Failure Analysis and Safety Assessment of Offshore Platform under Different Ship Collision Scenarios by Numerical Simulation

Quantitative safety assessment of offshore platforms under ship collision is a hot topic. Numerical simulation is a powerful tool to evaluate the damage and failure mode of offshore structures under collision. This paper incorporates an element-coupling method into the simulation of ship-platform collision, in which the jacket platform is established using different elements to reduce the modelling costs of the traditional pure shell element modeling method. The coupling method for connecting the interfaces of different elements is proposed and validated through a case study. Further, numerical simulations are carried out for different collision scenarios with collision velocity from 1 to $5\mathrm{m}/\mathrm{s}$. According to the simulation results, three different types of failure modes of the jacket are identified namely as “Local denting,” “Brace buckling,” and “K-joint rupture” corresponding to low-energy collision, medium-energy collision, and high-energy collision scenarios, respectively. Also, the detailed failure mechanism of the collision area under a typical high-energy collision is assessed. The collision process is divided into six stages according to the analysis of collision force results. The safety of the jacket platform under collision is assessed through the overall results of vibration acceleration and horizontal displacement. The work in this paper can greatly reduce the modeling efforts and calculating costs, and is thus suitable for conducting numerical analysis of failure mode and collision process in a more efficient way.