Performance Category 3 and 4 Structures, Systems, and Components - Continued

DOE-STD-1020-2002

which use F > 1, the maximum spectral acceleration should be used for

fundamental periods lower than the period at which the maximum spectral

amplification occurs (See Figure 2-4). For higher modes, the actual spectral

accelerations should be used.

Calculate the inelastic seismic demand element forces, DSI, as

DSI = SF

(2-1)

where:

= Inelastic energy absorption factor from Table 2-3 for the

appropriate structural system and elements having

adequate ductile detailing

= Scale factor related to Performance Category

= 1.25 for PC-4

= 0.9 for PC-3

Variable scale factors, based on the slope of site-specific hazard curves are

discussed in Appendix C, to result in improved achievement of performance

goals. Site specific scale factors for low seismicity sites should be quantified

to ensure that use of

S.F = 0.9 is adequately conservative. SF is applied for evaluation of

structures, systems, and components. At this time, F values are not

provided for systems and components. It is recognized that many systems

and components exhibit ductile behavior for which F values greater than

unity would be appropriate (see Section C.4.4.2). Low F values in Table

2-3 are intentionally specified to avoid brittle failure modes.

Evaluate the total inelastic-factored demand DTI as the sum of DSI and DNS

(the best-estimate of all non-seismic demands expected to occur concurrently

with the DBE).

DTI = DNS + DSI

(2-2)

Evaluate capacities of elements, CC, from code ultimate or yield values

Reinforced Concrete

Use IBC 2000, ACI 318 & ACI-349

Steel

Use IBC 2000 and AISC

- LRFD provisions, or

2-12