構造物の地震応答問題における不確定変動量の取扱いに関する研究 : 第 4 報 不確定変動量からなる構造物の地震応答に関する数値的検討

Abstract

In Part I, theoretical treatment of earthquake response problems of a structure with non-deterministic variables was discussed, and in Part II and III, the stochastic properties of the non-deterministic variables concerning an earthquake response of a structure, such as the properties of the power spectral density of earthquake ground motions, the dynamic coefficient of subgrade reaction, the damping constant of a structure and so on, were statistically investigated using the observed or measured materials. In this paper, based on the theory of a stocahstic random response of a structure described in Part I and using the actual properties of the non-deterministic variables concerning an earthquake response of a structure prescribed in Part II and III, the numerical analyses of an earthquake response of a structure were carried out. The dynamic behavior of a 3-storied structure is introduced here as one of the numerical analyses. The power spectral density function of the earthquake ground motion used in this analysis has been obtained analyzing statistically the strong ground motion records at Muroran Harbor in Hokkaido in Part II. The coefficients of variations considered in the properties of the earthquake ground motions and the structure are shown in Table 2 and 3. Fig. 6 shows the stochastic distributions of the maximum responses. The coefficient of variations of the maximum displacements are about 0.3〜0.4 and the maximum displacements corresponding to 95% probability are about 1.8 times as much as the mean maximum displacements. This fact shows that the stochastic variation of earthquake responses of a structure is extremely important in case of designing a structure with safety against earthquake ground motions. If the stochastic properties of the non-deterministic variables relating to the problem of earthquake responses of structures can be obtained with sufficient accuracy, the response properties of the structure subjected to earthquake ground motions can be reasonably evaluated by the stochastic theory described in this thesis.