A New Procedure for the Nonlinear Structural Response Analysis of Offshore Installations in Fires

The quantitative assessment and management of the risks associated with fire require integrated computations of fire loads and their consequences. The objective of this paper is to present a new procedure for the nonlinear structural response analysis of offshore installations during fires. The procedure comprises calculation of fire loads using computational fluid dynamics (CFD) simulation, thermal response analysis and nonlinear structural response analysis in fire which are key elements in the framework of the fire risk assessment and management. KFX code is used to perform the fire CFD simulation; whereas the analyses of both thermal and nonlinear structural responses are performed using the LS-DYNA code. Models for such analysis can be developed with shell elements to represent the structures with required accuracy. A computer program known as KFX2DYNA is applied to automatically import the results of the KFX simulations which are directly exported to LSDYNA for the analyses of both heat transfer and nonlinear structural responses, making fire risk analysis fast, accurate and reliable. An experimental scenario with a simply supported I-girder under fire is used to validate the procedure. The applicability of the procedure is demonstrated using the example of a fire in the hypothetical topside structure of a VLCC-class FPSO.