Shear wave velocity is an important parameter for evaluating the dynamic behavior of soil.In seismic design codes

the equivalent shear wave velocity is used as the key indicator to classify sites.However

the different calculation depths were chosen in different seismic codes.The correlation of equivalent shear wave velocities v

s

20

and v

s

30

corresponding to the depths of 20 m and 30 mare statistically analyzed on the basis of the measured data of shear-wave velocity from 446 boreholes in Suzhou study region.According to the site category standards in the seismic codes of GB50011—2010

N

EHRP and Eurocode 8

the spatial distribution characteristics of site categories in Suzhou region are compared.The results exhibit a significant linear correlation between vs

20 and vs

30

and the corresponding determination coefficient R

2

is 0.888.There are significant difference in spatial distributions of site categories presented by the codes of GB50011—2010

NEHRP and Eurocode 8.Furthermore

the equivalent shear wave velocities corresponding to the different codes vary greatly.According to the seismic code of GB50011-2010

theⅡcategory site is distributed among the local part in the western area of Suzhou region

theⅢcategory site is spread over the entire Suzhou region

and the Ⅳ category site is scattered in Suzhou region.As a comparison

the DUScategory site given by NEHRP code and the CEUcategory given by Eurocode 8 are distributed throughout the whole area.While the EUScategory site for NEHRP code and DEUcategory site for Eurocode 8 are distributed mainly over a long and narrow zone with an angle of 23°to the east-west direction.