Reliability Based Earthquake Design Guidelines for Marine Structures

This paper describes a reliability based formulation to determine earthquake LRFD parameters for conventional, steel, pile supported, tubular member platforms that is proposed as a basis for earthquake design criteria and guidelines for offshore platforms and that is intended to have worldwide applicability. The formulation is illustrated with application to platforms located in five areas: offshore California, Venezuela (Rio Caribe), the East Coast of Canada, the Caspian Sea (Azeri), and the Norwegian sector of the North Sea. The approach and proposed quantifications have been verified with site specific results from four locations. Good agreements have been developed between the site specific results and those based on these guidelines. The approach provides an important element of information sensitivity that allows the loading and resistance factors to be varied as a function of the desired reliability for a platform, the unique aspects of its seismic environment, and the primary uncertainties in the earthquake loadings and platform element capacities.