Wavelet-based Analysis Of Seismic Input Energy And Input Energy Analysis Of Wenchuan Earthquake

Effect of earthquakes on building structures is a process, that is, energy transfer, conversion, and absorption (dissipation). When the energy dissipation capacity of the structure is greater than the seismic energy input to the structure (input energy), the structure is not damaged, otherwise the structure would be damaged by the earthquake. Because the seismic analysis and design method based on energy has the definite concept and the simple form, contains the effects of many design factors (especially the ground motion duration) and has obvious advantage, and it is considered the future direction of the development of seismic design.Therefore, the study of seismic input energy has been one of the core of the energy analysis and even one of the core of seismic research. Previous research of ground motion energy is limited in the time domain,and wavelet theory provides the basis for further study of ground motion energy in the time-frequency domain for us. Using the method of wavelet decomposition, according to current research status of seismic input energy,and based on existing research results,the thesis deals with the earthquake input energy of single degree of freedom structural system in time history of energy and energy spectrum.The article taken the wavelet simulation analytical expressions of ground motion into the energy balance equation, get the expression of wavelet decomposition of input energy in the frequency domain, realize the seismic input energy to the wavelet decomposition. So the got total input energy of ground motion can be expressed as the superposition of different frequency bands of input energy. For each seismic wave,the relationship can be established between the total input energy and frequency ,and their behavior can be observed and analyzed from a new angle. The method is utilized to analyze the acceleration record of the M8.0 Wenchuan earthquake.The article selected six seismic station records as research subjects,they are the records of Wolong station, the Maoxian Nanxin station, Chencang station, Longxian station,Xi an station, and Caotan station. Using the wavelet decompose their input energy,and obtain the energy spectrum, to research the different records' nature. By decomposition of the input energy,we can see clearly the role of component which contains predominant period in total input energy,and the role of component is different for different seismic waves. For the input energy of any natural period structural system, the impact of the different frequency components can be obtained clearly.By research the peak of each component energy spectrum, measuring the proportion of each component input energy in the total input energy.And another aspect analysis can be obtained the spectral characteristics of seismic wave, the structure of the energy spectrum peak natural period same with the seismic waves' predominant period. So energy spectrum can also be used as a way to estimate the predominant period, at the same time, it can reflect the seismic response of different structural systems.