Multivariate assessment of port operability and downtime based on the wave-induced response of moored ships at berths

Abstract

A methodology for a multi-process and multi-variable assessment of port operability/downtime in harbors, based on the historical characterization of the wave-induced response of moored ship systems at berths, in relation to both the historical outer- and in-port spectral wave climate, is presented in this paper. A joint numerical modeling and statistical approach is adopted with the objectives of exhaustive evaluation of port operability, uncertainty bounding and computational efficiency. First, the most accurate numerical configuration to predict the multivariate response of the moored ships is determined from an extensive catalog. This is done through a prototype-data-based performance assessment, where the complete time and spectral distributions of motion variables are used, instead of the classical time-averaged or spectrum-aggregated parameterizations. Secondly, an efficient assessment of port operability/downtime and safety is achieved based on a multivariate system response pattern-type approach related to representative wave climate conditions. This multi-process characterization allows to identify specific wave climate and mooring conditions triggering downtime or unsafe situations at berths. In addition, a tailor-made mooring plan can be suggested for each situation, also visualizing the operability and safety levels relative to each system response variable. Finally, a further characterization based on joint probability functions of motion amplitudes and periods over the berthing event?s duration is proposed, showing the time variability of motion variables, and suggesting advancing beyond the classical monoparametric definitions.