A Method for Estimating Global Sectional Loads from Local Point Strain Monitored on Real Ship Hull Structures

The real-time monitoring of global sectional loads is crucial for the safety assessment of ship hulls during operation, yet it remains a significant challenge due to the complexity of the structure and the marine environment. Direct measurement of hull global sectional loads remains difficult in practical engineering, whereas local strain responses can be conveniently obtained using strain gauge. This paper presents an analytical physics-driven load conversion framework to reconstruct global sectional load components from limited longitudinal strain measurements for full-scale ship hull structures. A load conversion matrix is established based on a linear superposition of strain components from vertical bending, horizontal bending, axial force, and warping torsion. The method is first validated on a simplified U-shaped beam using finite element analysis, identifying optimal sensor arrangements. It is then extended to a uniform beam with the complex midship section of a 21,000 TEU containership, where its accuracy is further confirmed under both static and dynamic periodic loading conditions. Finally, the proposed method is validated against CFD-FEM coupled simulation results for the containership under regular head waves and oblique short-crested irregular waves. This study provides a feasible analytical tool for reconstructing hull girder sectional loads using sparse local strain monitoring data, which can be used in applications such as full-scale ship structural health monitoring and global strength assessment.