Determination Of Design Earthquakes Based On The Dynamic Properties Of Engineering Structures

With the fast development of science and technology in China, lots of criticalengineering structures have been constructed all over the country. It's inevitable that some ofthem may be constructed in the regions where earthquakes frequently occur. Once thesecritical engineering structures are destroyed, they will bring serious secondary disasters andinestimable economic loss. Whereas the tremendous economic losses and deaths of people, aswell as the enormous effects on the harmonious and continuous development of society in thepast earthquakes home and abroad, both government and society should pay more attention toimproving the level of prediction and increasing the seismic safety of the critical structures.To decrease the level of unacceptable seismic risks, the practical and efficient approachis to determine design ground motion for these critical structures reasonably by seismichazard analysis. With the fast development of computer and the maturity of numericalcomputing technology, lots of vital or complicated engineering structures need using timehistory analysis to simulate the true earthquake dynamic processes. Accordingly, the selectionof design ground motion for critical engineering facilities should not limit to the experientialstatistics of ground motion parameters. However, it should be determined by special seismichazard analysis.(1) In this paper, the practical significance of seismic hazard analysis and two commonmethods including their advantages and disadvantages are introduced. Then the existingproblems and shortcomings in seismic hazard analysis are proposed.(2) The characteristics and principles of determination of design earthquakes, as well asthe practical significance are introduced. And then the related problems of determining designearthquakes are discussed by detail, including the selection of ground motion parameters, thedetermination of seismic regions and belts, the division of potential seismic sources, thedetermination of seismic activity parameters, the selection of attenuations of ground motion,the determination of magnitudes and epicentral distances of design earthquakes and theeffects of uncertain factors.(3) A method of determining design ground motion based on the dynamic properties ofengineering structures is proposed. Then its practicability and applicability are discussed bytwo examples. They illustrates that the design ground motion should be determined based on the characteristics of engineering structures whether the same building is constructed indifferent regions or different buildings are constructed in the same region.(4) The practical significance of compose ground motion is discussed. Then theprinciples and methods of composing ground motion are introduced briefly. At last,considering the practical seismic conditions of sites and the results of design earthquakes, thesamples of time histories of ground motion at different levels of probability of exceedanceboth in Dalian and in Donggang are determined and 12 groups of time histories of realearthquake ground motion are chosen from the ground motion data base of the west of USA.