Intensity Characteristics of Ground Motion Vectors

Abstract

The Code for Seismic Design of Buildings stipulates that the ratio of combined values should be 1:0.85:0.65 when considering three-way seismic action. However, it is sometimes found that the difference between the horizontal records and the vertical records in the characteristics of ground motion and peak vibration is very different from those of the two. With the development of the seismic theory of the engineering structure, more complex structural systems have put forward more specific requirements for ground motion input. And the simple application of the three-dimensional seismic action to the combination of the 1:0.85:0.65 pairs of earthquakes is of limited applicability. In order to unify the ratio relationship of ground motion input components in multi-dimensional ground motion, the vector signal was constructed by the components of the ground motion vector. The components of the vector signal were orthogonal to each other in a complex space. So the correlation limit of bainite's theorem and Nuttall theorem was avoided when the orthogonal vector was constructed by Hilbert. At the same time, the problem of one dimension ground motion intensity characteristics to reflect the incomplete surface of the structure response was solved. Firstly, the ratio of the horizontal component and the vertical component to the three-dimensional envelope was calculated by the model fitting, and compared with the law of the traditional multi-dimensional ground motion ratio, and the reliability and practicability of the ratio rule calculated by the new method were clearly defined. Then the time-history characteristics of the ratio were obtained by the function fitting. The corresponding model parameters were obtained by the optimization algorithm and the attenuation law was studied. It is proved that the fitting model is correct and effective in the time-history analysis of ratio.