PSI - Issue 79

Mansi Gupta et al. / Procedia Structural Integrity 79 (2026) 259–265

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shorter than the model with polygonal aggregates and the actual laboratory results. The results imply that among the three shapes, irregular polygonal shapes are best suited for representing aggregates in the mesoscale geometry. These results highlight the role of aggregate morphology in fracture behavior of concrete.

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(c) Fig. 5. Load-CMOD plots for (a) small, (b) medium, and (c) large beams and their comparison with corresponding experimental data (Bhowmik and Ray, 2019) The aggregate packing fraction or the volume content also plays a crucial role in the fracture behavior of concrete. The results from different packing fractions indicate that for more volumetric content, the initial elastic stiffness of the model improves. However, this observation is accompanied by decrease in peak load of the specimens, as more number of aggregates introduce more ITZ length in the concrete specimen. The larger proportions of ITZ acts a preferable site for damage localization and crack propagation, leading to reduced strength of material. The results for varying beam sizes reveal that the mesoscale model is not only capable of capturing the internal heterogeneities, but the size dependency of the structure is also accurately captured. The experimental trends for load-CMOD curves for a set of geometrically similar beam are precisely captured by the mesoscale simulations. The peak load of the beam increases with the increase in specimen size, indicating an increase in FPZ length (Bhowmik and Ray, 2019). Overall, results denote that the mesoscale approach bridges the gap between microstructural characteristics and the macroscopic fracture response of the structure. 4. Conclusions A two-dimensional mesoscale model consisting of mortar, aggregate and interfacial transition zone has been successfully modelled using cohesive elements in finite element method. Based on the results of mesoscale modelling of concrete beams, following conclusions can be drawn:  The results of parametric analyses reveal that variations in aggregate content strongly affect the macroscopic stress–strain behavior and failure mechanisms in the concrete.