A vertical ship lift under earthquake excitation may suffer from a whipping effect due to the sudden change of building lateral stiffness at the top of the ship lift towers.This paper proposes a roof magnetorheological(MR)intelligent isolation system to prevent the seismic whipping effect on machinery structures.Theoretically,the dynamic models of MR damper and the mechanical model of ship lift was established,the inverse neural network controlling algorithm was proposed and the fundamental semi-active control equation for the Three-Gorges ship lift where the MR intelligent isolation system was installed was deduced.Experimentally,the experimental model of the ship lift was given,the vibrating table experiment of the MR intelligent isolation system controlling the whipping effect was carried out and the results of the inverse neural network control strategy and passive isolation strategy were compared.In practical aspect,the large-scale MR damper(500 kN)and a sliding support with limited stiffness were designed and fabricated.It was proven that the MR intelligent isolation system with proper control strategy can greatly reduce the seismic whipping effect on the top workshop of the ship lift and be simple and effective enough to be applied to real engineering structures.
