Document: NUREG-0800
Document ID: 78905d69-1945-4638-99b9-2db68eb3da77
Document Type: srp
Title: SEISMIC SYSTEM ANALYSIS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070318.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.2
CFR Part: 
CFR Title: 

Content:
ffect of pore water on structural responses, including the effects of variability of ground-water level with time. 3.7.2-3 DRAFT Rev. 3 - April 1996 h. Effects of partial separation or loss of contact between the structure and the soil during the earthquake. The procedures by which strain-dependent soil properties (damping, shear modulus, pore pressure), layering, and variation of soil properties are incorporated in the analysis are reviewed. If applicable, the criteria for determining the location of the bottom boundary and side boundary of the analysis model are reviewed. The procedures used to account for effects of adjacent structures, if any, on structural response in the SSI analysis are reviewed. To perform a dynamic analysis for an SSI system, it may be necessary to have a well- defined excitation or forcing functions applied at the model boundaries to simulate the earthquake motion. It is therefore required in such cases to generate an excitation system acting at the boundaries such that the response motion of the soil media at the plant site in the free field is identical to the design ground motion. The procedures and theories for regeneration of such an excitation system are reviewed. Any other modeling methods used for SSI analysis are also reviewed as is any basis for not using an SSI analysis. 5. Development of Floor Response Spectra The procedures for developing floor response spectra are reviewed. There are several methods for generating in-structure response spectra. One method makes use of time history analysis by considering single or multiple (real or artificial) ground time histories which have spectra that, essentially, envelop the design response spectra. Another method involves a group of analysis techniques generally referred to as the direct solution methods for the generation of in-structure response spectra. These techniques do not involve time history analysis. The basis and justification for the use of either of the above methods are