A Discussion on the Seismic Coefficient for Gravity Quay Wall Considering Frequency Characteristics of Input Earthquake

Abstract

Pseudo-static approach has been conventionally applied for the design of gravity type quay walls. In this method, seismic coefficient (kh), expressed in terms of acceleration due to gravity, is used to convert the real dynamic behavior to an equivalent pseudo-static inertial force for seismic analysis and design. Therefore, the calculation of an appropriate kh considering frequency characteristics of input earthquake is critical for representing the real dynamic behavior. However, the definitions of kh, which is used for simplified analysis in Korea, focuses only on convenience that is easy to use, and the frequency characteristics of input earthquake are not reflected in the kh definitions. This paper evaluates the influences of the frequency characteristics of input earthquake on kh by initially reviewing the kh definitions in the existing codes of Japan for port structures and then by performing a series of dynamic centrifuge tests on caisson gravity quay walls of different earthquake input motions (Ofunato, Hachinohe). A review of the existing codes and guidelines has shown that the kh values are differently estimated according to the frequency characteristics of input earthquake. On the other hand, based on the centrifuge tests, it was found that the permanent displacements of wall are more induced when long-period-dominant earthquake is applied.