Behavior of stiffened deck plates under hydrocarbon fire

Hydrocarbon fire accidents in offshore deck structures are of serious concern due to the confined environment of offshore oil drilling and production platforms, which limits the escape routes. One of the major structural components that are highly affected during fire accidents is the deck plates. The deck plates are usually designed as stiffened plates with high strength steel. The increase in temperature during fire changes the mechanical properties of steel significantly, which may result in strength and geometric instability of the structure. The present study aims to investigate the behavior of a stiffened steel deck plate under different hydrocarbon fire scenarios using sequential thermal and structural analyses using Ansys. The stress distribution and deformation of the plate in time scale are presented, discussing the highly affected region concerning the source of the fire. The fire rating for the steel deck under hydrocarbon fire is also suggested for different fire scenarios considered in the study. It was observed that the deformation of the deck plate varies to the area of deck plate in direct contact with fire, boundary conditions of the plate, and the area of steel plate with elevated temperature beyond which the mechanical properties of steel are highly affected. Also, the numerical investigations of the deck plate under the combined action of mechanical load and hydrocarbon fire had shown an increased deformation in the deck plates, which in turn reduces the fire rating of the plate under all fire scenarios. The effect of creep strain at high temperature on the response of the steel deck plate is also studied for the different fire loading cases.