ABSTRACT

Assessment of reliability of offshore marine hydraulic structures under seismic impacts is carried out in two stages. The first stage is analysis of seismic impacts. The analysis of seismic impacts includes sequential analysis of site response, structure and soil interaction and structure response. Determination of the site response allows to define accelerations of the free soil surface without structure. The analysis of structure and soil interaction is used to calibrate structure response model. The analysis includes careful evaluation of structure and soil interaction with use of a detailed soil model and a simplified structure model. Analysing seismic response of the structure it is possible, on the contrary, to use a simplified model of the foundation with concentrated parameters, frequency dependent rigidity and attenuation and with added water masses. The model has been carried out on the base of structure and soil interaction analysis. Detailed model of the structure can also be used in seismic response analysis. The second stage is the use of a probabilistic model based on reliability assumption as a probability of preserving in time the possibility to fulfil the required functions in the specified regimes and conditions of structure operation.

INTRODUCTION

At present five large deposits have been explored in the Sakhalin shelf. Here the works on the projects of Sakhalin I and Sakhalin II have begun. Their realisation is difficult because of hard natural conditions and high seismicity of the region.

The offshore fixed platforms are now unique objects of designing and construction from the point of view of their design and natural conditions of their location. Therefore the current Russian norms and regulations are not quite applicable to them. The reliability assessment of offshore marine hydraulic structures is carried out in two stages.

This content is only available via PDF.
You can access this article if you purchase or spend a download.