Numerical analysis and preliminary design of topside of an offshore platform using FGM and X52 steel under special loads

Abstract

This study investigates the behavior of the topside of an offshore platform under hydrocarbon explosion and wind. Topside is designed for a combination of loads arising from types of equipment, fixed and rotating machinery, and cranes, apart from the gravity loads. While the wind loads are calculated using a gust factor and applied at different levels of the deck, a preliminary analysis is carried out using SAP2000 nonlinear. The design check carried following the code confirmed that the chosen sections satisfy the design requirements, both in strength and serviceability criteria. The topside of a typical offshore platform is highly vulnerable to fire and hydrocarbon explosion, causing extreme pressure and temperature in the confined areas. Pressure caused by the hydrocarbon explosion is rapid and results in an impulsive force of short duration. It damages the structural components and affects the overall performance of the topside considerably. The blast load is applied as an overpressure on the beams and columns and analyzed using ABAQUS explicit. The current study investigates the structural adequacy of members, constructed with X52 steel and functionally graded material (FGM). A comparison of the results showed that FGM offers more resistance to the displacement of beams and columns. Under the action of blast overpressure, members with FGM showed a significant reduction in both the plastic stain and Von-Mises stress at the beam–column connections in comparison with that of X52 steel.