Safety of Maglev Trains Moving on Bridges Subject to Foundation Settlements and Earthquakes

This paper investigates the safety of a series of maglev trains moving on multispan bridges undergoing foundation settlements and earthquakes. Rail irregularities, the proportional-integral (PI) controller with constant tuning gains, and maglev train-guideway-bridge interactions are considered in the three-dimensional (3D) nonlinear finite-element analysis. The numerical results indicate that the air gaps are slightly dependent on the train speed for the foundation settlements, but are almost independent of it for the seismic loads. When the initial ratio of lateral-to-vertical electromagnetic forces (Gy/Gz) is enlarged, the maglev train can sustain a larger earthquake. For the train with 1-cm air gaps and uniform maglev forces, the finite-element results indicate that the difference in the critical vertical foundation settlement between two piers can be extended to 3 cm, and the critical bridge lateral deflection can be extended to 2.2 cm under Gy/Gz=1. For seismic loads, the maximum lateral ground acceleration can be extended to 410cm/s2 for the air gaps equal to 10 cm under Gy/Gz=0.5. These conditions indicate that the electromagnetic suspension (EMS) system can overcome the problem of foundation settlement, and the electrodynamic suspension (EDS) system can overcome both foundation settlement and earthquake problems. (C) 2014 American Society of Civil Engineers.