A theoretical study on the train-induced vibrations of a semi-active magneto-rheological steel-spring floating slab track

•A vertical rail vehicle-MR steel-spring FST coupled dynamic model is first established.•MR dampers used to support the traditional FST have no impact on vehicle security.•MR dampers under FST have conspicuous vibration-reduction effect at the basic frequency.•A semi-active control strategy of MR dampers under FST is necessary to suppress the negative effect.•Maximum MR damping force and displacement threshold are two key parameters in semi-active MR. In order to further improve the vibration-reduction effect of a steel-spring floating slab track (FST), especially at the inherent frequency of a steel-spring FST, semi-active magneto-rheological (MR) dampers were applied to support a floating slab in a traditional steel-spring FST. Based on the experimental study and the proposed theoretical model of the MR dampers with a simple semi-active control method, a vertical vehicle-magneto-rheological steel-spring FST coupled dynamic model was established. The proposed dynamic model was used for a safety analysis and a vibration-reduction evaluation to theoretically validate the feasibility of semi-active magneto-rheological steel-spring FST. It was concluded that the introduction of semi-active MR dampers to support a floating slab in a traditional steel-spring FST has no impact on the security of subway vehicles running on FST. MR dampers with a semi-active control strategy can effectively not only improve the vibration-reduction effect at the basic frequency of a steel-spring FST, but also they can also suppress the vibration-amplification negative effect under a floating slab above the basic frequency of a steel-spring FST. There are the two key parameters of the maximum MR damping force and the displacement threshold in a semi-active magneto-rheological steel-spring FST. The larger MR damping force can deteriorate the negative vibration-suppression effect under a floating slab above the inherent frequency of the FST, while the higher displacement threshold can decrease the vibration-attenuation velocity of the FST supporting force.