General Approach for Seismic Design and Evaluation

DOE-STD-1020-2002

The resulting seismic induced inertial forces be appropriately distributed

and a load path evaluation (see Section C.4.2) for structural adequacy be

performed.

A "dynamic analysis approach" does not imply that complex dynamic models must be

used in the evaluation. Often equivalent static analysis models are sufficient if the above listed

three factors are incorporated. However, use of such simplified models for structures in

Performance Category 3 or higher must be justified and approved by DOE. This dynamic

analysis approach should comply with the seismic response analysis provisions of ASCE 4 (Ref.

2-3) except where specific exceptions are noted.

The maximum ground acceleration and ground response spectra are used in the

appropriate terms of the IBC code equation for base shear. The maximum ground acceleration is

also used in the IBC code equation for seismic forces on equipment and non-structural

components. Use of modern site-specific earthquake ground motion data and the IBC 2000

requirements based on NEHRP provisions (Reference 2-6) maps are considered to be preferable

to the general seismic zonation maps from the previous codes and should be applied according to

the guidance provided in DOE-STD-1023 (Ref. 2-22). For structures, the IBC code provisions

require a static or dynamic analysis approach in which loadings are scaled to the base shear

equation value. In the base shear equation, inelastic energy absorption capacity of structures is

accounted for by the parameter, R. Elastically computed seismic response is reduced by R values

ranging from 1 to 8 as a means of accounting for inelastic energy absorption capability in the

IBC code provisions and by these criteria for Performance Category 2 and lower SSCs. This

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

code allowable response limits (or code ultimate limits combined with code specified load

factors). For concrete structures, the design detailing provisions from the IBC 2000 (for PC 1&

2) and ACI-349 (for PC-3 & 4) which provide ductility, toughness, and redundancy, are also

required such that SSCs can fully achieve potential inelastic energy absorption capability. For

structures constructed of other materials follow the relevant codes and standards specified in

Chapter 1. Normally, relative seismic anchor motion (SAM) is not considered explicitly by

model building code seismic provisions. However, SAM should be considered for PC-3 and

PC-4 SSCs.

Executive Order 12699 (Ref. 1-7) establishes the minimum seismic requirements for new

Federal buildings. NEHRP updates the provisions required to meet these requirements every 3

years. The Interagency Committee on Seismic Safety in Construction (ICSSC) compares model

building codes with the NEHRP provisions. Designers must consider the NEHRP provisions

and ICSSC comparisons to ensure the use of the proper model building code in their design and

evaluation. Currently the IBC 2000 and ASCE 7-98 meet the requirements of the NEHRP

provisions. While using the IBC 2000 or successor documents, designers must consider the

Seismic Use Group and Seismic Design Category.

The seismic provisions in the IBC 2000 have been specified for PC-1 and PC-2 because

it is the only current model code meeting NEHRP provisions. The Interagency Committee on

Seismic Safety in Construction has concluded that the following seismic provisions are

equivalent for a given DBE the and latest NEHRP provisions:

2-5