Assessing the Behavior of Fixed Offshore Jackets in Failure Condition, Evaluation in Ultimate State to Improve Structural Safety

ABSTRACT The safety of offshore fixed jacket platforms is a critical concern in offshore engineering, given their vulnerability to extreme environmental conditions and operational stresses. Despite ongoing advancements, the structural integrity of these platforms remains a challenge, particularly under failure conditions induced by storms or other severe environmental loads. This study aims to assess the failure modes and structural resilience of four offshore jacket platforms from the South Pars Gas Field, using pushover analysis to simulate the response of these platforms under both operational and storm conditions. The motivation for this research stems from the increasing frequency of structural failures in offshore platforms, underscoring the need for improved safety standards and proactive maintenance strategies. Our primary objective is to identify key structural vulnerabilities and propose design enhancements to improve safety margins and extend the service life of existing platforms. We examine the behavior of these platforms under various load combinations, focusing on failure mechanisms such as deck toppling, excessive deformation, and buckling of the structural members. Key findings indicate that safety factors for the platforms under typical operational conditions range from 1.85 to 2.5, which is below the desired safety threshold of 3.0 for new platforms. Proposed reinforcement strategies, including increasing member thickness and adjusting bracing configurations, resulted in significant safety improvements, with some platforms demonstrating up to a 45% increase in safety factors and improved ductility.