Topology optimization of offshore structures based on successive iteration of analysis and design under random excitation

Offshore engineering structures are subjected to complex and extreme random wind-wave-current conditions, making their performance safety and functional effectiveness crucial considerations in structural design. However, the random response analysis of such complex systems often entails a substantial computational burden, which poses significant challenges to the efficiency and convergence of topology optimization under random excitation. This study proposes an efficient topology optimization framework for offshore structures under random excitation environments. Herein, a random response optimization strategy that alternates analysis and design in successive iterations is introduced. The pseudo excitation method (PEM) is adopted to efficiently solve the random response. In the optimization model, the root mean square (RMS) displacement of the dynamic response at a critical location is adopted as the objective function. The sensitivity of the structural random response is derived from the adjoint method, and the method of moving asymptotes (MMA) optimization algorithm is employed to solve the problem. The proposed method is demonstrated to significantly improve optimization efficiency and achieve stable convergence. Optimization design cases involving different offshore structures further illustrate the potential applicability of this method for real-world structures subjected to complex random loads.