Dynamic response of compliant offshore structures - Review

Offshore compliant structures such as guyed platforms, tension leg platforms and articulated towers are economically attractive for deep-water conditions because of their reduced structural weight compared to conventional platforms. The foundations of these kinds of structures do not resist lateral environmental loads forces; instead, restoring moments are provided by a large buoyancy force, a set of guylines or a combination of both. These structures have a fundamental frequency well below the ocean wave's lower frequency bound. As a result of the relatively large displacements, geometric nonlinearity is an important consideration in the analysis of such a structure. This paper presents a literature review on offshore compliant structures. Our purpose for this paper was to primarily explore the various modeling approaches used by workers worldwide to better understand the behavior of such structures. The review focuses on the static and dynamic response of the structure due to various environmental conditions, such as wind, waves, and current. Emphasis is placed on modeling techniques and methods of solution. Many modeling and analysis techniques are common to the aerospace and ocean engineering communities due to the similarities in structural and environmental complexities. For example, aerodynamic loads on offshore platforms are a significant part of any analysis. Also, fluid loading models bear great similarities to mechanistic wind loading models. It is in this vein that a review paper with the focus offshore structures is included in a journal of aerospace engineering.