Seismic margin assessment of the real dynamic response of nuclear engineering structures based on the response envelope method

Abstract

The accuracy of response calculations for nuclear structures is directly related to the reliability of margin assessment results. The seismic response envelope (SRE) method, which is more effective than the traditional mode decomposition response spectrum method, has received increasing attention in studies on structural dynamic responses in nuclear engineering. It is able to consider the characteristics of multiple seismic responses occurring simultaneously, but applying it to the seismic margin assessment of structures beyond design-basis earthquakes becomes a challenge and some practical issues remain unaddressed. Focusing on the characteristics of the seismic response spectrum and regularization of the coordinate system, this study derived an SRE concentric circle equation in the regular coordinate system and defined the seismic safety margin level. A seismic margin assessment strategy for nuclear shear wall structures was developed based on the relationship between the bearing capacity surface controlled by the reinforcement ratio and the concentric circle of the SRE. A comparison between the SRE method and other seismic analysis methods for multiple seismic response calculations verified the effectiveness of the proposed method. Moreover, in particular, the emphasis was on the variation characteristics of the seismic safety margin level considering discrete points under the new and old strategies, and the solution accuracy and efficiency of the proposed strategy were discussed. Finally, the SRE method was used to evaluate the seismic margin of a real nuclear engineering structure, providing reliable data support for the solution strategy in practice.