Evaluation of the influence of frequency characteristics of input earthquake on seismic coefficient for gravity quay wall via dynamic centrifuge tests

Abstract

The pseudo-static approach has been conventionally applied for the design of gravity type quay walls. In this method, the seismic coefficient (k(h)), 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 k(h) considering frequency characteristics of input earthquake is critical for representing the real dynamic behavior. However, the definitions of k(h), which is used for simplified analysis in Korea, focus only on convenience, and the frequency characteristics of input earthquake are not reflected in the k(h) definitions. This paper evaluates the influences of the frequency characteristics of input earthquake on k(h) by initially reviewing the k(h) definitions in the existing codes of Japan for port structures and then by performing two 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 k(h) values are estimated differently 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 larger when long-period-dominant earthquake is applied.