Buildings and structures of critical infrastructure facilities: numerical modelling and analysis of floor response spectra

The paper presents a methodology and an example of determining the floor response spectrum of nuclear power plant building structures under earthquake loads. When critical energy infrastructure facilities are considered, the issues of regulation and scientific support for seismic safety are quite complex. For this class of structures, a comprehensive approach to the study of the system (soil-foundation—structure) is required. The type of foundation and its connection with the base play an important role. Existing regulations do not always take into account the specific features of the foundation, and the seismic resistance of the overground structure depends on the behavior of the foundation. For analyses of critical infrastructure objects, it is critical to take into account the soil properties and evaluate the seismicity of the territory. The paper presents peculiar features for dynamic analysis of energy infrastructure facilities and the main stages for analysis of floor response spectra. The paper demonstrates examples of design models for buildings and structures of critical infrastructure, namely, structural solutions for generating a model of a reactor. A mathematical model for dynamic analysis is presented. It takes into account both material damping and soil-foundation interaction [5]. The analyses apply the direct method of integrating the equations of motion, including the mathematical equations from which the min value of the damping coefficient is determined [6]. As a method for modeling the interaction between the base and the structure, the method of equivalent dynamic characteristics is adopted, according to which four independent stages are proposed for determining the design seismic impact; determining the coefficients of mass proportionality α and stiffness β; solving the problem of forced vibrations obtained from linear non-conservative oscillators, followed by obtaining floor response spectra.