PRINCIPLES OF STRUCTURAL DESIGN

0

PRINCIPLES OF STRUCTURAL DESIGNWai-Fah ChenEric M. Lui

Structuralsteelisaconstructionmaterialthatpossessesattributessuchasstrength,stiffness,toughness,andductilitythataredesirableinmodernconstructions.Strengthistheabilityofamaterialtoresiststress.Itismeasuredintermsofthematerial’syieldstrengthFyandultimateortensilestrengthFu.SteelusedinordinaryconstructionsnormallyhavevaluesofFyandFuthatrangefrom36to50ksi(248to345MPa)andfrom58to70ksi(400to483MPa),respectively,althoughhigher-strengthsteelsarebecomingmorecommon.Stiffnessistheabilityofamaterialtoresistdeformation.Itismeasuredinseveraluniaxialengineeringstress–


straincurvesobtainedfromcoupontestsforvariousgradesofsteelsareshown,itisseenthatthemodulusofelasticityEdoesnotvaryappreciablyforthedifferentsteelgrades.Therefore,avalueof29,000ksi(200GPa)isoftenusedfordesign.Toughnessistheabilityofamaterialtoabsorbenergybeforefailure.Itismeasuredastheareaunderthematerial’sstress–straincurve.AsshowninFigure1.1,most(especiallythelowergrade)steelspossesshightoughnessthatmadethemsuitableforbothstaticandseismicapplications.Ductilityistheabilityofamaterialtoundergolargeinelastic(orplastic)deformationbeforefailure.Itismeasuredintermsofpercentelongationorpercentreductioninareaofthespecimentestedinuniaxialtension.Forsteel,percentelongationrangesfromaround10to40fora2-in.(5-cm)gagelengthspecimen.Ductilitygenerallydecreaseswithincreasingsteelstrength.Ductilityisaveryimportantattributeofsteel.Theabilityofstructuralsteeltodeformconsiderablybeforefailurebyfractureallowsanindeterminatestructuretoundergostressredistribution.Ductilityalsoenhancestheenergyabsorptioncharacteristicofthestructure,whichisextremelyimportantinseismicdesign
Start Download




ليست هناك تعليقات:

إرسال تعليق

يتم التشغيل بواسطة Blogger.