Residual Strength Assessment of Semi-Submersible Platform Column Due to Supply Vessel Collision

The new structural concept of semi-submersible oil and gas production platforms is based on column square cross sectional area. A successful design is strongly dependent on optimized column structural arrangement. The columns are constituted of longitudinal stiffened panels having their ultimate strength characterized by buckling under compressive loads. A structural damage which may occur in these columns is the effect caused by supply vessel collision. Normally, such damage is in the form of local dents. The aim of the present paper is to evaluate the ultimate buckling residual strength of typical column of semi-submersible platforms damaged by a supply vessel collision. The buckling analysis was validated using a finite element model considering geometric and material nonlinearities considered in previous correlation studies with small scale experiments. Residual strength results from the damaged column are compared with the ultimate strength of equivalent intact column to estimate the safety margin associated with the column structural capability after supply vessel collision.