Abstract
Recently earthquake ground motions with high frequency components have been observed on a regular basis. It is well known that the "effective input motion" is reduced in the high frequency range due to the effect of Kinematic interaction of the soil-pile system. Dynamic soil-pile interaction analyses, therefore, were conducted by varying the conditions of both the ground and piles, and the influence of input loss from the pile foundation was investigated. The result revealed that the input loss was negligibly small in case of ground motion whose amplitude was predominantly in the 1-2 Hz range, such as the Hyogoken Nanbu earthquake. On the other hand, the input loss was quite large in the case of high frequency seismic motion such as that observed in the Tohoku earthquake. A simplified expression of input loss, which could be used in practice for seismic design and is based on the Winkler-type spring model, was proposed.
