Introduction

Abstract

As offshore oil production moves into deeper water, compliant structural systems are becoming increasingly important. Examples of this type of structure are tension leg platforms (TLP’s), guyed tower platforms, compliant tower platforms, and floating production systems. The common feature of these systems, which distinguishes them from conventional jacket platforms, is that dynamic amplification is minimized by designing the surge and sway natural frequencies to be lower than the predominant frequencies of the wave spectrum. Conventional jacket platforms, on the other hand, are designed to have high stiffness so that the natural frequencies are higher than the wave frequencies. At deeper water depths, however, it becomes uneconomical to build a platform with high enough stiffness. Thus, the switch is made to the other side of the wave spectrum. The low natural frequency of a compliant platform is achieved by designing systems which inherently have low stiffness. Consequently, the maximum horizontal excursions of these systems can be quite large.