Abstract
To enhance current seismic performance verification measures on crucial civil engineering structures in nuclear power plants, we examined the effects of vertical ground motions on seismic performance of reinforced concrete underground structures. For this purpose, computational works using nonlinear FEM analysis were performed for representative structures such as circulating water pipe supporting duct and water inlet pit. Emphasis was placed on the response nature of these structures subjected to simultaneous horizontal and vertical ground motions and the response fluctuation arising from peak value time lag of respective ground motion. Finally, the handling of vertical ground motion in terms of a seismic load in the seismic verification system was discussed.
