In　flat　plate　structures,　interior　slab-column　joints　are　subjected　to　in-plane　restraints　and　bending-shear　actions,　which　can　significantly　impact　their　mechanical　performance　to　resist　progressive　collapse.　However,　research　in　this　area　is　still　lacking.　This　paper　presents　experimental　and　numerical　studies　of　pre-and　post-punching　performances　of　eccentrically　loaded　slab-column　joints　with　in-plane　restraints.　Quasi-static　tests　were　conducted　on　seven　joint　specimens,　including　one　concentrically　loaded　(CL)　joint　and　six　eccentrically　loaded　(EL)　ones.　The　effects　of　critical　structural　parameters　(i.e.,　eccentricity,　slab　thickness　and　reinforcement　ratio)　on　the　pre-and　post-punching　performances　were　investigated　by　analysing　the　load-displacement　relationships,　failure　modes　and　material　strains.　The　experimental　results　indicated　that　larger　eccentricity　could　lead　to　more　reduction　of　the　peak　punching　shear　capacity　by　as　much　as　62%,　whereas　it　has　little　effect　on　the　post　punching　capacity.　In　addition,　the　strain　results　of　the　through-column　rebars　showed　that,　with　the　well　restrained　boundary　conditions,　the　slab　flexural　reinforcement　(FR)　was　found　to　resist　the　applied　load　to　a　large　extent　at　small　deformations　and　still　able　to　contribute　greatly　during　the　post-punching　stage.　Numerical　analysis　was　conducted　to　gain　an　in-depth　understanding　toward　the　effects　of　varied　levels　of　in-plane　restraints　on　both　slab-column　joints　and　actual　flat　plate　structures.　It　was　found　that　the　lateral　stiffnesses　in　the　CL　joint　model　with　boundary　beams　and　the　substructure　model　were　similar,　which　was　around　400　N/mm.　Finally,　the　interactions　between　the　unbalanced　moment　and　shear　force　were　explored　and　compared　with　code　predictions　(ACI318-19　and　EC2-04).　Without　considering　the　enhancement　effects　from　in-plane　restraints,　the　codes　produced　over-conservative　predictions.　Based　on　the　FE　analyses,　the　correlation　between　the　dimensionless　ratio　e/d　(eccentricity/effective　thickness　of　slab)　and　punching　shear　strength　was　simplified　by　a　combined　straight　line　and　a　power　curve.