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

2013 ◽  
Author(s):  
Jeom Kee Paik ◽  
Jerzy Czujko ◽  
Jeong Hwan Kim ◽  
Sung In Park ◽  
Shafiqul Islam ◽  
...  
Keyword(s):  
Cfd Simulation ◽  
Thermal Response ◽  
Structural Response ◽  
Fire Risk ◽  
Response Analysis ◽  
Nonlinear Structural ◽  
Offshore Installations ◽  
Fire Loads ◽  
Structural Responses ◽  
Nonlinear Structural Response

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.

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

2014 ◽  
Author(s):  
Jeom Kee Paik ◽  
Jerzy Czujko ◽  
Sang Jin Kim ◽  
Jong Chan Lee ◽  
Bong Ju Kim ◽  
...  
Keyword(s):  
Structural Response ◽  
Response Analysis ◽  
Shell Elements ◽  
Nonlinear Structural ◽  
Offshore Installations ◽  
Industry Practice ◽  
Design Values ◽  
Structural Responses ◽  
Explosion Accidents ◽  
Nonlinear Structural Response

This paper is a sequel to the previous two papers by the authors presented at SNAME annual meetings in 2012 and 2013. The key tasks for measuring and managing risks associated with hydrocarbon explosions include defining explosion loads and computing structural responses. In industry practice, such response analysis often involves applying uniformly distributed explosion loads to structures according to their nominal design values. However, uniformly distributed loads based on nominal values of structural design may not always fully reflect the actual situations of real explosion accidents, mainly because the actual characteristics of both explosion loads and structural responses are extremely nonlinear. Therefore, it is highly desirable to identify the non-uniform distributions of explosion loads and directly apply them to structures for the response analysis. To accomplish this, technical challenges must be met in terms of refined computations for loads, structural responses and interfaces between load definitions and structural analyses. This study develops a new procedure to resolve such challenges. In this procedure, FLACS computational fluid dynamics (CFD) simulations are applied to the characterization of blast loads. ANSYS/LS-DYNA nonlinear finite element methods (using plate-shell elements) are applied for nonlinear structural response analysis, and a computer program named FLACS2DYNA is developed to automatize the direct export of the FLACS simulations to the ANSYS/LS-DYNA computations. The contribution of this study is demonstrated through an applied example using a hypothetical topside structure of a VLCC-class FPSO that is exposed to hydrocarbon explosions. This example shows that the developed procedure can enable fast, accurate and reliable nonlinear structural response analysis, and subsequently allow better assessment and management of explosion risks.

Nonlinear Structural Consequence Analysis of FPSO Topsides Under Fire

2012 ◽  
Author(s):  
Jeong Hwan Kim ◽  
Du Chan Kim ◽  
Cheol Kwan Kim ◽  
Md. Shafiqul Islam ◽  
Jeom Kee Paik
Keyword(s):  
Structural Response ◽  
Fire Risk ◽  
Offshore Structures ◽  
Nonlinear Material ◽  
Response Analysis ◽  
Element Analysis ◽  
Practical Procedure ◽  
Consequence Analysis ◽  
Nonlinear Structural ◽  
Structural Consequence

This study aims to develop a practical procedure for the nonlinear structural consequence analysis of structures under fire. The thermal and structural response analysis have been performed in this study using a commercial nonlinear Finite Element Analysis (FEA) code. The results of the structural response analysis are then compared to the experimental results. This study concludes by presenting methods for fire load applications and nonlinear material modeling. The insights offered by the modeling techniques and analysis procedures presented in this study should be very useful and practical in the fire risk assessment of offshore structures.

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