Introduction:　The　sandwich　joints　casted　core　area　with　weaker　strength　concrete　of　beam,　has　more　advantages　than　the　traditional　joints　casted　core　area　with　higher　strength　concrete　of　column,　such　as　the　simple　construction　and　quality　assurance,　while　China　design　codes　are　too　simple　about　the　sandwich　joints　and　have　no　clear　calculation　methods.　Methods:　Due　to　the　scarcity　of　rational　models　for　predicting　the　strength　of　RC　beam-column　sandwich　joints,　a　modified　simplified　softened　strut-and-tie　model　suggests　a　more　rational　calculation　method　for　the　effective　compressive　strength　and　the　height　of　the　joint　concrete　based　on　the　simplified　softened　strut-and-tie.　The　shear　strength　of　existing　tested　15　sandwich　interior　joints　is　calculated　by　using　the　modified　simplified　softened　strut-and-tie　model.　Furthermore,　the　theory　results　are　compared　with　those　of　the　code　method　and　those　of　the　simplified　softened　strut-and-tie　model.　Results　and　Conclusion:　The　results　indicate　that　the　code　method　is　more　conservative,　and　the　modified　simplified　softened　strut-and-tie　can　more　precisely　predict　the　joint　shear　strength　than　that　of　the　softened　strut-and-tie　model　and　more　secure　than　that　of　the　code　method.　Thus,　the　modified　simplified　softened　strut-and-tie　model　can　reasonable　reveal　the　failure　mechanism　of　RC　beam-column　sandwich　interior　joints.　©　Hou　et　al.