Ultimate strength prediction for stiffened plates under combined compression, shear and lateral loads based on design diagram and machine learning model

The present study aims to establish a framework for developing a practical design diagram based on an advanced ultimate limit state (ULS) analysis methodology for stiffened plates subjected to combined loads, namely compression, shear, and lateral pressure. The proposed approach consists of two parts: the design diagram and the explicit formulation. The necessary datasets for stiffened plate scenarios were generated through comprehensive numerical parametric analyses, providing valuable insights for enhancing existing safety assessment frameworks in ocean mobility. In total, 144 sets of design diagrams were derived, representing the relationships between ultimate shear and compressive strengths under various combined loading levels for conservative design applications. Furthermore, concise design formulas for predicting the ULS of stiffened plates under combined loads were proposed using symbolic regression (SR) algorithms. Unlike black-box intelligent models or conventional curve-fitting techniques, symbolic regression provides explicit equations that achieve a balanced trade-off between accuracy, interpretability, and complexity, thereby facilitating practical engineering applications. As the combined loading conditions considered herein more closely reflect the actual loading environments of stiffened plates in ships and offshore structures, the present work serves as a meaningful extension and complement to existing ULS assessment methodologies. • Coupling loading effects on ultimate loads of stiffened plates were investigated. • An explicit-from empirical formula were proposed based on SR algorithms. • A prediction framework was established including both the formula and diagram.