Dimension reduction method and system for fully non-stationary random seismic motion field

The invention discloses a dimensionality reduction method and system for a fully non-stationary random seismic motion field. The method comprises the steps that a white noise filtering model of seismic ground absolute acceleration is obtained according to an equation of motion of a surface soil layer; replacing the white noise process with the infinite bandwidth with the white noise process with the limited bandwidth, and obtaining a time domain model of the stationary seismic oscillation process based on the white noise filtering model; simulating a limited-bandwidth white noise vector process by adopting a POD method to obtain a component process POD expression of the limited-bandwidth white noise vector process; based on the time domain model of the stationary seismic oscillation process, introducing a dimensionality reduction idea of a random orthogonal function to obtain a time domain dimensionality reduction model of the stationary seismic oscillation component process; introducing a time-frequency modu