An one-dimensional soil layer model is employed to analyze the site effects of the designing ground motion in five kinds of non-hard rock sites

including firm rock site

soft rock site

upper bound soft-to-medium soil site

soft-to-medium soil site and soft soil site

for designing the foundation of AP1000 nuclear island (NI) structure. In this study

the shear wave velocity in the bedrock of the computational model is selected as 700

1 100 or 2 438 m/s. The input motion of the bedrock is taken as RG1.60

AP1000 and HAD101 spectra (with 5 damping ratios) matching with the synthetic acceleration time histories of ground motion provided in the relative technical documents and standards

respectively. Analytical results indicate that non-hard rock sites induce the significant changes of the peak ground acceleration and response spectrum of the ground motion

which is enhanced further by a softer site. The effects of non-hard rock sites

except the soft sites

amplify the peak ground acceleration and response spectrum. However

the effect of the soft site increases the peak ground acceleration and response spectrum in a lower frequency range

and it is opposite in a higher frequency range. The peak ground acceleration and response spectrum of the site ground motion are significantly influenced by the changes of the bedrock and its shear wave velocity of all non-hard rock sites. Moreover

the effect is proportional to the shear wave velocity of the bedrock

and the ground motion decreases obviously with the increase of shear wave velocity. The ground motion is unaffected by the shear wave velocity as the site changes from hard to soft. Considering the great effects of the site type and the bedrock selection on ground motion

it is thus necessary to analyze the applicability of the sites by using the AP1000 standard design in the nuclear power plant construction in China.