土木工程专业英语 教学课件 作者 陈瑛 6.5.Ductile Design of Concrete Frame Structures.ppt

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1、6.5DuctileDesignofConcreteFrameStructuresDuctilityDesignPhilosophyAreinforcedconcretestructurewithsufficientductilitycantakecareofoverloading,loadreversals,impactandsecondarystressesduetodifferentialsettlementoffoundation.givetheoccupantsufficienttimetovacatethestructur

2、ebyshowinglargedeformationbeforeitsfinalcollapse.becapableofresistingforcesanddeformationsattheyieldingofsteelreinforcement.DuctilityDesignPhilosophyToachieveanappropriatedegreeofductilityBrittlefailuremodesshouldbesuppressedBeamsshouldfailbeforecolumnsThestructuralduct

3、ilityisachievedintheformofinelasticrotationsinreinforcedconcretemembers.TheinelasticrotationsspreadoverdefiniteregionscalledasplastichingesDuctilityDesignPhilosophyPlastichingesforminbeamsratherthanincolumns:strong-column-weak-beam强柱弱梁behaviorPlastichingesformincolumns:

4、columnyieldingorstoreymechanism.Thiscolumntobeamflexuralstrengthratioisanimportantparametertoensurethatpossiblehingingoccursinbeamsratherthanincolumns.DuctilityDesignPhilosophysumofmomentsatjointfacescorrespondingtodesignflexuralstrengthofcolumnsframingintojointsumofmom

5、entsatjointfacescorrespondingtodesignflexuralstrengthofbeamsframingintojointDuctilityDesignPhilosophycolumntobeamflexuralstrengthratio,takenas1.4forGrade1,takenas1.2forGrade2,andtakenas1.1forGrade3.ThesumofmomentcapacityofthelowerendofcolumnatthefirststoreyofGrade1,2and

6、3shallbemultipliedbyanamplifyingfactorof1.5,1.25and1.15.DuctilityDetailingFrameBeamsClearspan-to-effectivedepthratio≥4ensurethatflexuralratherthanshearstrengthdominatesmemberbehaviorunderinelasticloadreversalsWidth-to-depthratio≥0.25provideadequateconfinementfortheconcr

7、eteWebwidth≥200mmprovideadequatemomenttransferbetweenbeamsandcolumns.DuctilityDetailing--FrameBeamsFrameBeamsbothtopandbottomminimumflexuralsteelisrequired.Theminimumtensionreinforcementratio-Table6.6.1,thepositivetonegativemomentresistanceratio≥0.5forframesassignedtoGr

8、ade1≥0.3forframesassignedGrade2orGrade3≥thecalculatednecessaryratio.negative/positivemomentresistanceatanysect