Steel-plate　composite　walls　comprise　a　steel　plate　encased　in　the　middle　of　a　reinforced　concrete　shear　wall　[referred　to　as　＂composite　plate　shear　walls-concrete　encased　(C-PSW/CE)＂],　or　a　concrete　infill　sandwiched　between　two　steel　faceplates　[referred　to　as　＂double-skin　composite　(DSC)　walls＂].　In　this　study,　two　I-shaped　C-PSW/CE　specimens　with　a　shear-to-span-ratio　of　1.2　were　experimentally　tested　to　investigate　the　cyclic　in-plane　shear　behavior　of　C-PSW/CE　used　for　high-rise　buildings.　Both　wall　specimens　were　identical　in　geometric　dimensions　and　reinforcement　details,　with　the　exception　of　axial　force　ratio.　The　results　indicated　that　shear　failure　occurred　in　the　two　wall　specimens　due　to　serious　spalling　of　web　concrete,　followed　by　buckling　of　the　embedded　steel　plate　and　vertically　distributed　reinforcements.　The　increase　in　axial　force　ratio　from　0.16　to　0.29　resulted　in　an　11.8%　rise　in　peak　strength　and　a　decrease　in　ultimate　shear　strain　of　27%　for　C-PSW/CE.　A　comparison　between　C-PSW/CE　and　DSC　walls　indicated　that　the　latter　had　a　similar　peak　strength　to　the　former,　but　clearly　improved　the　ultimate　drift.　This　is　because　the　double　faceplates　of　DSC　walls　provided　a　more　effective　restraint　to　the　infilled　concrete　and　prevented　spalling　of　concrete.　Then,　this　paper　developed　a　refined　numerical　model　to　simulate　C-PSW/CE　and　compared　the　analytical　results　with　the　experimental　data.　Finally,　shear　strength　design　formulas　specified　in　Chinese　and　US　codes　were　verified　against　a　large　volume　of　test　data　and　numerical　simulation　results.　The　shear　strength　of　C-PSW/CE　was　reasonably　estimated　by　the　JGJ　3-2010　design　formulas　(Chinese　code),　while　significantly　underestimated　by　the　AISC　341-16　formula　(US　code)　which　neglects　the　shear　contribution　of　reinforced　concrete　encasement.　©　2023　American　Society　of　Civil　Engineers.