VALIDATION OF MODIFIED SUBSTRACTION METHOD FOR SEISMIC SSI ANALYSIS OF LARGE-SIZE EMBEDDED NUCLEAR ISLANDS
Dan M. Ghiocel1, Dongyi Yue2, Hiro Fuyama, Tomoyuki Kitani3 and Michael McKenna2
2 URS Energy and Construction, Princeton Office, New Jersey, USA
3 Mitsubishi Heavy Industries, Ltd. Kobe, Japan
The paper presents the selected results of the validation study for the application of the Modified Subtraction Method (MSM) to the seismic soil-structure interaction (SSI) analysis of the MHI US-APWR Reactor Building complex. The MSM method is based on the SASSI Flexible Volume substructuring approach in the complex frequency domain. The MSM is much faster than the reference Flexible Volume (FV) method that could be impractical due the large computational resources needed for large-size SSI models. However, the recent drafts of the ASCE 04-2013 Standard and USNRC SRP 3.7.2-2013 recommend that MSM is checked against the reference FV method before is applied to SSI production runs for seismic design-basis analyses of nuclear structures. The focus of this paper is on the MSM validation when applied to SSI analyses of large-size embedded NI complex SSI models. The comparisons of the SSI results of the MSM and FV methods obtained for the investigated case studies indicated that MSM is a highly accurate and efficient SSI analysis method. In addition, the paper introduces new methods, called Fast Flexible Volume (FFV) methods, that for particular excavation configurations could be more accurate than MSM, and still maintain a high numerical efficiency when compared with the reference FV method.