Table C- 4 General Description of Earthquake Provisions

DOE-STD-1020-2002

in which combined element forces due to all concurrent loadings are reduced. The same F

values are specified for both Performance Categories of 3 and 4. In order to achieve different

risk reduction ratios, RR, appropriate for the different performance categories, the reduced

seismic response is multiplied by a seismic scale factor, SF. Different seismic scale factors SF

are specified for Performance Category 3 and 4. The resulting scaled inelastic seismic response

is combined with non-seismic concurrent loads and then compared to code ultimate response

limits. The design detailing provisions from the ACI 349, which provide ductility, toughness,

and redundancy, are also required such that SSCs can fully realize potential inelastic energy

absorption capability. Also, explicit consideration of relative seismic anchor motion (SAM)

effects is required for Performance Category 3 and higher.

For Performance Category 3 or higher, the dynamic analysis based deterministic seismic

acceptance criteria specified herein are independent of both the desired risk reduction ratio and

the performance category specified, other than for the seismic scale factor, SF. Thus, the

deterministic acceptance criteria herein may be used over a wide range of applications including

special situations where the desired seismic performance goal differs from those specified in

Tables C-1 and C-2.

Table C- 4 General Description of Earthquake Provisions

Performance Category 2 and Lower SSCs

Performance Category 3 and Higher SSCs

- Perform dynamic analysis considering the mass

Use IBC provisions

& stiffness distribution of the structure.

- Perform an elastic response spectrum analysis

but to permit limited inelastic behavior. Elastic

seismic response is reduced by the factor, F to

obtain inelastic seismic demand. Explicitly

account for relative displacement effects, where

applicable.

C.4.1

Dynamic Seismic Analysis

As mentioned previously, complex irregular structures cannot be evaluated by the

equivalent static force method because the simple formulas for distribution of seismic forces

throughout the structure would not be applicable. For such structures, more rigorous dynamic

analysis approaches are required. In addition, for very important or highly hazardous facilities,

such as for Performance Categories 3 and higher, seismic design or evaluation must be based on

a dynamic analysis approach. Dynamic analysis approaches lead to a greater understanding of

seismic structural behavior; these approaches should generally be utilized for more hazardous

facilities. Minimum requirements for dynamic analyses were presented in Chapter 2. It should

be noted that the requirement for dynamic analysis does not also require complex dynamic

models. For simple structures or components, very simple analyses can be performed as long as:

C-21