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<p>Aggregate strength plays a crucial role in determining the fracture behavior of concrete, particularly under dynamic loading conditions. Herein, a three-dimensional discrete element method (DEM) framework was proposed to analyze the effect of aggregate strength on dynamic splitting tensile fracture behavior of concrete. Firstly, a three-phase mesoscale model including mortar, crushable aggregates with realistic morphology, and interfacial transition zone (ITZ). And then, the conventional flat-joint model was enhanced by accounting for strain rate effects, providing precise simulations of the relationship between aggregate strength and dynamic splitting tensile behavior. On this basis, numerical simulation of splitting tensile tests was carried out on concrete with varying ratios of aggregate-to-mortar strength (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({\sigma }_{\text{agg}}/{\sigma }_{\text{mor}}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>σ</mi> <mtext>agg</mtext> </msub> <mo stretchy="false">/</mo> <msub> <mi>σ</mi> <mtext>mor</mtext> </msub> </mrow> </math></EquationSource> </InlineEquation>=0.7, 1.0, 1.5, 2.0, and 2.5) under different strain rates (10<sup>–5</sup>/s ~ 100/s). The results revealed that post-peak behavior exhibits brittle failure characteristics at 10<sup>–5</sup>/s and 10<sup>–1</sup>/s, transitioning to ductile failure at 10/s and 100/s. A significant inverse relationship was observed between strain rate and the influence of aggregate strength on splitting tensile strength––this impact diminishes progressively with both increasing strain rate and higher aggregate strength at constant strain rates. Microstructural analysis revealed that enhanced aggregate strength correlates with reduced microcrack formation in aggregates, whereas microcrack density in both ITZ and mortar phases exhibits an increasing trend. These comprehensive simulation results facilitated the development of a modified dynamic increasing factor model for splitting tensile strength, which systematically incorporates both strain rate effects and aggregate strength parameters.</p>

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3D DEM framework for simulating the influence of aggregate strength on the dynamic splitting tensile fracture behavior of concrete

  • 期刊论文

  • 发表日期：

    2025年6月2日

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  • Xia Li,
  • Yuanjie Liang,
  • Yinuo Qian

摘要

Aggregate strength plays a crucial role in determining the fracture behavior of concrete, particularly under dynamic loading conditions. Herein, a three-dimensional discrete element method (DEM) framework was proposed to analyze the effect of aggregate strength on dynamic splitting tensile fracture behavior of concrete. Firstly, a three-phase mesoscale model including mortar, crushable aggregates with realistic morphology, and interfacial transition zone (ITZ). And then, the conventional flat-joint model was enhanced by accounting for strain rate effects, providing precise simulations of the relationship between aggregate strength and dynamic splitting tensile behavior. On this basis, numerical simulation of splitting tensile tests was carried out on concrete with varying ratios of aggregate-to-mortar strength ( \({\sigma }_{\text{agg}}/{\sigma }_{\text{mor}}\) σ agg / σ mor =0.7, 1.0, 1.5, 2.0, and 2.5) under different strain rates (10–5/s ~ 100/s). The results revealed that post-peak behavior exhibits brittle failure characteristics at 10–5/s and 10–1/s, transitioning to ductile failure at 10/s and 100/s. A significant inverse relationship was observed between strain rate and the influence of aggregate strength on splitting tensile strength––this impact diminishes progressively with both increasing strain rate and higher aggregate strength at constant strain rates. Microstructural analysis revealed that enhanced aggregate strength correlates with reduced microcrack formation in aggregates, whereas microcrack density in both ITZ and mortar phases exhibits an increasing trend. These comprehensive simulation results facilitated the development of a modified dynamic increasing factor model for splitting tensile strength, which systematically incorporates both strain rate effects and aggregate strength parameters.