Anewretrofittingmethodisproposedhereinforreinforcedconcrete(RC)structuresthroughattachmentofanexternalstructure.Theexternalstructureconsistsofafiberconcreteencasedsteelframe,connectionslabandtransversebeams.Theexternalstructureisconnectedtotheexistingstructurethroughaconnectionslabandtransversebeams.Pseudostaticexperimentswerecarriedoutononeunretrofittedspecimenandthreeretrofittedframespecimens.Thecharacteristics,includingfailuremode,crackpattern,hysteresisloopsbehavior,relationshipofstrainanddisplacementoftheconcreteslab,aredemonstrated.Theresultsshowthattheloadcarryingcapacityisobviouslyincreased,andtheextensionlengthoftheslabandthenumberofcolumnswithintheexternalframeareimportantinfluencefactorsontheworkingperformanceoftheexistingstructure.Inaddition,thedisplacementdifferencebetweentheexistingstructureandtheouterstructurewascausedmainlybythreefactors:sheardeformationoftheslab,extractionoftransversebeams,anddriftoftheconjunctionpartbetweentheslabandtheexistingframe.Furthermore,thetotaldeformationdeterminedbythefirsttwofactorsaccountedforapproximately80%ofthedamage,thereforethesefactorsshouldbecarefullyconsideredinengineeringpracticetoenhancetheeffectsofthisnewretrofittingmethod.
