The dynamic response of a three-leg articulated tower

Articulated towers are a compliant type of platform particularly suited for deep water applications. In the design of articulated towers, it is very important that the motion characteristics include sufficient stability, less acceleration in the deck and the smallest possible loading on the articulated joint. The mass distribution along the tower also plays an important role in the motion characteristics of the tower. Multi-leg articulated towers with three or more towers (legs or shafts), which have been developed from the conventional single tower have reduced horizontal movements and have more deck area compared to the single-leg articulated towers. The experimental and analytical investigations on such towers are not available in the published literature. In this paper, both analytical treatment and an experimental program for a three-leg articulated tower model have been reported. The effect of mass distributions on the variations of the bending moment and the deck accelerations are also presented. The model has been tested in a 2 m wave flume for various wave frequencies and wave heights of regular waves. The model is also analysed using a computer program developed, and the comparison of theoretical results with the experimental results is presented.