Investigation of the condition and the behavior of a modular floating structure by harnessing monitoring data

In this paper, the condition and the behavior of an installed and operating Modular Floating Structure (MFS) is investigated and assessed by harnessing field monitoring data and using collectively multiple Correlation Coefficients (CCs) between measured quantities. The examined MFS consists of five pairs of interconnected floating concrete modules and it functions as a floating breakwater. The field monitoring data are acquired through a sensor network deployed on one pair of modules (connected through two groups of connectors) of the MFS. A methodological data processing framework for data organization, manipulation and post-processing is developed and presented. This framework enables the quantification of the structure's condition at different time periods through the calculation of CCs: (a) between the incident wave height and the tensions of the mooring lines and (b) between the tensions of the mooring lines, considering various wave directions. Recorded data at three characteristic time periods during the structure's lifetime are used, namely: (i) before any failure (structure's initial condition), (ii) after the failure of the first connectors' group and (iii) after the failure of the second connectors' group. The data processing framework developed in the present paper is applied to the above recorded data in order to calculate CCs and, therefore, quantify the structure's condition, at the three aforementioned time periods. The quantification of the structure's initial condition resulted to conclusions that were consistent from a physical point of view with the most recently documented, available in-situ mapping of the mooring lines' configuration in the horizontal plane. By considering the structure's initial condition as a reference base for comparison, the effect of the connectors' failure on the CCs, used to quantify this condition, was also investigated and efficiently assessed. Specifically, the significant changes observed in the variation patterns of all examined CCs, when compared with their respective patterns corresponding to the structure's initial condition, demonstrated and confirmed the existence of significant reformation of the examined structural system resulting from the connectors' failure. In this way, the effectiveness of the joint utilization of CCs to assess the structure's condition was proved.