Towards adaptive collision energy standards for offshore jack-up legs: A structural failure mechanics perspective

Jack-up drilling rigs play are essential for offshore oil and gas exploration, with their leg structures subjects to significant static and dynamic loads. Increasing operational demands in deeper waters and harsher environments necessitate a structural integrity assessment, particularly under accidental impact scenarios. This study conducts an advanced nonlinear finite element (FE) analysis of jack-up rig leg collisions with offshore supply vessels using high-fidelity impact modeling, explicit dynamic simulations, and strain-rate-dependent plasticity models in LS-DYNA. The study evaluates collisions at various angles and energy levels, incorporating state-of-the-art material failure criteria, adaptive meshing techniques, and energy dissipation mechanisms. Results indicate that the current 35 MJ impact energy requirement specified by DNV may not be uniformly applicable to all structural members. Particularly, in brace collisions where local plastic deformation and stress redistribution significantly influence failure patterns. These findings emphasize the need for scenario-specific collision energy thresholds and potential reinforcement strategies to enhance jack-up rig survivability. This research contributes to the development of offshore structural resilience frameworks, providing valuable insights for classification societies, offshore engineering applications, and future digital twin-based predictive models for collision risk assessment.