Investigation of the pitch motion of a semi-submersible offshore platform combining conventional mooring systems using genetic algorithms

Kazemi, Saeid; Azizi, Farshid; Azarsina, Farhood

doi:10.22034/ijcoe.2025.529014.1185

Investigation of the pitch motion of a semi-submersible offshore platform combining conventional mooring systems using genetic algorithms

Document Type : Original Research Article

Authors

Saeid Kazemi ¹

Farshid Azizi ²

Farhood Azarsina ²

¹ Department of Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran

² Department of Engineering, Science and Research Branch, Islamic Azad University

10.22034/ijcoe.2025.529014.1185

Abstract

The Mooring systems play a significant role in the hydrodynamic behaviour of the floating offshore platforms. This research examines the role of mooring systems in regulating the pitch motion of semi-submersible platforms, given their growing application in deep-water operations. Excessive platform movements can compromise structural stability and operational performance. To analyze platform motion, numerical simulations of the AmirKabir semi-submersible platform were conducted under various mooring configurations using nonlinear time-domain analysis. Two optimization approaches were employed: a numerical trial-and-error method and a genetic algorithm based on stochastic selection, both utilizing numerical modeling to define the fitness function. The predicted outcomes from the genetic algorithm align with those obtained from numerical methods in reducing platform pitch motion. Three mooring configurations derived from the genetic algorithm demonstrate an approximately 32% improvement over numerical models. The results indicate that combining catenary and taut mooring lines yields optimal behavior in controlling the pitch motion of semi-submersible platforms.

Keywords

Catenary mooring

Taut mooring

Semi-submersible platform

Optimization motion response

Genetic Algorithm

Subjects