Conference Agenda

Crack width control is essential for the serviceability of reinforced concrete (RC) structures, yet current design models rely on simplified assumptions that fail to capture strain localization and material heter-ogeneity. This study investigates uncertainty in crack width predictions using a finite-element model based on smeared crack and fracture mechanics approaches. The model incorporates the crack band concept to ensure mesh-objective energy dissipation and addresses limitations of experimental measurements, such as single-face observations and the exclusion of microcracks. Validation against experimental results of RC elements sub-jected to bending and direct tension examines the influence of mesh size, bar modeling, and concrete heteroge-neity represented by random fields. The verification demonstrates that 3D modeling with embedded bars and an imposed minimum crack band size significantly improves prediction accuracy, achieving model uncertainty close to unity for maximum crack width. The findings provide practical guidance for applying smeared crack models in the serviceability verification of RC structures.

Concrete is widely used but limited by its brittle behaviour and low tensile strength. Fibre-reinforced concrete (FRC) improves crack resistance, ductility, and tensile performance, yet its microstructural mechanisms remain insufficiently understood. This study uses the DEM code YADE to model concrete as a two-phase material and analyse the pull-out behaviour of fibres. Fibres were represented with real geometry, either rigid or deformable. Simulations were compared with experimental data, highlighting the role of interface stresses, and fibre deformability. The results demonstrate DEM’s effectiveness in capturing fibre-concrete interaction.

In this contribution, a model-based investigation is conducted to correlate fiber orientation measures with the post-cracking strength of Fiber-Reinforced Concrete (FRC), thereby providing guidance for the engineering design of FRC structures. For this, a multi-level model for the analysis of FRC structures is used, which allows to assess the influence of a chosen fibre type, content, and orientation on the structural response. Using data from segmented CT images, the effects of the fiber orientation, fiber content and embedment length on the fiber bridging stress are quantified. After providing an overview of models describing the fiber orientation state and their relation to experimental measurements, the model is validated by the re-analysis of 3-point bending tests, using the fiber orientation state from segmented CT images as explicit model input. Additionally, assumption-based predictions using different orientation tensors are carried out to discuss the influence of incomplete information. A parametric study quantifies the discrepancy between post-cracking strengths obtained
from standard FRC characterization tests and the post-cracking strength expected in the to-be-designed structural member due to differences in fiber orientation. The results demonstrate how the fiber orientation state governs the post-cracking performance and provide practical guidance for incorporating orientation effects in the design of FRC structures.

Corrosion-induced cracking is a leading cause of durability loss in reinforced concrete structures exposed to chloride environments. Existing numerical models often assume uniform rust expansion or treat chloride diffusion and mechanical cracking as sequential processes, limiting their ability to capture spatially heterogeneous corrosion patterns. This work presents a finite element framework that couples chloride transport with mechanical model describing cracks together with concentration triggered rust expansion and crack-enhanced diffusion. Using the thermal analogy in Abaqus with user subroutines, the approach enables non-uniform corrosion to develop naturally in response to local chloride concentration. A smooth activation function captures the progressive filling of the porous zone before expansive pressure develops. The framework implements bidirectional coupling where mechanical cracking accelerates chloride ingress through crack width dependent diffusion, creating a self-accelerating deterioration process. The model was validated against experimental results from accelerated corrosion tests, successfully reproducing both non-uniform rust distribution and characteristic crack patterns. While the formulation assumes two-dimensional sections and neglects electrochemical kinetics, satisfactory agreement with experiments demonstrates that essential features of chloride-induced deterioration can be captured using this simplified approach.

This paper validates a computationally efficient 2.5D approach for modelling cohesive discrete cracks in concrete at the mesoscale. The proposed method relies on extracting a series of planar, two-dimensional slices from a full three-dimensional geometry and coupling them through horizontal and vertical springs that transfer force interactions between adjacent layers. The main objective of this approach is to effectively reconstruct the essential three-dimensional mechanical response while maintaining the computational efficiency of two-dimensional analyses. The validation is performed using two benchmark configurations: a dogbone-shaped tensile specimen and a notched three-point bending beam, both featuring stochastically generated mesostructures with ellipsoidal aggregates. Key model parameters are systematically examined, and mesh-sensitivity analyses ensure solution objectivity. The study conducts comprehensive performance comparisons between isolated 2D models, the proposed 2.5D layered approach, and full 3D simulations to evaluate crack-propagation patterns, force–displacement and computational efficiency. The results demonstrate that the 2.5D approach achieves an optimal balance between accuracy and computational cost, making it a practical alternative to full three-dimensional simulations for mesoscale concrete fracture analysis.