Discussion On The Attenuation Relationship Based On The Strong Ground Motions In Western China

It is well known that seismic ground motion attenuation relations have always been playing an important role in the field of earthquake-related hazard analysis,seismic design and preparation of seismic zoning maps,etc.After decades of research and exploration,ground motion attenuation theory relations are maturing,the results of numerous,especially in recent years,the development of NGA is to study ground motion attenuation relations to a new milestone.At the same time,along with the strong motion data gradually enriched,the model being more perfect considering the hanging wall effect and direction effect and the peak acceleration,peak velocity,vertical ground motion,absolute cumulative rate,Arias intensity,spectral and so on,the ground motion attenuation relationship of different regions have been constantly achieving perfect opportunity.Therefore,it is also necessary to establish a more perfect and comprehensive China's new generation of ground motion attenuation relationship of CNGA,which can consider various factors.In order to reduce the large errors of analysis results due to the uneven distribution of data,this paper still selects the western region,where the strong motion data are relatively rich,as the research object.The main content of the paper are as follows:?1?First,from the data,models and regression methods angles,the history and achievements of domestic and foreign research on ground motion attenuation relationship are introduced.Taking into account the seismic data continuously enriched,especially in the west of China,there is an urgent need for further improvement of West China ground motion attenuation relationship.?2?By collecting,processing and calculating seismic data in western China of recent years,the information of independent variable for the seismic dynamic attenuation relation function,including magnitude,fault distance,Vs₃₀,fault type,focal mechanism and so on,are formed.At the same time,the information of dependent variable for the seismic dynamic attenuation relation function,including peak acceleration,peak velocity,cumulative absolute velocity,Arias intensity and response spectrum,are also formed.Among them,the improvement of the seismic data contains a total of 25 major earthquakes,as well as 27 aftershocks of Wenchuan and 7 aftershocks of the Lushan,a total of 3348 ground motion records,which greatly expand the number of before.?3?According to the data collated and distribution trends combined with previous research results,by the residual standard deviation judgment method,the basic model,the local model on behalf of the impact of the fault type,the local model on behalf of the impact of the site,the local model on behalf of the impact of the hanging wall effect,the local model on behalf of the directivity effect are gradually established,thus forming a complete improved ground motion attenuation relationship model.?4?On the basis of reliable data and the improved model,using the random effects approach,the peak ground acceleration,peak velocity,Arias intensity,cumulative absolute velocity and response spectrum are regressed respectively,giving the corresponding results,including horizontal and vertical in both directions.Thereafter,the regression results were compared.The first comparison is vertical to the horizontal component of the results which show that the ratio of high and low is not limited to 2/3,most likely more than one,and that we should consider.Subsequently the ratio is also viewed as a ground motion parameter and is again returned,giving the corresponding results.On the other hand,in both the horizontal and vertical ground motions,respectively,the respective distribution trend of all the parameters are compared by different models,the results show that the model of this paper is much better than other models,especially reflected in the overall residual standard deviation,which is less.