Examining Progressive Collapse of Framed Structures in Response to Fire and Explosion Consequence Events

Abstract

Abstract Inherent safety is well accepted in the oil and gas industry, with codes and standards' providing guidance and requirements to ensure its successful adoption. In the last decade, the offshore industry has made major shifts in ensuring the safety of personnel and asset preservation (e.g., platforms). Advances in computational power permit specialized software to evaluate safety concerns. Major safety concerns associated with offshore installations can be examined with particular attention paid to structural integrity, deformation and any impact on personnel safety (evacuation routes, temporary refuge, etc.). Specialized software tools, Fire and Heat Transfer Simulator (FAHTS) and Ultimate Strength of Framed Offshore Structures (USFOS), enhance the capabilities to evaluate the survivability of offshore drilling structures from fire and explosion loading. When structures are subject to extreme loads due to fire and/or explosion, progressive collapse analyses are frequently used to predict both the resistance of structures subject to accidental loads and the residual strength of damaged structures after such loads. Coupling 3D Computerized Fluid Dynamics (CFD) software packages with those containing Finite Element Analysis (FEA) permits the progressive collapse of offshore platforms to be assessed. Results presented evaluate structural member deformation and any subsequent collapse in and around Safety Critical Elements (SCEs) such as: escape routes, temporary refuge, and fire water pumps. When evaluating SCEs, particular attention is paid to which structural members collapse and if their failure is acceptable for the overall integrity of the structure to remain intact and specifically any effect upon the SCEs. Structural members supporting critical substructures, vessels, equipment which can lead to escalation need to be protected. Optimization of passive fire protection will be discussed for areas showing gross deformation or failure. This paper focus is on simulated heat loads from fires and blast loads from explosions. The attendant structural responses are due to thermal radiation fluxes, blast overpressures and the associated applied mechanical loads. Early identification and appropriate mitigation responses to potential fire and blast scenarios that may threaten personnel or the survivability of an offshore installation can lead to additional safety and cost benefits for operators and engineering, procurement and construction companies.