Investigation on the dynamic responses of a truss spar platform for different mooring line groups

Abstract

The dynamic responses of any floating platform are dependent on the mass, stiffness and damping characteristics of the body as well as mooring system. Therefore, it is very essential to study the effect of individual contributions to the system that can finally help to economise their cost. This paper focuses on the effect of mooring stiffness on the responses of a truss spar platform, obtained by different grouping of lines. The study is part of our present researches on mooring systems which include the effect of line pretension, diameter and azimuth angles. The platform is modelled as a rigid body with three degrees-of-freedom and its motions are analyzed in time-domain using the implicit Newmark Beta technique. The mooring lines restoring force-excursion relationship is evaluated using a quasi-static approach. It is observed that the mooring system with lines arranged in less number of groups exhibits better performance in terms of the restoring forces as well as mean position of platform. However, the dynamic motions of platform remain unaffected for different line groups.

Effects of Damaged Fiber Ropes on the Performance of a Hybrid Taut-Wire Mooring System

“…In the fatigue analysis example of the API-recommended practice 2SK [34], the wind, wave, and current are assumed colinear. In addition, Ahmed et al [25,35] investigated the response of a truss spar under the unidirectional waves, current, and wind loads based on the observation that waves are accompanied by the current and the wind in practical situations.…”