Finite element modeling of punching shear behavior of ultra high performance fiber reinforced concrete slabs considering effect of fiber orientation

The present study represents a numerical study on the punching shear behavior of ultra-high performance steel fiber reinforced concrete (UHPFRC) slabs without shear reinforcement, particularly considering the effect of fiber orientation, validated by experimental results. In recent decades, ultra-high performance steel fiber reinforced concrete (UHPFRC) has been a new achievement in concrete technology. Due to its superior mechanical properties, civil engineers can address the problem of punching shear of thin slabs that are currently widely used in buildings. By processing some studies, researchers have found that the strength capacity of the material before cracking and the post-cracking resistance strongly depend on the orientation of the fibers, which heavily rely on the casting direction and casting method. While most of previous studies focused on the effect on the behavior of beams, the present research particularly considers how the casting procedures as well as the volume content of the fiber affect the punching shear behavior of flat slabs.Based on models from the previous research and this research’s experimental results, constitutive model of material was proposed to capture the effects of fiber orientation. Different parts of the slab according to different distances from casting positions produce different fiber orientations, and lead to different material models, particularly tensile constitutive models. The material models were applied to finite element analysis in ABAQUS/Explicit, using Concrete Damage Plasticity model to simulate the punching shear behavior of the flat slabs. The appropriation of proposed material models and finite element modeling procedure were validated by comparing to experimental results. Consequently, these models can be used further to consider the effect of fiber orientation in future researches and utilizations of UHPFRC structures.