第1页共6页编号:时间:2021年x月x日书山有路勤为径,学海无涯苦作舟页码:第1页共6页4.1INVESTIGATIONOFSTRUCTURALBEHAVIORInvestigatinghowstructuresbehaveisanimportantpartofstructuraldesign:itprovidesabasisforensuringtheadequacyandsafetyofadesign,InthissectionIdiscussstructuralinvestigationingeneral.AsIdothroughoutthisbook.Ifocusonmaterialrelevanttostructuraldesigntasks.PurposeofInvestigationMoststructuresexistbecausetheyareneeded.Anyevaluationofastructurethusmustbeginwithananalysisofhoweffectivelythestructuremeetstheusagerequirements.Designersmustconsiderthefollowingthreefactors:Functionality.orthegeneralphysicalrelationshipsofthestructure'sform.detail.durability.fireresistance.deformationresistance.andsoon.Feasibility.includingcost.availabilityofmaterialsandproducts.andpracticalityofconstruction.Safety.orcapacity10resistanticipatedloads.MeansAninvestigationofafullydefinedstructureinvolvesthefollowing:1.Determinethestructure'sphysicalbeing-materials,form,scale.orientation.location.supportconditions,andinternalcharacteranddetail.2.Determinethedemandsplacedonthestructure-thatis.loads.3.Determinethestructure'sdeformationlimits.4.Determinethestructure'sloadresponse-howithandlesinternalforcesandstressesandsignificantdeformations.5.Evaluatewhetherthestructurecansafelyhandletherequiredstructuraltasks.Investigationmaytakeseveralforms.YoucanVisualizegraphicallythestructure'sdeformationunderload.Manipulatemathematicalmodels.Testthestructureorascaledmodel,measuringitsresponsestoloads.Whenprecisequantitativeevaluationsarerequired.usemathematicalmodelsbasedonreliabletheoriesordirectlymeasurephysicalresponses.Ordinarily.第2页共6页第1页共6页编号:时间:2021年x月x日书山有路勤为径,学海无涯苦作舟页码:第2页共6页mathematicalmodelingprecedesanyactualconstruction-evenofatestmodel.Limitdirectmeasurementtoexperimentalstudiesortoverifyinguntestedtheoriesordesignmethods.VisualAidsInthisbook,Iemphasizegraphicalvisualization;sketchesarcinvaluablelearningandproblem-solvingaids.Threetypesofgraphicsaremostuseful:thefree-bodydiagram.theexaggeratedprofileofaload-deformedstructure.andthescaledpial.Afree-bodydiagramcombinesapictureofanisolatedphysicalclemenIwithrepresentationsofallexternalforces.Theisolatedclementmaybeawholestructureorsomepartofit.Forexample.Figure4.1ashowsanentirestructure-abeamand-eolumnrigidbent-andtheexternalforces(representedbyarrows).whichincludegravity.wind.andthereactiveresistanceofthesupports(calledthereactions).Note:Suchaforcesystemholdsthestructureinstaticequilibrium.Figure4.lbisafree-bodydiagramofasinglebeamfromthebent.Operatingonthebeamaretwoforces:itsownweightandtheinteractionbetweenthebeamendsandthecolumns10whichthebeamisallached.TheseinteractionsarenotvisibleintheIreebodydiagramofthewholebent.soonepurposeofthediagramforthebeamistoillustratetheseinteractions.Forexample.notethatthecolumnstransmittotheendsofthebeamshorizontalandverticalforcesaswellasrotationalbendingactions.Figure4.lcshowsanisolatedportionofthebeamlength.illustratingthebeam'sinternalforceactions.Operatingonthisfreebodyarcitsownweightandtheactionsofthebeamsegmentsontheoppositesidesoftheslicingplanes.sinceitistheseactionsthatholdtheremovedportioninplaceinthewholebeam.Figure4.ld.atinysegment.orparticle.ofthebeammaterialisisolated,illustratingtheinteractionsbetweenthisparticleandthoseadjacenttoit.Thisde...