The　dynamic　mechanical　behavior　of　concrete　has　an　obvious　strain-rate　dependency.　However,　the　current　knowledge　on　the　enhancement　of　dynamic　mechanical　properties　of　concrete　is　not　well　established　at　present.　Based　on　the　random　aggregate　structure　of　concrete,　the　mesh　grid　was　divided　by　the　characteristic　element　size　of　concrete.　The　equivalent　constitutive　relationship　for　concrete　meso-elements　was　derived　combining　the　strain-rate　effect　of　material　strength,　and　a　three-dimensional　meso-element　equivalent　model　of　heterogeneous　concrete　was　developed.　The　dynamic　compressive　tests　conducted　by　Dilger　et　al　were　simulated　using　a　two-dimensional　model.　Results　from　the　present　meso-element　equivalent　method　(MEEM)　showed　favorable　agreement　with　experimental　observations　and　the　results　from　the　random　aggregate　model,　illustrating　the　accuracy　of　the　present　meso-mechanical　approach.　Under　different　loading　rates,　the　dynamic　failure　patterns　and　the　macroscopic　mechanical　properties　of　the　three-dimensional　concrete　specimen　subjected　to　uniaxial　tension　and　compression　were　investigated　subsequently.　It　is　found　that,　as　loading　rate　increases　the　number　of　cracks　or　the　damaged　region　increases,　implying　that　the　fracture　process　at　high　rates　requires　more　energy　demand　to　reach　failure,　which　is　the　major　reason　for　the　enhancement　of　concrete　dynamic　strength.　©,　2015,　Tsinghua　University.　All　right　reserved.