Current Status

DOE-STD-1020-2002

Different structures, systems, or components may have different specified performance

goal probabilities, PF. It is required that for each structure, system, or component, either: (1) the

performance goal category; or (2) the hazard probability (PH) or the DBE together with the

appropriate RR factor will be specified in a design specification or implementation document that

invokes these criteria. As shown in Table C-3, the recommended hazard exceedance

probabilities and performance goal exceedance probabilities are different. These differences

indicate that conservatism must be introduced in the seismic behavior evaluation approach to

achieve the required risk reduction ratio, RR. In earthquake evaluation, there are many places

where conservatism can be introduced, including:

Maximum design/evaluation ground acceleration and velocity.

Response spectra amplification.

Damping.

Analysis methods.

Specification of material strengths.

Estimation of structural capacity.

Load or scale factors.

Importance factors/multipliers.

Limits on inelastic behavior.

10.

Soil-structure interaction (except for frequency shifting due to SSI).

11.

Effective peak ground motion.

12.

Effects of a large foundation or foundation embedment.

For the earthquake evaluation criteria in this standard, conservatism is intentionally

introduced and controlled by specifying (1) hazard exceedance probabilities, (2) load or scale

factors, (3) importance factors, (4) limits on inelastic behavior, and (5) conservatively specified

material strengths and structural capacities. Load factors have been retained for the evaluation

of PC-1 and PC-2 SSCs because the IBC approach (which includes these factors) is followed for

these categories. These factors are not used for Performance Category 3 and higher SSCs.

However, a seismic scale factor SF is used to provide the difference in risk reduction ratio RR

between PC-3 and PC-4. Material strengths and structural capacities specified for Performance

Category 3 and higher SSCs correspond to ultimate strength code-type provisions (i.e., ACI

318-99 for reinforced concrete, LRFD, or AISC Chapter N for steel). Material strengths and

structural capacities specified for PC-1 and PC-2 SSCs correspond to either ultimate strength or

allowable stress code-type provisions. It is recognized that such provisions introduce

conservatism. In addition, significant additional conservatism can be achieved if considerations

of effective peak ground motion, soil-structure interaction are introduced, and effects of large

foundation or foundation embedment are ignored.

C-7