damage	Structure components do not suffer damage. Structures can be used normally.
Operational	Repairable	Strength and stiffness of structure maintain the same before and after the earthquake. Structures can be ensured its function with minor repair.
Life safety	Irreparable	Structure components experience serious damage and stiffness degeneration but are not collapsed.
Near collapse	Severe	Structure components are destroyed, and their strength and stiffness degenerate greatly. Structure nearly collapses.