Performance Requirements (TBDY)

According to TBDY sections 2.2, 3.4 and 3.5, the objectives of the assessment or redesign consist of combinations of both a performance level and a seismic action, given an "acceptable probability of exceedance within the life cycle of the building" (design earthquake), as shown in the table below.

The target building performance levels refer to the state of damage in the structure defined through four limit states, namely Continuous Use (KK), Immediate Occupancy (HK), Life Safety (CG) and Collapse Prevention (BP).

Performance Level of Continuous Use (KK)
The Continuous Use after the earthquake (KK), according to TBDY, is a condition in which it is expected that damage is insignificant and structure does not need any repair measures. Structural elements are prevented from significant yielding and retaining their strength and stiffness properties. Non-structural components, such as partitions and infills should not be damaged.

Performance Level of Immediate Occupancy (HK)
The Immediate Occupancy (HK), according to TBDY, is a condition in which it is expected that no building operation is interrupted during and after the design earthquake, with the possible exception of minor importance functions. A few hairline cracks may occur in the structure.

Performance Level of Life Safety (CG)
The Life Safety (CG), according to TBDY, is a condition in which repairable damage to the structure is expected to occur during the design earthquake, without causing loss or serious injury of people and without substantial damage to personal property or materials that are stored in the building.

Performance Level of Collapse Prevention (BP)
The Collapse Prevention (BP), according to TBDY, is a condition in which extensive and serious or severe (non-repairable, in general) damage to the structure is expected during the design earthquake; however, the structure retains its ability to bear the prescribed vertical loads (during and for a period after the earthquake), but without other substantial safety factor against total or partial collapse.

The criteria for the selection of the Performance Objectives may be found in TBDY.