Numerical　analysis　is　an　important　research　method　to　avoid　the　shortcomings　of　experiments　and　to　realize　theoretical　expectations.　Based　on　the　mesoscale　numerical　test　method,　the　established　intergranular　failure　mode-based　three-dimensional　meso-fracture　theoretical　analysis　model　of　concrete　is　modified.　The　adopted　numerical　model　of　concrete　is　composed　of　mortar,　interfaces　and　aggregates,　which　is　consistent　with　the　theoretical　model.　In　order　to　simulate　the　mechanical　behaviors　of　ordinary　strength　concrete,　the　plastic　damage　constitutive　model　is　used　to　characterize　the　mechanical　properties　of　mortar　and　interfaces,　and　aggregates　are　set　as　elastic　spheres.　A　self-designed　aggregate　placement　program　is　used　to　establish　standard　cubic　specimens　of　three-dimensional　model　concrete　with　cross-sectional　dimensions　of　100　mm　(1-graded),　150　mm　(2-graded),　300　mm　(3-graded)　and　450　mm　(4-graded).　The　theoretical　model　is　improved　by　the　splitting　tensile　loading　numerical　tests　of　standard　cubic　specimens　under　different　interfacial　strength　conditions.　A　semi-theoretical　and　semi-empirical　modified　calculation　formula　for　predicting　the　splitting　tensile　strength　of　different　graded　concrete　is　established.　Compared　with　the　results　of　numerical　and　physical　tests,　the　modified　theoretical　model　can　effectively　represent　the　variation　of　the　macroscopic　mechanical　properties　of　concrete　with　the　mechanical　and　structural　properties　of　meso-component　materials.　The　proposed　theoretical　model　modification　method　based　on　overlapping　effect　analysis　and　structural　effect　analysis　can　lay　a　foundation　for　the　subsequent　establishment　of　semi-theoretical　and　semi-empirical　prediction　formula　of　concrete　mechanical　properties　upon　modified　fracture　analysis　model.　©　2024　Tsinghua　University.　All　rights　reserved.