Fourteen　geometrically-similar　interior　reinforced　concrete　(RC)　beam-to-column　connections　whose　maximum　structural　sizes　were　700　mm×700　mm　were　designed.　The　seismic　performances　of　these　RC　beam-to-column　connections　subjected　to　monotonic　and　low-cycle　loading　were　tested.　The　effects　of　loading　type,　structural　size　and　stirrup　ratio　on　the　shear　failure　behavior　at　the　core　region　of　the　connections　were　studied.　Moreover,　the　size　effect　on　the　nominal　shear　strength　of　the　core　region　of　RC　connections　was　examined,　and　the　sources　of　size　effect　were　also　discussed.　The　test　results　and　analyses　indicate　that:　(1)　all　the　RC　beam-tocolumn　connections　under　monotonic　and　low-cycle　loading　failed　by　shear;　(2)　due　to　the　existence　of　low-cycle　fatigue　damage　characteristics,　the　nominal　shear　strength　of　the　joints　under　cyclic　loading　is　lower,　and　the　deformation　capacity　is　weaker;　(3)　the　nominal　shear　strength　decreases　with　the　increase　of　the　structural　size　of　RC　connections,　and　size　effect　phenomenon　is　obvious;　(4)　with　the　increase　of　stirrups　ratio,　the　shear　bearing　capacity　and　deformation　capacity　of　RC　connections　increases,　at　the　same　time　the　size　effect　in　shear　strength　is　weakened.　In　this　experiment,　the　dominant　effect　of　concrete　failure　and　the　low-cycle　fatigue　characteristic　of　loading　are　the　main　reasons　for　the　size　effect　of　shear　failure.　©　2019,　Science　Press.　All　right　reserved.