The phase properties of ground acceleration records from Mw 5.5~6.5 earthquakes are analyzed. The interrelationships between phase properties and significant durations, as well as PGA, are clarified through both of theoretical and empirical approaches. The probabilistic characteristics of phase information is also discussed based on previous studies and it is shown that circular normal distribution is the most appropriate probability distribution for the phase angle and phase difference. Whereas those variates can be modeled by Gaussian random variables. From the survey results on the frequency dependency of the phase statistics, a simple model is introduced, which is possible to express the frequency dependency of phase information. It is also shown that the significant duration can be controlled by appropriately chosen standard deviation of phase difference for 4~8Hz frequency band and additional consideration of phase scattering in higher frequency band through a series of Monte Carlo simulations. The source of phase scattering effect is also pointed out and discussed.

강풍으로 인한 구조물의 파괴는 한계상태 이상의 풍하중으로 인한 파괴와 한계상태 보다 레벨은 낮지만 반복적인 풍하중에 의한 피로파괴로 나눌 수 있다. 한계상태설계 파괴에 대한 연구는 많이 이루어져 있으나, 강풍에 의한 피로파괴에 관한 연구는 드물다. 본 논문은 강풍에 의한 피로파괴 해석 시 사용할 수 있는 풍속의 계속시간에 관한 모델을 기상관측소로부터 획득한 자료를 사용하여 확률통계방법에 의하여 제시한 것이다. 강풍의 발생성인은 한국의 기상 특성에 따라 태풍, 전선풍, 계절풍으로 나누었고, 년최대풍 속자료에 대한 통계적인 처리는 극치Ⅰ형 누적분포함수를 사용하였다. 1회 강풍이 불었을 때 어떤 레벨에서 풍속의 계속시간은 풍속의 확률밀도함수와 최대풍속값에 의해 일반화된 누적신간의 곱으로 각 강풍의 발생성인에 따라 주어진다.

When conducting the seismic response analysis on a long elevated structure, if the transmitting boundary is set at both ends of the analysis region, there is a condition that the response becomes larger than in the case of the free boundary. In this research, we studied the influence of the effective duration time of earthquake motion on the maximum displacement amplitude of earthquake response and the response energy of earthquake when carrying out similar analysis using viscous boundary. As a result, it was confirmed that the correlation between the effective duration and the relationship between the viscous boundary and the maximum displacement amplitude ratio of the free boundary is low. On the other hand, for the relationship between the effective duration time and the response energy ratio between the viscous boundary and the free boundary, the variance was small and a certain correlation was confirmed.