Seismic Design Spectra Based On Statistical Probability

Seismic design spectra is the most fundamental basis for seismic design of engineering. Scientific and reasonable determination of the seismic design spectra to develop the engineering anti-seismic theory and guarantee the safety and economy of structural seismic design are of great significance.Earthquake happened in recent years and the cause of the nuclear power plant safety accident are taking people’s attention to seismic safety problems of nuclear power plant. The seismic design spectra of nuclear power plant as an important part of design earthquake has once again become the focal topic of the earthquake engineering fields. In the1960s, Newmark firstly gived the methods to set up the design spectra of nuclear power plant. He considered that statistics of a group of gauge response spectra in any period point approximately obey the lognormal distribution. Therefore, the average spectra value can be approximately equal to50%reliability design spectra value. Considering the particular requirements of nuclear power plant safety, it is recommended that the spectral value of the mean plus one standard deviation is used as design spectra value of nuclear power plant and its corresponding cumulative probability is84.1%. The determining method of the design spectra and understanding of probability have been in use today. The requirements for guaranteed probability of design spectra of nuclear power plant give people an important enlightenment:according to the important level of different engineering structures, we can adopt design spectra with different guaranteed probability to achieve or improve the reliability of structural seismic safety. Therefore, the determination of guarantee probability distribution model of spectra value for seismic design spectra and design spectra with certain guarantee probability are new problems that are worthy of in-depth discussion.The purpose of the study is establishing response spectra with different guaranteed probability based on the analysis to the optimal model of the spectral value probability distribution and providing a reference basis for giving design spectra that is suitable for different engineering structures with different guarantee probability for scientific and reasonable determination and expressing.This paper introduces several important probability distribution functions firstly and studies probability distribution model of the normalized spectra. We can calculate several response spectra with certain guarantee probability and research probability displacement response spectra based on the displacement design. Researching the influence on response spectra for ground motions recordings of different frequency contents. Mainly doing the following work:(1)Summarizing several kinds of typical probability distribution functions and the statistics related to expectation and variance corresponding probability guaranteed value. Introducing the test method of the spectra value probability distribution model and testing several spectra value probability distribution model of the normalized spectra.(2)Comparing the difference of average spectra with50%guaranteed spectra, and calculating several spectra curve with different assurance value and different damping ratio. Lastly, the curve fittings are carried on.(3)Comparing the mutual relevance of two kinds of classification methods according to the A/V and V/D ratio. Choosing normalized factor for displacement response spectra and researching displacement response spectra with A/V and V/D each three groups of classification.(4)Ground motions recordings are divided into several categories respectively according to their peak ground acceleration and the control periods of the response spectra. And different influences on several kinds of response spectra are researched.