Study On Calibrating Methods Of Seismic Site-specific Response Spectrum

Response spectrum is a method to clarify the spectrum characteristics of ground motion, and it is the foundation of seismic input determination in engineering seismic design. The site-specific response spectrum, which is one of the results for engineering site seismic safety evaluation, is often used as a basis of earthquake fortification. The scientific and rationality of the calibration methods will directly affect the results of engineering site seismic safety evaluation. In the past 80 years, people have been exploring the calibrating methods of site-specific response spectrum. However, due to the complexity of it, this problem is still one of the hot issues in the seismic research of geological engineering. Further research in this field is of great significance to promote the development of the theory of response spectrum and the seismic design of engineering. The main researches in this dissertation are listed as follows:(1)The principle and calibration process of Newmark three-parameter, double-parameter method and the least square piece-wise fitting calibration method are analyzed in detail. According to 8 records of Wen Chuan earthquake, the differences of design response spectrum and characteristic parameters, which result from these three different calibration methods, are compared. The advantages, disadvantages as well as applicability of the typical methods are reviewed. Then the existing problems and the improvement direction of the response spectrum calibration are presented.(2)In this paper, the principle, characteristics and applications of the simulated annealing algorithm is summarized. And the simulated annealing algorithm has been first applied to the response spectrum calibration. At last, the feasibility and rationality of this new method is verified by calibrating the design spectrum, whose characteristic parameters are given.(3)Simulated annealing algorithm and the least square piece-wise fitting calibration methods are respectively applied to two engineering projects. The site-specific response spectrum of 50 years and 100 years with different beyond probability are calibrated. The results show that the calibration parameters are relatively the best combination, which closer reflect the spectrum characteristics of ground motion. And the new method is simple and applicable.