Session: 02-14-03 Structural Analysis of Marine Structures 3

Submission Number: 179732

Feasibility-First Trust-Region Optimization Framework for UC-Constrained Optimization of Offshore Jacket Structures 

Abstract: As offshore oil and gas development advances into deep waters, the demand for ultra-deepwater jacket platforms continues to grow. Owing to their substantial steel tonnage, these structures present a strong imperative for weight minimization. However, repeated finite-element evaluations across multiple load cases and design checks render the optimization computationally expensive and susceptible to numerical noise. To obtain manufacturable and reliable designs under Unity Check (UC)≤1.00, this study proposes a feasibility-first discrete trust-region genetic algorithm (TR-GA) and validates it on a real jacket platform. The method performs a small-step, manufacturable search in the sizing-variable space around a feasible baseline, coupled with dimensionality-reduction and infeasibility-suppression strategies to enhance convergence efficiency and robustness. The optimization constraints are unified within the UC framework of AISC and API RP 2A, covering axial, bending, shear, tension/compression–bending interaction, and Euler buckling. Under 10 load cases and 6 environmental combinations, the proposed framework achieves a 15% weight reduction relative to a feasible baseline while satisfying UC≤1.00 across all cases and complying with manufacturing/geometric constraints. The results demonstrate stable performance in feasibility maintenance, search efficiency, and engineering deployability, indicating suitability for large-scale discrete sizing optimization of jacket structures.

Keywords: offshore jacket platforms; weight reduction; Unity Check; TR-GA; discrete sizing optimization; multi-load-case optimization.

Presenting Author: Yuhang Li Tsinghua Shenzhen International Graduate School

Presenting Author Biography: Yuhang Li is a Ph.D. student in Civil Engineering at Tsinghua Shenzhen International Graduate School (admitted in 2024). His research focuses on optimization of offshore jacket structures, with emphasis on UC-constrained discrete sizing, manufacturability-aware trust-region genetic algorithms, and efficient multi-load-case evaluation.

Authors:

Yuhang Li Tsinghua Shenzhen International Graduate School
Sunwei Li Tsinghua Shenzhen International Graduate School
Zitang Wang Offshore Oil Engineering Co., Ltd