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Finalexampaperforundergraduatesoftongjiuniversity(A)
Academicyearof2006~2007

SignatureofLecturer:			Authorizedby:
Course:Basicprinciplesofsteelstructures		Course#:03112609
Major:CivilEngineering			Class:
Name:StudentNo.:
Score:

Notethatfiguresareusuallynotdrawntoscaleandalldimensionsareinmillimetre.
P1.Answerthefollowingquestions:(30points)
Q:Inacurtailedinspectiontoabatchofstructuralsteel,threesamplesareselectedandtheiryieldpointsare340MPa,380MPaand390MPa,respectively.Whatistheactualyieldpointofthisbatchofstructuralsteel?Whichsteelgrade(Q235,Q345,orQ390)shouldthisstructuralsteelbeclassifiedaccordingtothenationalstandard?(4points)
A:345MPa[2points];steelgradeQ345[2point]

Q:Earthquakeactionisatypeofrepeatedloading,butinseismicdesignforasteelstructurefatiguecalculationbasedonstress-range-methodisrarelyused.Pleasestatethereason.(4points)
A:numberofstresscyclesaredifferentbetweenseismicdesignandfatigue.Earthquakeactionislow-cyclerepeatedload.[4point]

Q:Inthedesignofsectioncapacityforbendingmembers,memberssubjectedtocombinedbendingmomentandaxialforce,threedesigncriteriacanbeadopted:yieldonlyatextremefibre,fullyieldoftheentiresectionandpartialofthesectionyield.(a)whatisthecriteriaofpartialofthesectionyield?(b)whatistheadvantageofusingthispartiallyyieldcriteria?(c)underwhatloadconditionsitisnotappropriatetousethispartiallyyieldcriteria?(5points)
A:(a)theplasticity(bynormalstress)inflangeandwebispartiallydevelopedunderthebendingmoment[2points]
(b)savematerialusedbycompletelyutilizethehighstrengthofsteel[1points]
(c)underdynamicload,fatigue,orlargewidth-to-thicknessratioofcompressiveflange.[2points]

Q:WhenanI-shapedsteelgirderissubjectedtoaconcentratedload(forexample,transferredfromasecondarybeamorsupports),thelocalstressduetothetransverseforceshouldbechecked.Ifitisnotsatisfied,thefollowingmeasures/detailscouldbeused:(a)increasetheflangethicknessofthegirder;(b)increasetheflangewidthofthegirder;(c)increasethewebthicknessofthegirder;(d)increasethewebheightofthegirder;(e)a