Optimal design of nuclear power plants containment with tuned mass damper inerter device for earthquake loadings

In this paper a novel passive device defined as the tuned mass damper inerter (TMDI) is studied to control the response of a base-isolated nuclear power plant containment (BI-NPPC) structures under stochastic horizontal ground motions. A new method of connecting TMDI to the isolation foundation is proposed. Recently, the TMDI has been introduced as a generalization of the classical TMD to achieve enhanced performance. Consider the case of a base-isolated structure equipped with a TMDI device, which is served as a base-isolated nuclear power plant containment. A particular arrangement of mechanical gearings (inerter) attached to TMD is set, optimum parameters of this system are found based on a simplified two degree of freedom model that reflects the dynamic properties of both the isolation structure and the TMDI. A straightforward numerical approach is developed for the optimal design of this device considering a white noise ground excitation, and a simplified analytical solution for the optimal design of TMDI parameters are introduced and compared with the numerical results in terms of the optimum frequency ratio, the optimum damping ratio and enhanced performance. Within a probabilistic framework, the influence of soil conditions is investigated by modeling the seismic ground motion as a filtered Gaussian random process. Different filter parameters are considered that may be associated with firm, medium or soil conditions depending on the frequency content of the power spectral density function. Several natural recorded accelerograms are also selected to scrutinize the effectiveness of the TMDI isolated-base structure via time-domain analyses. Properties of the BIS are considered in respect of its damping and stiffness. It can be concluded that higher control performances are achieved when lower values of base isolation sub-system damping ratio are used, however, the control performances of the TMDI are basically not affected by small variation of the natural frequency of the isolated-base structure.