Study On Regional Probabilistic Hazard Based On Ground Motion Of Performance

Determining design ground motion parameters of engineering structures based on performance has gradually become the mainstream direction of seismic design,and the zoning of ground motion parameters for different performance states of structures will also be a new topic to be explored in the future seismic zoning.The performance-based probabilistic seismic risk analysis method can evaluate the expected performance of structures in a certain number of years in the future and provide a basis for the next generation seismic zoning.This paper conducts exploratory research in the following aspects:(1)Cascade earthquake catalogue selection and seismicity analysis based on DBSCAN clusteringThe characterization of seismicity model of earthquake time,space and intensity is studied.The temporal,spatial,magnitude and depth distribution characteristics of the Tan-Lu seismic zone and the South Yellow Sea seismic zone are described.This paper proposes a method to pick up the starting point of the time axis of the complete earthquake catalog based on DBSCAN clustering algorithm.According to the study of the earthquake interval of different magnitude ranges,the earthquake catalog of each cascade magnitude domain is generated,and the G-R seismicity parameters are fitted.The rationality of the method is verified by comparing with the fifth generation zoning map.(2)Probabilistic seismic risk analysis considering four levels of seismic actionThe differences of potential source division,seismicity parameter allocation,ground motion attenuation law and hazard calculation method between Chinese CPSHA method and PSHA method are described,and the reasons are analyzed.Based on CPSHA-Tool,the grid discrete field points of Qingdao were generated,and the potential source and its activity parameters within the 150 km influence field range superimposed by all the discrete field points were determined.Probabilistic seismic risk analysis considering uncertainty was carried out based on the ground motion attenuation model of the fifth generation zonal map.The spatial distribution maps of bedrock peak acceleration and response spectrum under four levels of seismic action(probability)in Qingdao,including multi-event,design,rare event and extremely rare event are given.The potential source contribution rate of the most dangerous region is decoupled.(3)Study on performance spectrumTaking RC frame as an example,the indirect mapping relationship between performance target and single degree of freedom period is given,and the coupling correlation between performance objective and period and standard height is studied.The concept of performance ground motion is described,and the dynamic boundary adjustment is carried out on the basis of dichotomous method.The calculation method of performance ground motion is proposed based on the approximation of the displacement function of the structural target.The calculation program is programmed with Python and optimized in the seismic wave truncation and the selection of time history analysis algorithm.A total of 1570 seismic waves of strong earthquakes at home and abroad are selected and grouped according to their characteristic periods.The elastic-plastic performance spectra within 0.5～2.0s were calculated under different site groups and different performance levels(performance targets).(4)Study on the probabilistic hazard of performance stateThe conversion method from elastic-plastic performance ground motion to elastic performance ground motion is studied.The effects of site grouping and standard height on the elastic-plastic state spectrum and elastic state spectrum were analyzed.Based on the results of seismic hazard and RBF radial basis function interpolation with complete interpolation,the multi-dimensional implicit relationships of regional longitude and latitude,period,performance ground motion and exceedance probability are established.The exceedance probability spatial distribution maps of different performance levels within 0.5～2.0s for A,B and C group of sites(site class Ⅰ)in Qingdao are given.(5)CPSHA-Tool for performance ground motion hazard analysis and visualizationBased on the combination of Python scripts and Web UI form,the field site generated,analysis of potential earthquake source,earthquake catalogue pretreatment,seismicity statistics and distribution,the ground motion attenuation visualization,computation of seismic hazard,seismic hazard visualization,calculation of performance ground motion,visualization of performance probabilistic hazard,a total of nine modules,are programed called CPSHA-Tool to assist the exploratory research in this paper.The main feature of CPSHA-tool is to vectorize the elements in the PSHA process,which makes spatial data processing and visualization more friendly and efficient.Aiming at the problem of calculating the intersection area between potential source and ground motion attenuation ellipse in CPSHA90 equivalent algorithm,a method based on vector Boolean operation is proposed,and its rationality is verified by comparison.