Thisstudyistoinvestigatethebehaviorof steeltiberreinfomedhigh-strengthmomwsubjected to highstrain-ratesandtiaxial sks.ses.ThevolumeIiactionof steeltibers(mngingfromOto 4’%o), tie confiningpessure (rangingii-emOto 70 N/inm2)and the loadingmte(rangingfrom 12x1(Y5to 2.0x10°lkc by strainrate)were chosenas testpammetem.One hundnxleighty cylindricalspecimens(50x100mm),inwhichthemortarmatrixhad a compressivesimmgthof about 140N/mm2,weretested.FromtestEM@ the efkcts of theseparameterson the t%lure modeandthemaximumstrengthofsteelfibernAntii high-shmgthmortarwereexamined FurtherrnoIE, M dynamict%ihnecriteriontbr steel fiberminfimed high-s!mmgth mortarwas PIU@ to prdkt tk maximumskngth under trkmialmpid impressive loadings.W criterionwasderivedfi-omthe dynamiccriterionfm high-stragth plainmortarby considering theadditionalconfiningpnxmredueto steelfibers.