Model investigations for seismic responses of a scaled polar crane at a nuclear power station

Abstract

In order to investigate the seismic responses of a polar crane at a nuclear power station, a 1:16 scaled model (CL = 16) which uses the same material as the prototype, is designed. The similarity constants between the prototype and model are derived based on similarity criteria and different experimental aims. In order to ensure similarity in gravity and ignore similarity in stress, the similarity ratio of time between the prototype and model must be Ct = 161/2. To ensure similarity in stress and ignore the gravity field (self-weight), the similarity ratio of time must be Ct = 16. Similarities in gravity and stress cannot be ensured simultaneously. The correctness of derived similarity constants is validated by numerical methods. The experiment results show the eigen-frequency and damping ratio of the scaled model, investigate dynamic response characteristics of the model and magnify characteristics of acceleration and response spectrum at polar girder elevation, by comparing with input earthquake loads at shaking table. The different similarity ratios of time of experimental models can induce different dynamical responses of the polar crane, even if the acceleration similarity ratios for Ct = 4 and Ct = 16 are all equal to 1. Different similarity ratios of time of experimental models change the frequency characteristics of earthquake inputs on the shaking table.