Nonlinear analysis and weight optimization of living quarters for offshore jack-up rigs: A sustainable engineering approach

The living quarters (LQ) on jack-up rigs play a critical role in ensuring crew safety and operational functionality under extreme offshore conditions. This study presents a comprehensive structural engineering procedure for the design and analysis of LQ structures, addressing the absence of specific industry standards. The methodology integrates global and local load effects from critical equipment, such as helidecks and lifeboat stations, under harsh environmental conditions during wet towing. A multi-level analysis approach, including finite element analysis (FEA), nonlinear evaluations, and fatigue assessments, was employed to verify structural resilience. The study successfully validates the LQ structures against ultimate limit state (ULS), serviceability limit state (SLS), and accidental limit state (ALS) criteria. The maximum plastic strain observed under green water pressure was 3.8 %, well below the allowable threshold of 15 %, demonstrating adequate safety margins. Fatigue analysis confirmed resistance to vortex-induced vibrations (VIV), ensuring the durability of tubular members. Optimization efforts reduced LQ structural weight by 20 %, enhancing efficiency without compromising safety. The proposed procedure bridges the gap in industry standards, providing a robust framework for designing safer and more reliable LQ structures. This study advances offshore engineering practices by addressing complex loading scenarios and operational challenges, thereby supporting the development of resilient jack-up rigs capable of enduring extreme marine conditions.