STUDY OF A METHOD OF CALCULATING NATURAL PERIOD OF OPEN-TYPE WHARVES WITH VERTICAL PILE CONSIDERING THE NONLINEARITY OF SOIL STIFFNESS ACCOMPANYING EARTHQUAKE GROUND MOTION

Abstract

 Natural period of open-type wharves with vertical pile is estimated from a spring constant of wharves calculated by frame analysis according to 2007 technical standards for port facility. But to this method it is pointed out that the calculation result deviates from the 2D-Seismic Response Analysis. In addition, this method is not affected by seismic motion, although natural period of wharves should be affected by strength of seismic motion because soil stiffness around piles decrease by seismic motion.
 In this study, we evaluate the natural period and decreasing rate of soil stiffness by Seismic Response Analysis, and organize the relationship between them. Thereby, we correct the current method to be consistent with the 2D-Seismic Response Analysis.