Document: NUREG-0800
Document ID: 8160c1fd-7cef-4c93-8e12-456019f2cfd2
Document Type: srp
Title: FOUNDATIONS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1319/ML13198A267.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.8.5
CFR Part: 
CFR Title: 

Content:
ance criteria for that load combination. For the pseudo-static and time history analysis methods, all three directional demand 3.8.5-10 Revision 4 – September 2013 forces should be considered to act simultaneously. Therefore, the resultant seismic forces (horizontal resultant force for sliding from the two horizontal forces and similarly the resultant overturning moment for overturning stability) should be considered. In the case of the sliding evaluation, if instead of using the resultant horizontal force with the vertical force, each pair of horizontal force and vertical force is evaluated separately, then the frictional resistance in the horizontal directions should be apportioned considering the existence of the two horizontal forces. If the stability evaluation is performed using a nonlinear time history analysis that includes foundation sliding and uplift, the analysis should consider the following criteria: i. The development of the set of time histories should follow the guidance described in SRP Section 3.7.1. This includes identification of the number of time histories needed to perform the nonlinear time history analyses and the development of each of the individual time histories. In this case, the guidance in SRP 3.7.1 II.B, Option 2, for multiple sets of time histories is applicable. ii. To demonstrate an adequate factor of safety, the seismic input time histories should be increased by a factor equal to the factor of safety for the applicable load combination (e.g., increase the seismic input time history amplitudes by a factor of 1.1 for load combination C). No, or minimal sliding, and no overturning should be demonstrated for each of the time history analyses. iii. The mathematical model should include the effects of sliding and uplift between the foundation and the soil media using appropriate finite elements that can simulate sliding once the frictional limit is reached and can simulate contact surfaces that can transmit compression but not