Document: NUREG-0800
Document ID: 072325a8-02ea-4d59-bb3f-06592c340804
Document Type: srp
Title: The Aluminum Association, Specification for Aluminum Structures
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070327.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.4
CFR Part: 
CFR Title: 

Content:
recorded dynamic earth pressures were substantially smaller than those given by the elastic solutions (Chang et al. 1990). On the basis of a detailed study of the Lotung site data, Chang et al. (1990) have concluded that the dynamic earth pressures acting on an embedded symmetrical structure are related primarily to soil-structure interaction (SSI) and that this phenomenon is different from that of a yielding retaining wall being acted upon by an active earth pressure. Thus, the concept of limiting equilibrium used in the M-O method is not strictly applicable to the dynamic earth pressures on embedded structures. Soydemir (1991) has also recommended caution in using the M-O method indiscriminately. He points out that the M-O method is being used without checking whether the retaining structures yield or not, and whether the conditions assumed in the M-O analysis are satisfied. Soydemir states that, even though the M-O equation for active earth pressure conditions is quite appropriate for yielding walls, it may underestimate the dynamic lateral pressures acting on rigid, nonyielding earth retaining walls or structures. Section 4.5 of Bechtel Design Guide C-2.44 (1980) states that the M-O method is used to evaluate the seismically induced lateral soil pressures in the earthquake-resistant design of both the retaining walls and the embedded portions of exterior walls of nuclear power plant structures. The Design Guide further states that, when the wall does not experience sliding or rotation, the elastic solution (EERL 73-05) becomes more appropriate. In such cases, in addition to the "at rest" static pressures, all the resulting dynamic forces are to be increased by a factor of 2 for consideration of such nonyielding conditions (e.g., the embedded walls of massive structures.) The report states that the value of 2 is based on the findings of Wood (EERL 73-05) and also on the fact that "at rest" pressures are about twice the active pressures. Since the factor 2 is for