Topology Optimization of Mudmat Design Based on Bottom Stability Analysis of a Three-Legs Jacket Structure

Abstract The initial stage in the installation of a jacket structure involves the jacket floating towards the seabed surface before being permanently anchored with piles. During this pile-free stage, the mudmat serves as a critical temporary foundation to maintain the stability of the jacket structure. On Bottom Stability (OBS) analysis is essential at this stage to ensure the structure’s stability. The structural footing component integral to the OBS analysis is referred to as the mudmat. Given the mudmat’s crucial role as a temporary foundation, its design and dimensions must be carefully considered in the structural design process. Consequently, topology optimization is performed to optimize the load distribution path and dimensions, thereby achieving the optimum weight. In this study, mudmat topology optimization was conducted locally by reducing the material distribution to minimize strain energy. The optimization results were then interpreted to derive a feasible design. The study yielded two optimized mudmat designs with material distributions of 30% and 20%. These designs exhibited a smaller Factor of Safety (FoS) compared to the initial design. Specifically, the FoS reduction in the OBS analysis for bearing criteria in designs 1 and 2 was 59% and 50%, respectively, overturning 43% and 21%, and sliding 67% and 59%. Nevertheless, both designs met the OBS criteria, with FoS values exceeding the thresholds of >2 and 1.5. Results show reduction structural weight up to 40% and 29%, for design 1 and 2, respectively.