A 3D non-linear finite element approach is developed to study the free-field seismic ground response and the soil-structure interaction (SSI) phenomena at the Lotung site (Taiwan) during the earthquake event occurred on May 20 1986. The site was extensively instrumented with down-hole and surface ac- celerometers, these latter located also on a 1/4–scale nuclear power plant containment structure. An advanced constitutive model is adopt- ed for simulating the soil behaviour, while a linear visco-elastic be- haviour is assumed for the structural model. The free-field and SSI analyses are carried out applying both the NS and EW horizontal components of the acceleration time history as recorded at the depth of 47 m b.g.l. The predicted ground response re- sults are in fair agreement with the recorded motion at depth and at the surface. The dynamic response of structure is well captured for this specific seismic event, thus confirming the validity of the numerical approach
