ABSTRACT
The discovery of oil and gas in the Black Sea offshore platform and the various problems brought about by its extraction in the seventies have marked a new direction of development in the field of structural analysis and design. Also the use of steel tubular structures was not a new problem in the structural computation, the offshore conditions imposed on them were a challenge to most of those involved in structural analysis and design. An important component of the novelties in the field is the fatigue behaviour of the structural joints due to mainly the cyclicity of the loadings and, also, due to the environmental conditions. On top of this, an offshore structure challanges the structural engineer with its huge number of nodes and bars. The study presents some aspects of detecting the structural damages by comparing the values of parameters that govern the dynamic behaviour of the structure. The comparison requires the setting up of a Data Base containing initial values of the parameters computed on the undamaged structure and automatically measured and stored values of the same parameters. The new approach is presented from both points of view: theoretical investigation using a FEM technique and experimental investigation using the ERM technique proposed by the authors.
