Accurate and reliable seismic input is a prerequisite for seismic response analysis of engineering structures. Based on the artificial boundary substructure method

the frequency-wavenumber domain (FK) semi-analytical method was integrated into the open-source finite element platform OpenSees. Combined with message passing interface (MPI) parallel computing technology

this integration enables equivalent input of P-waves

SV-waves

and SH-waves at arbitrary angles. After verifying the correctness of the developed seismic wave input methodology

a nuclear island structure located in a non-bedrock site was selected to analyze the effects of soil nonlinearity and geotechnical medium properties on its seismic response under oblique SV-wave incidence

considering soil-structure interaction (SSI). The research findings indicate: (1) Soil nonlinearity reduces the peak ground acceleration of the containment structure and significantly alters the internal force responses at the top and bottom of the pile foundation; (2) Variations in the dynamic properties of geotechnical media lead to changes in the stiffness of the soil-pile-nuclear island system

profoundly impacting the structural dynamic response. Specifically

sandy or silty soil layers with dynamic characteristics exhibit strong filtering effects on high-frequency seismic components

amplifying the bending moments in pile foundations adjacent to such layers. This study provides an effective tool for addressing external seismic input problems using the OpenSees platform.