Design Methodology and Mechanical Behavior of Prestressed Modular Box-Type Foundation

To address the limitations of traditional cast-in-place foundations, such as long construction cycles, high material consumption, and extensive on-site wet operations, this study develops a prestressed modular box-type foundation suitable for heavy load-bearing structures. A refined three-dimensional finite element model was established using Midas FEA NX 2025 software to systematically investigate the mechanical response of the structure under self-weight, concentrated live loads, pavement loads, and prestressing forces. The model comprehensively accounts for material nonlinearity, prestress effects, and foundation–soil contact nonlinearity. The results demonstrate a uniform stress distribution within the proposed foundation. Under combined load cases, the maximum tensile stress of the concrete is 0.97 MPa, which is significantly lower than the design tensile strength of C35 concrete. The application of prestressing forces effectively inhibits the initiation and propagation of cracks, with only negligible localized micro-cracks observed on the top surface of the foundation. Furthermore, the maximum vertical displacement is 1.17 mm, corresponding to a deflection ratio of 1/1709.4. These values are well within standard limit requirements, demonstrating adequate structural stiffness under the simulated conditions. This study provides a crucial numerical analysis basis and engineering design reference for the broader application of modular prestressed foundations in civil engineering and prefabricated industrial structures.