Environmental and structural data from a monitoring system installed on a steel jacket platform in the Sicily channel has been examined for reliability. Significant data has been chosen to assess the design assumptions for the dynamic behaviour of the platform such as added mass, marine growth and axial pile group stiffness. A parametric structural dynamic identification is achieved by the modal parameter technique, comparing the theoretical and experimental response of the platform.
This paper is concerned with a dynamic study of the Vega steel jacket platform. The significant uncertainties connected with mathematical modelling and their influence on the predicted structural response are investigated. Recently the comparison between the design hypotheses and the structural response of offshore structures has been performed using the information collected by monitoring existing platforms. This study is carried out using experimental data recorded from a steel jacket platform in the Mediterranean to obtain the dynamic identification of the platform using a simplified numerical model of the structure. Experimental results have always made a significant contribution to the development of structural analysis and design, and form the most effective method of research in the study of complex physical phenomena and in the formulation of suitable empirical laws to model them. But in the last few years a substantial change has occurred which results from the introduction of new and very effective techniques to analyse the structures, increasing the types of structures which can be handled directly by numerical methods. However such methods can not replace the role of experimental analysis, which is fundamental to the knowledge of structural behaviour. In structural analysis there are two basic approaches. The first is called "direct", where stresses and strains in a structure are determined on the basis of definition of external loads.
