A simple site amplification model originating from the NGA project for deep soft soil deposits in Suzhou, China

Site amplification models were developed as part of the Next Generation Attenuation (NGA) project to evaluate potential seismic risks in areas of North America. However, these models have low validity in seismic risk prediction in deep soft soil deposits (DSSDs) due to the lack of sufficient seismic recordings collected from DSSDs and site-specific dynamic parameters of local soils. Soil profiles from Suzhou City, China were used to validate the NGA nonlinear site amplification model (referred to as WSA08) and establish a simpler one based on 1-D site response results with high-frequency dominated (HFD) input motions. Fully nonlinear (NL) method which can capture the nonlinear behavior of soft soils was used to establish the simple functional form of nonlinear amplification model. Compared with WSA08, an accommodation coefficient A was added to adjust the ordinate of the Amps, while the linear amplification component was removed due to the epistemic uncertainty of linear amplification in DSSDs. The practicality of the simple model was validated using another three HFD input motions at different periods.