Shaking Table Test and Finite Element Analysis of Isolation Performance for Diesel Engine Building in a Nuclear Power Plant

Base isolation technology, as a mature seismic mitigation method, demonstrates potential for enhancing seismic margins in nuclear power plant structures. This study investigates the seismic performance of isolated and non-isolated models for a diesel generator building in a nuclear power plant through shaking table tests. A 1/8-scale structural model was designed and tested under operational safety ground motion (SL-1), ultimate safety ground motion (SL-2), and beyond design benchmark ground motion (BDBE) seismic excitations. A finite element model considering different tensile and compressive stiffnesses of isolation bearings was established to simulate structural dynamic responses under test conditions. The results demonstrate that the test model design is effective, with the maximum isolation rate was close to 50%. The maximum displacement of the isolation layer meets the collision prevention ditch limit. Numerical simulations showed good agreement with experimental results in acceleration time histories, displacement time histories and bearing hysteresis curves. Additionally, the seismic isolation structure has a certain overturning effect in the test. To further optimize the base isolation scheme, numerical analyses incorporating dampers into the isolation layer were conducted, which demonstrated improvements in mitigating the rocking effect of the superstructure.