Numerical analysis of the strength and stiffness of a hollow-core slab made of high-strength rapid-hardening concrete

Abstract

High-strength, rapidly hardening concrete combines high early strength with increased structural density, making it a promising material for the efficient production of precast concrete structures. The article presents the results of numerical modeling of the stress-strain state of a reinforced concrete hollow-core slab using a volumetric finite element model implemented in the LIRA-SAPR software package. Unlike traditional approaches based on plate finite elements, this work develops a comprehensive volumetric model that accounts for the actual geometry of the voids, enabling a more accurate description of the local stress distribution within the concrete body of the structure. Given the complex topology of the slab, the finite element mesh was formed using a combined approach. During model triangulation, both six-node and eight-node volumetric finite elements were employed simultaneously to balance descriptive accuracy and computational efficiency. Physically nonlinear universal spatial finite elements were applied, with the deformation properties of concrete described by an exponential deformation law. The prestressed reinforcement was modeled using universal spatial rod finite elements, and its mechanical properties were defined by the Prandtl diagram. The calculations determined the distribution patterns of internal forces, deflections, and stresses, particularly in the region of maximum bending moment and in the anchorage zones of the reinforcement. An approximate value of the ultimate useful load was established at which the structure reaches the limit state in terms of stiffness while satisfying the strength condition. The strength assessment was performed using the Coulomb-Mohr criterion, which accounted for the complex stress state, including principal stresses, and reflected the characteristic disparity in concrete’s tensile and compressive strength limits.