Assessment of horizontal seismic coefficient for gravity quay walls by centrifuge tests

In the simplified analysis of seismic design of gravity quay walls based on the pseudo-static approach, selection of an appropriate horizontal seismic coefficient (k_h) is important for computing the equivalent pseudo-static inertial force. However, there is no unified standard for defining k_h. There are conflicts among the existing k_h definitions regarding whether it considers (a) the effect of wall height on maximum horizontal acceleration (MHA) used in the determination of k_h or (b) the application of correction factor for k_h according to seismic performance grade. This paper evaluates the relevance of these conflicts by initially reviewing the k_h definitions in the existing codes and guidelines for port structures and then by performing a series of dynamic centrifuge tests on caisson gravity quay walls of different wall heights (5, 10 and 15 m). A review of the existing codes and guidelines has shown that the correction factor for k_h should be specified according to the seismic performance grade for the economical design of quay walls. On the other hand, based on the centrifuge tests, it was found that the MHA used in k_h calculation and the correction factor for considering seismic performance grade should reflect the effect of wall height.