Research On Macro Seismic Damages And Ground Motion Parameters For Seismic Intensity Scale

The conception of the seismic intensity has been widely used inseismology and earthquake engineering. In China, the seismic intensity hasalways been used as the symbol of the strength of seismic activities forseismic zoning, and also as the basis for seismic fortification in practicalengineering. However, the seismic intensity is evaluated based on the macroseismic intensity scale, which is not an accurate scale. Recently, there are somany kinds of seismic intensity scales all over the world, which are differentfrom each other. Whether the measurements of the seismic intensity scalesare rational or not, has great influences on the earthquake prevention anddisaster mitigation as well as the safeguard of people's life and property.With the improvement of the scientific and technical levels, large numbersof ground motion data have been obtained in the worldwide. Utilizing theground motion parameters to evaluate the seismic intensity is a trend, andmany related researches have been carried out. However, the peakparameters and frequency spectra are generally used, and there aren't toomany researches on the relationship of seismic duration and seismic intensity.In view of the above conditions, in this paper, the studies on the macroseismic damage of the seismic intensity scale and the relationship of groundmotion parameters&seismic intensity are performed by using the sufficientearthquake records and detailed seismic damages. The main research contentand achievements are as follows:(1) Careful comparisons of seismic intensity scales home and abroadare done, including the distribution by building type, classification ofdamage extent, qualification of quantifier and macro description of buildingdamages, etc. Different from many former researches, the quantitativeanalysis on the seismic intensity scales are performed besides the macrocomparison and the average damage index of different buildings arecomputed. This digital comparison analysis is seldom seen. In the analysis,the seismic damage index of different intensity zones for various buildingsin different intensity scales are computed by two quantified methods, andthen compared and analyzed with the2008Chinese Seismic Intensity Scale(CSIS). Meanwhile, for the description of seismic damages and definition ofquantifier in the CSIS-2008, nine combined methods are utilized to quantizethe seismic damage index. In addition, the common property, existingproblems and reason of shortage of the seismic intensity scales are analyzed.It may be concluded that the differences and the shortages are mainly causedby that the macro description of the quantifier deviate from the actual seismic damage distribution.(2) A large number of seismic damage index data and research resultsobtained from previous earthquakes in China before2008Wenchuanearthquake, have been systematically collected and thoroughly analyzed.Based on these, the seismic damage index methods are used to analyze thestrong motion damages and quantify some seismic damage data to damageindex, and then to provide basic data for the determination of the extent ofthe average seismic damage index in the seismic intensity scales to make upthe lack of basic data. Through the thorough statistical analysis, the averageseismic damage indexes of different buildings for different intensities areobtained respectively, the differences of the seismic damage indexes forType A/B and C buildings are studied by the comparison with the2008CSIC,and the rationality of the regulations in the2008CSIC are verified.(3) Plenty of data for different types of buildings obtained from thetwo recent great earthquakes in China–Wenchuan Earthquake and YushuEarthquake, have been statistically analyzed. Firstly, the statistical analysisof seismic damage index are performed in12cities and towns in differentintensity zones of Wenchuan earthquake, and then compared with theseismic damage indexes in2008CSIC. Secondly, the seismic damageindexes of4413buildings of155towns and villages obtained in differentintensity zones of Wenchuan earthquake have been statistically analyzed andcompared with2008CSIC; and then339sampling investigated buildings inGyegu with an intensity of IX in the Yushu earthquake have been classified,and the seismic damage indexes of667buildings from36towns and villagesin Yushu earthquake have been statistically analyzed. Finally, theinvestigated results of Wenchuan and Yushu earthquakes have beencompared with the2008CSIC. By verifying the analysis results, it mayprovide the theoretical and practical basis for the future revision of theChinese Seismic Intensity Scale.(4) The strong motion data of many earthquakes home and abroad arecollected and organized, trying to establish the relationship between theground motion parameters and seismic intensities. Then, the regressionanalysis method on relationship of ground motion parameters and seismicintensity is proposed based on the effect of the seismic duration, and thesuitable relationship of duration and acceleration/velocity is established toseek their relationship with seismic intensity. The analysis results show thatthe relevance of ground motion parameters and seismic intensity would bestronger under the effect of seismic duration and would obtain more desiredresults.