Empirical correlations of acceleration response spectra with other four categories of intensity measures for offshore ground motions

The empirical correlation equation is developed to predict the correlation between two intensity measures (IMs). Previous studies on empirical correlation equations have primarily relied on onshore ground motion, with limited consideration of offshore ground motion. The equation is not only applicable for selecting ground motion records based on the Generalized Conditional Intensity Measure (GCIM), but also for vector-based IMs probabilistic seismic hazard analysis. This paper is based on K-NET strong ground motions, including 892 offshore and 4033 onshore ground motions. Firstly, the Ground Motion Models (GMMs) for 0.1-10.0 s acceleration response spectra (Sa) and other four categories of IMs (amplitude, duration, frequency-content and accumulative effect) were established. Furthermore, empirical correlations between Sa and other IMs were analyzed based on GMMs and Fisher-z transformation. After conducting thorough research, we established the empirical correlation equations between Sa and other IMs of offshore ground motions, revealing significant differences in the empirical correlation equations based on offshore and onshore ground motions. Therefore, when applying the empirical correlation to the ground motion selection based on GCIM in ocean engineering, it is necessary to establish the empirical correlation equation using offshore ground motions rather than directly applying the empirical correlation equation based on onshore ground motions.