Design and optimization of a fiber mesh-reinforced concrete thin-shell hull: An integrated material property–beam stiffness calculation–fem stiffness allocation method

This study addresses the lack of an integrated workflow linking material design, hull geometry, and composite-shell stiffness allocation through a hierarchical design and optimization route for a fiber-mesh-reinforced concrete thin-shell hull. The material system is first organized as a decorative–structural–decorative sandwich lightweight cementitious composite, so that the requirements for appearance, density control, and load bearing are not forced onto one concrete mix. Euler–Bernoulli beam theory is then used to obtain a preliminary estimate of the hull's overall flexural-stiffness demand. After this step, a three-dimensional composite-shell finite element (FE) model is established in ABAQUS ^® to compare how stiffness should be shared between the fiber-reinforced concrete (FRC) layers and the PAN-based, standard-modulus carbon fiber mesh (CFM) layers. The parametric results show a clear change in the load-sharing mechanism as the CFM stiffness fraction varies. In particular, the CFM stiffness fraction controls the tension-sharing relationship between the FRC matrix and the reinforcement layer, making it the primary design variable. The 3:8:3 FRC layer distribution gives a better compromise between stiffness gain and areal-density control than the other two layer ratios. Considering density, overall stiffness, and reinforcement-layer stress together, the B3 M scheme is selected; it has a total wall thickness of 8 mm, an FRC layer ratio of 3:8:3, and a CFM stiffness fraction of 40%. Under a unified supported boundary condition across all load cases, this scheme gives a maximum displacement of 36.24 mm in the three-person male case and a mid-span von Mises stress of 4.27 MPa in the four-person mixed control case. The proposed route, which combines material functional layering, preliminary beam-theory design, FE layup optimization, and multi-condition verification, offers a practical reference for lightweight cementitious thin-shell floating structures.