Conference Agenda

This paper extends the discussion on critical numerical objectivity issues in finite element analysis of reinforced concrete beam elements, highlighted in previous studies by the authors. We address these challenges using enhanced displacement-based beam finite element models that incorporate bond-slip effects, warping deformation modes, and fracture energy regularization. The introduction of enriched kinematics aims to reduce mesh dependency and more accurately capture localized damage, particularly cracking phenomena. Comparative numerical simulations demonstrate the limitations of classical beam elements and the advantages provided by the enhanced ones, laying the groundwork for future developments in force-based models.

The prediction of the resistance of concrete anchors is essential for ensuring the safety of sensitive infrastructures. This study proposes the use of an energetically regularized damage model in tension and compression (RTC), based on an extended version of Mazars' model. In addition to regularization, modifications have been made to better capture material behavior, particularly in compression, to simulate the pull-out tests of anchors. Finite element simulations using the Cast3M software are employed to analyze concrete cracking, considering both the behaviors of concrete and steel. The simulation results reveal two main failure modes: the formation of a concrete breakout cone or steel fracture. The first part of the study compares the results of experiments from the literature with simulations based on embedment length. The second part focuses on a sensitivity study of various parameters, including embedment length and plate stiffness. It appears that embedment length is a highly influential factor in the resistance of concrete anchors, and that anchor geometry can also have a significant impact.

Concrete Cone failure of fasteners remains a challenging engineering problem in numerical simulation due to the mixed-mode fracture. For this reason, design of fasteners still heavily depends on empirical design rules from standards which come with limitations in applicability. One less researched influencing factor in numerical simulations of CC-failure is the compressive fracture energy of concrete. In this paper, a numerical study is carried out in the commercial Finite-Element software ANSYS® Mechanical using Drucker-Prager model with Rankine’s criteria for concrete. The influence of fracture energy under compression on the ultimate load and load-displacement behavior of fasteners under CC-failure as well the mesh-sensitivity is studied for two embedment depths. Strong influence of the compressive fracture energy on the ultimate load, load-displacement behavior and fracture pattern in the simulations could be identified.

Heterogeneity of concrete originates in the production process, which consists of bonding aggregates together with a matrix of a binder. The presented meso-scale model can provide the much valuable information about the fracture process at the level of aggregate to cement matrix bond. It therefore aims to describe one of key properties of concrete that is the strain-softening behaviour as a response to mechanical loading. The detail of stress analysis is deeper compared to the discrete models as their description of the inter-particle interaction tends to average out the possibly important stress concentrations. The presented MFEM modelling approach accepts the higher solution costs, relying on modern High-Performance Computing (HPC). In return, a detailed description especially of the stress field and material damage within the material phases and interfaces can be obtained.