The　premise　of　equivalent　linearization　method　is　that　the　peak　response　of　an　inelastic　system　can　be　estimated　as　the　peak　response　of　a　linear　elastic　system　having　reduced　stiffness　and　increased　damping.　Different　approaches　have　been　used　to　determine　the　properties　of　the　equivalent　linear　system,　in　particular　the　equivalent　damping　ratio.　In　general,　equivalent　damping　is　specified　as　the　sum　of　elastic　and　hysteretic　component,　where　the　former　is　assumed　to　be　constant,　and　the　latter　depends　on　the　ductility　and　hysteresis　model.　It　is　found　that,　however,　many　studies　only　focus　on　the　definition　of　hysteretic　damping　and　omit　the　influence　of　elastic　damping　on　the　prediction　accuracy　of　equivalent　linearization　method.　Motivated　by　this　limitation,　comprehensive　parametric　analysis　is　performed　in　this　paper　based　on　bilinear　hysteretic　SDOF　systems　to　identify　the　influence　of　elastic　damping.　Results　show　that　elastic　damping　has　significant　influence　on　the　estimation　accuracy　of　equivalent　linearization　method.　To　improve　the　estimation　accuracy　of　equivalent　linearization　method,　improved　method　of　equivalent　damping　is　proposed　by　considering　the　influence　of　elastic　damping.　It　is　found　that　the　proposed　method　is　able　to　provide　accurate　and　conservative　values　of　equivalent　damping　for　practical　design　of　base　isolation　systems.　©　2017