Influence Of Uncertainty Of Intensity Envelope Function’ Parameters On Soid Layers Seismic Response

Synthetic ground motion is an important part of Seismic hazard assessment that can provide the base ground motion import for soil layers seismic response analysis. The parameters can gained from statistics of strong ground motion, and it will be different for different researchers. The parameters can be different to a same target spectrum in different parameter determining methods. And it will affect the synthetic ground motion. The soil layers seismic response analysis will also be affected, and the result of design ground motion will be changed. So it is important for seismic hazard assessment to study the affection of changing parameters of intensity envelope function.In this paper, we adopt a three-stage model of intensity envelope function, combined with the actual engineering sites in recent years is widely used in seismic safety evaluation work of several farm vibration time history strength envelope function parameters formula, discusses the two main parameters in the model(on the cut-off time T1 and relatively stable strong ground motion duration Td) under different magnitude and epicentral distance scope. Study the effect of soil layers seismic response analysis by changing the parameter of intensity envelope function. The main contents are shown as follows:1. Show the importance of intensity envelope function in seismic hazard assessment. Systematically review the history of the intensity envelope function study, and summarize the latest research achievements of intensity envelope function.2. Use Yu’s China East Basement Peak Acceleration and Attenuation Law to simulate the target spectrum. Obtain the range of parameter by using four usual methods which can gain the parameter of intensity envelope function. Finally synthesize the ground motion which needed in this paper.3. Change T1 and T2-T1 in reasonable range for different magnitude and epicentral distance, and synthesis ground motion. Use half of the synthetic ground motion as basement ground motion import, discuss the soil layers seismic response of four typical soil models and gain the peak acceleration.4. Analysis the solid layers seismic calculation results in statistic methods and get the conclusions below:(1) The changing in Td affect more in horizon peak acceleration than that in T1,and the changing in Td also affect more in soil layers seismic response than T1 in ground horizon acceleration spectrum.(2) The changing in parameters of intensity envelope function affect the solid layers seismic response more in near-field ground than far-field ground.(3) Ⅰ site amplification factor affected by parameters of small, Ⅱ, Ⅲ, Ⅳ site amplification factor affected by parameters of degree is bigger.(4) The changing in parameters of intensity envelope function affect differently in different soil models,it will be more in site categoryⅡ, Ⅲ and Ⅳ.