Far-field strong earthquake effect in Tianjin coastal soft site

Using data from boreholes and related shear wave observations， and test results in Binhai sites，we found lots of correlative seismic analysis soil models. Selecting the far-filed ground motion record P0841 of 1992 Landers MW7.3 earthquake in California as basement input，we applied the equivalent linearization method，which is wildly used in engineering to analyze the far-filed strong earthquake effect，to find some qualitative and instructive understanding on soil seismic response. The results show that the amplification effect of seismic peak ground acceleration (PGA) in Binhai soft site is significant，but there are some differences in different class site，e.g.，the effect on Ⅳ class site reveals an obvious decrease. Moreover，the calculated response spectra ratio between basement and ground shows that the amplification effect of different frequency component of basement input is so different at Binhai soft site that short period motion even exhibits decaying. There is，however，a considerable amplification when the input seismic wave has principal period component coincide with the predominant period of the Binhai soft site. That would be a great risk for high-and super high-buildings constructed on soft site.