《材料員》課件-1-5建筑鋼材的標準與選用

建筑鋼材的標準與選用StandardsandselectionofconstructionsteelCONTENTS鋼筋混凝土結構用鋼Steelforreinforcedconcretestructures02鋼結構用鋼Steelforstructuralsteel0301建筑鋼材的主要鋼種Themainsteelgradesforconstructionsteel建筑鋼材的選用原則Principlesfortheselectionofconstructionsteel0401PART.01建筑鋼材的主要鋼種Themainsteelgradesforconstructionsteel建筑鋼材可分為鋼結構用鋼和鋼筋混凝土結構用鋼兩大類。Constructionsteelcanbedividedintotwomaincategories:steelfor鋼結構用鋼：型鋼、鋼板Steelforsteelstructure:profilesteel,steelplate鋼筋混凝土結構用鋼：鋼筋、鋼絲、鋼絞線Steelforreinforcedconcretestructures:steelbars,steelwires,steelstrands工程中常用鋼種主要有碳素結構鋼和合金鋼兩大類，其中合金鋼中使用較多的是普通低合金高強度結構鋼。Thecommonlyusedsteeltypesinengineeringmainlyincludecarbonstructuralsteelandalloysteel,amongwhichordinarylowalloyhigh-strengthstructuralsteelismorecommonlyusedinalloysteel.工程中常用鋼種主要有碳素結構鋼和合金鋼兩大類，其中合金鋼中使用較多的是普通低合金高強度結構鋼。Thecommonlyusedsteeltypesinengineeringmainlyincludecarbonstructuralsteelandalloysteel,amongwhichordinarylowalloyhigh-strengthstructuralsteelismorecommonlyusedinalloysteel.（1）碳素結構鋼

Carbonstructuralsteel（2）低合金高強度結構鋼

Lowalloyhighstrengthstructuralsteel其中，以“Q”代表屈服強度；屈服強度數(shù)值共分195MPa、215MPa、235MPa和275MPa四種；質量等級以硫、磷等雜質含量由多到少，分別由A、B、C，D符號表示；脫氧方法以F代表沸騰鋼、b表示半鎮(zhèn)靜鋼、Z和TZ分別表示鎮(zhèn)靜鋼和特殊鎮(zhèn)靜鋼。碳素結構鋼的牌號組成中，表示鎮(zhèn)靜鋼的“Z”和表示特殊鎮(zhèn)靜鋼的“TZ”可以省略。Amongthem,'Q'representstheyieldstrength;Theyieldstrengthvaluesaredividedintofourtypes:195MPa,215MPa,235MPa,and275MPa;ThequalitygradeisindicatedbythesymbolsA,B,CandD,respectively,withthecontentofsulfur,phosphorusandotherimpuritiesfrommoretoless;ThedeoxygenationmethodisrepresentedbyFforboilingsteel,bforsemikilledsteel,ZandTZforkilledsteelandspecialkilledsteel,respectively.Inthecompositionofcarbonstructuralsteelgrades,the"Z"representingkilledsteelandthe"TZ"representingspecialkilledsteelcanbeomitted.GB/T700-2006《碳素結構鋼》規(guī)定，鋼的牌號由代表屈服強度的字母、屈服強度數(shù)值、質量等級符號、脫氧方法符號四個部分按順序組成。GB/T700-2006"CarbonStructuralSteels"stipulatesthatthesteelgradeiscomposedoffourpartsinsequence:lettersrepresentingyieldstrength,yieldstrengthvalues,qualitygradesymbols,anddeoxygenationmethodsymbols.1）碳素結構鋼的牌號及其表示方法GradesandRepresentationMethodsofCarbonStructuralSteel

例如，Q235-A.F表示屈服點為235MPa的A級沸騰鋼；Q215-B表示屈服點為215MPa的B級鎮(zhèn)靜鋼。Forexample,Q235-AFrepresentsA-gradeboilingsteelwithayieldpointof235MPa;Q215-BrepresentsB-gradekilledsteelwithayieldpointof215MPa.2）碳素結構鋼的性能及選用PropertiesandSelectionofCarbonStructuralSteel

鋼材的選用一方面要根據(jù)鋼材的質量、性能及相應的標準，另一方面要根據(jù)工程使用條件對鋼材性能的要求。

Thechoiceofsteelshouldbebasedonthequality,performanceandcorrespondingstandardsofsteelontheonehand,andontheotherhandontherequirementsofsteelperformanceaccordingtotheconditionsofuseoftheproject.①Q195號、Q215號鋼強度低，但具有較好的塑性和韌性，冷彎性能較好，易于冷彎加工，常用作鋼釘、鉚釘、螺栓及鐵絲等。Q215號鋼經冷加工后可代替Q235號鋼使用。Q195andQ215steelshavelowstrengthbutgoodplasticityandtoughness,goodcoldbendingperformance,andareeasytocoldbend.Theyarecommonlyusedassteelnails,rivets,bolts,andironwires.Q215steelcanbeusedinsteadofQ235steelaftercoldprocessing.①Q195號、Q215號鋼強度低，但具有較好的塑性和韌性，冷彎性能較好，易于冷彎加工，常用作鋼釘、鉚釘、螺栓及鐵絲等。Q215號鋼經冷加工后可代替Q235號鋼使用。Q195andQ215steelshavelowstrengthbutgoodplasticityandtoughness,goodcoldbendingperformance,andareeasytocoldbend.Theyarecommonlyusedassteelnails,rivets,bolts,andironwires.Q215steelcanbeusedinsteadofQ235steelaftercoldprocessing.②Q235號鋼既具有較高的強度，又具有較好的塑性和韌性，可焊性也較好，且經焊接和氣割后力學性能亦仍穩(wěn)定，有利于冷加工，故廣泛地用于橋梁構件及鋼筋混凝土結構中的鋼筋等，是目前應用最廣泛的鋼種。Q235steelhashighstrength,goodplasticityandtoughness,goodweldability,andstablemechanicalpropertiesafterweldingandgascutting,whichisconducivetocoldprocessing.Therefore,itiswidelyusedinbridgecomponentsandsteelbarsinreinforcedconcretestructures,andiscurrentlythemostwidelyusedsteeltype.③Q255號、Q275號鋼強度較高，硬而脆，塑性、韌性和可焊性較差，不易焊接和冷加工，適于制作耐磨構件、機械零件和工具。也可以用于鋼結構構件。Q255andQ275steelshavehighstrength,hardnessandbrittleness,poorplasticity,toughnessandweldability,arenoteasytoweldandcoldwork,andaresuitableformakingwear-resistantcomponents,Machineelementandtools.Itcanalsobeusedforsteelstructuralcomponents.（2）低合金高強度結構鋼Lowalloyhighstrengthstructuralsteel

是一種在碳素鋼的基礎上添加總量小于5%的一種或多種合金元素的鋼材。具有強度高、塑性和低溫沖擊韌性好、耐腐蝕性好等特點。所加入合金元素主要有錳、硅、鋇、鈦、鉻、鎳等及稀土元素等。Itisatypeofsteelwithatotalamountoflessthan5%ofoneormorealloyingelementsaddedtocarbonsteel.Ithasthecharacteristicsofhighstrength,goodplasticityandlow-temperatureimpacttoughness,andgoodcorrosionresistance.Themainalloyingelementsaddedincludemanganese,silicon,barium,titanium,chromium,nickel,andrareearthelements.1)低合金高強度結構鋼的牌號及其表示方法GradesandRepresentationMethodsofLowAlloyHighStrengthStructuralSteel國標《低合金高強度結構鋼》(GB/T1591-1994)規(guī)定，低合金高強度結構鋼共有五個牌號：Q295、Q345、Q390、Q420和Q460。其牌號的表示方法是由屈服點字母Q、屈服點數(shù)值、質量等級(分A、B、C、D，E五級)三個部分組成。Accordingtothenationalstandard"LowAlloyHighStrengthStructuralSteel"(GB/T1591-1994),therearefivegradesoflowalloyhighstrengthstructuralsteel:Q295,Q345,Q390,Q420,andQ460.Therepresentationmethodofitsbrandnameiscomposedofthreeparts:theyieldpointletterQ,theyieldpointvalue,andthequalitylevel(dividedintofivelevels:A,B,C,D,andE).2）低合金高強度結構鋼的性能及應用PerformanceandApplicationofLowAlloyHighStrengthStructuralSteel

鋼材的選用一方面要根據(jù)鋼材的質量、性能及相應的標準，另一方面要根據(jù)工程使用條件對鋼材性能的要求。Theselectionofsteelshouldbebasedonthequality,performance,andcorrespondingstandardsofthesteel,aswellastherequirementsfortheperformanceofthesteelaccordingtotheengineeringusageconditions.

低合金高強度鋼的含碳量一般都較低，以便于鋼材的加工和焊接要求。其強度的提高主要是靠加入的合金元素結晶強化和固溶強化來達到。采用低合金高強度鋼的主要目的是減輕結構質量，延長使用壽命。這類鋼具有較高的屈服點和抗拉強度、良好的可焊性、塑性和沖擊韌性，具有耐銹蝕、耐磨、耐低溫性能，綜合性能好。所以在相同的使用條件下，可比碳素結構鋼節(jié)省用鋼20%～30%，對減輕結構自重有利。Thecarboncontentoflowalloyhigh-strengthsteelisgenerallylowtofacilitatetheprocessingandweldingrequirementsofthesteel.TheincreaseofitsstrengthismainlyachievedbytheadditionofalloyingelementsforcrystallizationstrengtheningandSolidsolutionstrengthening.Themainpurposeofusinglowalloyhigh-strengthsteelistoreducestructuralmassandextendservicelife.Thistypeofsteelhashighyieldpointandtensilestrength,goodweldability,plasticity,andimpacttoughness,aswellascorrosionresistance,wearresistance,lowtemperatureresistance,andgoodoverallperformance.Sounderthesameusageconditions,itcansave20%to30%ofsteelcomparedtocarbonstructuralsteel,whichisbeneficialforreducingtheselfweightofthestructure.低合金高強度結構鋼主要用于軋制各種型鋼、鋼板、鋼管及鋼筋，廣泛用于結構鋼和鋼筋混凝土結構中，特別適用于各種重型結構、高層結構、大跨度結構及橋梁工程等。Lowalloyhigh-strengthstructuralsteelismainlyusedforrollingvarioustypesofsteel,steelplates,steelpipes,andsteelbars.Itiswidelyusedinstructuralsteelandreinforcedconcretestructures,especiallysuitableforvariousheavy-dutystructures,high-risestructures,large-spanstructures,andbridgeengineering.02PART.02鋼筋混凝土結構用鋼Steelforreinforcedconcretestructures工程中常用的鋼筋混凝土結構用鋼，主要由碳素結構鋼和低合金結構鋼軋制而成，根據(jù)生產工藝、性能和用途的不同，主要有熱軋鋼筋、冷加工鋼筋（冷拉熱軋鋼筋、冷軋帶肋鋼筋）、熱處理鋼筋、冷拔低碳鋼絲、預應力混凝土用鋼絲和鋼絞線等，按直條或盤條（也稱盤圓）供貨。直徑為5mm以上的稱為鋼筋，直徑為5m及5mm以下的稱為鋼絲。Thecommonlyusedsteelforreinforcedconcretestructuresinengineeringismainlyrolledfromcarbonstructuralsteelandlowalloystructuralsteel.Accordingtodifferentproductionprocesses,properties,anduses,therearemainlyhot-rolledsteelbars,cold-workedsteelbars(cold-drawnhot-rolledsteelbars,cold-rolledribbedsteelbars),heat-treatedsteelbars,cold-drawnlow-carbonsteelwires,prestressedconcretesteelwires,andsteelstrands,whicharesuppliedinstraightorwirerods(alsoknownascoils).Steelbarswithadiameterofover5mmarecalledsteelbars,whilesteelwireswithadiameterof5mandbelowarecalledsteelwires.（1）熱軋鋼筋

Hotrolledsteelbars經過熱軋成型并自然冷卻的成品鋼筋。Finishedsteelbarsformedbyhotrollingandnaturallycooled.1）熱軋光圓鋼筋Hotrolledplainroundsteelbars（1）熱軋鋼筋

Hotrolledsteelbars經過熱軋成型并自然冷卻的成品鋼筋。Finishedsteelbarsformedbyhotrollingandnaturallycooled.國標《鋼筋混凝土用熱軋光圓鋼筋》規(guī)定，熱軋光圓鋼筋級別為I級，強度等級代號為HPB235，“235”表示屈服強度要求值（MPa）。Accordingtothenationalstandard"Hotrolledplainroundsteelbarsforreinforcedconcrete",thegradeofhotrolledplainroundsteelbarsisGradeI,withthestrengthgradecodeHPB235,and"235"representstherequiredyieldstrengthvalue(MPa).1）熱軋光圓鋼筋Hotrolledplainroundsteelbars光圓鋼筋是用Q235或Q235碳素結構鋼軋制而成的鋼筋，其強度較低，但具有塑性好、伸長率高、便于彎曲成型和進行各種冷加工、容易焊接等特點，廣泛用于普通鋼筋混凝土構件中，作為中小型鋼筋混凝土結構的主要受力鋼筋、構造筋和各種鋼筋混凝土結構的箍筋等。PlainroundsteelbarsaresteelbarsrolledfromQ235orQ235carbonstructuralsteel,whichhavelowstrengthbutgoodplasticity,highelongation,easybendingandforming,variouscoldprocessing,andeasywelding.Theyarewidelyusedinordinaryreinforcedconcretecomponents,asthemainload-bearingsteelbars,structuralsteelbars,andstirrupsofvariousreinforcedconcretestructureswithsmallandmedium-sizedsteelbars.2）熱軋帶肋鋼筋

Hotrolledribbedsteelbars熱軋帶肋鋼筋是采用低合金鋼熱軋而成，橫截面通常為圓形，表面有兩條縱肋，并沿長度方向均勻分布。其含碳量為0.1%～0.25%。帶肋鋼筋有月牙肋鋼筋和等高肋鋼筋等，如圖所示。Hotrolledribbedsteelbarsarehot-rolledfromlowalloysteel,withacircularcross-sectionandtwolongitudinalribsonthesurface,evenlydistributedalongthelengthdirection.Itscarboncontentrangesfrom0.1%to0.25%.Ribbedsteelbarsincludecrescentribbedsteelbarsandequalheightribbedsteelbars,asshowninthefigure.（a）月牙肋鋼筋（b）等高肋鋼筋(a)Crescentribbedbars（b）Equalheightribbedsteelbars國標《鋼筋混凝土用熱軋帶肋鋼筋》規(guī)定，熱軋帶肋鋼筋分為HRB335、HRB400、HRB500三個牌號。HRB335，HRB400是采用普通質量低合金鎮(zhèn)靜鋼軋制而成的，鋼筋的強度較高，塑性和焊接性能較好，廣泛用于大中型鋼筋混凝土結構的受力筋；HRB500是采用優(yōu)質低合金鎮(zhèn)靜鋼軋制而成的，鋼筋強度高，但塑性和焊接性能較差，可用作預應力鋼筋。Accordingtothenationalstandard"Hotrolledribbedsteelbarsforreinforcedconcrete",hotrolledribbedsteelbarsaredividedintothreegrades:HRB335,HRB400,andHRB500.HRB335andHRB400arerolledfromordinaryqualitylowalloykilledsteel.Thesteelbarshavehighstrength,goodplasticityandweldingperformance,andarewidelyusedforload-bearingbarsinlargeandmedium-sizedreinforcedconcretestructures;HRB500isrolledfromhigh-qualitylowalloykilledsteel,withhighstrengthbutpoorplasticityandweldingperformance.Itcanbeusedasprestressedsteelbars.熱軋帶肋鋼筋因表面帶肋，加強了鋼筋與混凝土之間的粘結力，廣泛用于大、中型鋼筋混凝土結構的受力鋼筋，經過冷拉后可用作預應力鋼筋。Hotrolledribbedsteelbars,duetotheirsurfaceribs,enhancethebondingforcebetweenthesteelbarsandconcrete,andarewidelyusedasload-bearingsteelbarsinlargeandmedium-sizedreinforcedconcretestructures.Aftercolddrawing,theycanbeusedasprestressedsteelbars.（2）冷拉熱軋鋼筋

Colddrawnandhot-rolledsteelbars冷拉可使屈服點提高20%～30%，材料變脆、屈服階段縮短，伸長率降低，冷拉時效后強度提高。實際操作中可將冷拉、除銹、調直、切斷合并為一道工序，這樣簡化了流程，提高了效率。冷拉既可以節(jié)約鋼材，又可以制作預應力鋼筋，是鋼筋加工的常用方法之一。Colddrawingcanincreasetheyieldpointby20%to30%,makethematerialbrittle,shortentheyieldstage,reduceelongation,andincreasestrengthaftercolddrawingaging.Inpracticaloperation,colddrawing,rustremoval,straightening,andcuttingcanbecombinedintooneprocess,whichsimplifiestheprocessandimprovesefficiency.Colddrawingcannotonlysavesteelbutalsoproduceprestressedsteelbars,whichisoneofthecommonlyusedmethodsforsteelbarprocessing.(3)冷軋帶肋鋼筋

Coldrolledribbedsteelbars冷軋帶肋鋼筋采用熱軋圓盤條經冷軋而成，表面帶有沿長度方向均勻分布的三面或兩面的月牙肋。國標《冷軋帶肋鋼筋》(GB13780-2008)規(guī)定，冷軋帶肋鋼筋有CRB550、CRB650、CRB800、CRB970、CRB1170五個牌號。Coldrolledribbedsteelbarsaremadeofhot-rolledcircularstripsthroughcoldrolling,withthreeortwocrescentribsevenlydistributedalongthelengthdirectiononthesurface.Accordingtothenationalstandard"Coldrolledribbedsteelbars"(GB13780-2008),therearefivegradesofcoldrolledribbedsteelbars:CRB550,CRB650,CRB800,CRB970,andCRB1170.（4）冷拔低碳鋼絲

Colddrawnlow-carbonsteelwire

冷拔低碳鋼絲是用直徑6～8mm的碳素結構鋼Q235或Q215熱軋圓盤條經冷拔而成。通過多次強力拔制而得到直徑為3mm、4mm、5mm的鋼絲。其屈服強度可提高40%～60%，同時塑性降低。因此冷拔低碳鋼絲失去了低碳鋼的性能，變得硬脆，屬硬鋼類鋼絲。冷拔低合金鋼絲的抗拉強度比冷拔低碳鋼絲更高，可用于中、小型混凝土構件中的預應力筋。Colddrawnlow-carbonsteelwireismadefromhot-rolledcircularstripsofcarbonstructuralsteelQ235orQ215withadiameterof6-8mmthroughcolddrawing.Steelwireswithdiametersof3mm,4mm,and5mmwereobtainedthroughmultiplestrongdrawingprocesses.Itsyieldstrengthcanbeincreasedby40%to60%,whileplasticitydecreases.Therefore,colddrawnlow-carbonsteelwirelosesthepropertiesoflow-carbonsteelandbecomeshardandbrittle,belongingtothecategoryofhardsteelwire.Thetensilestrengthofcolddrawnlowalloysteelwireishigherthanthatofcolddrawnlowcarbonsteelwire,anditcanbeusedforprestressedreinforcementinsmallandmedium-sizedconcretecomponents.（5）預應力混凝土用熱處理鋼筋

Heattreatedsteelbarsforprestressedconcrete

預應力混凝土用熱處理鋼筋是用熱軋帶肋鋼筋（即普通熱軋中碳低合金鋼筋）經淬火、回火等調質處理制成的螺紋鋼筋。通常有直徑為6mm、8.2mm，10mm三種規(guī)格。鋼筋經熱處理后應卷成盤，每盤應由一整根鋼筋盤成，且每盤鋼筋的重量應不小于60kg。Heattreatedsteelbarsforprestressedconcretearethreadedsteelbarsmadefromhot-rolledribbedsteelbars(i.e.ordinaryhot-rolledmediumcarbonlowalloysteelbars)afterquenching,tempering,andotherquenchingandtemperingtreatments.Thereareusuallythreesizeswithdiametersof6mm,8.2mm,and10mm.Afterheattreatment,thesteelbarsshouldberolledintocoils,andeachcoilshouldbemadeofacompletesteelbar,andtheweightofeachcoilofsteelbarsshouldnotbelessthan60kg.熱處理鋼筋具有較高的綜合力學性能，除具有很高的強度和穩(wěn)定的預應力值外，還具有高韌性和高握裹力等優(yōu)點，主要用于預應力混凝土橋梁軌枕，還用于預應力梁、板結構及吊車梁等。鋼筋成盤供應，開盤后能自行伸直，可省去冷拉，不需調直和焊接，施工方便，且節(jié)約鋼材。但應防止產生銹蝕及刻痕等現(xiàn)象。Heattreatedsteelbarshavehighcomprehensivemechanicalproperties.Inadditiontohighstrengthandstablepre-stressvalue,theyalsohaveadvantagessuchashightoughnessandhighgrippingforce.Theyaremainlyusedforpre-stressedconcretebridgesleepers,aswellaspre-stressedbeams,platestructures,andcranebeams.Thesteelbarsaresuppliedincoils,whichcanbestraightenedbythemselvesafteropening,eliminatingtheneedforcolddrawing,straighteningandwelding,makingconstructionconvenientandsavingsteel.However,rustandscratchesshouldbepreventedfromoccurring.03PART.03鋼結構用鋼SteelforSteelStructures鋼結構用鋼主要應用型鋼、鋼板、鋼管等。Themainapplicationsofsteelforsteelstructuresaresectionsteel,steelplates,steelpipes,etc.（1）型鋼Sectionsteel在鋼結構用鋼中一般可直接選用各種規(guī)格與型號的型鋼。構件之間可直接連接或附加連接鋼板進行連接。連接方式有鉚接、螺栓連接或焊接。Insteelstructures,variousspecificationsandmodelsofsteelprofilescangenerallybedirectlyselected.Componentscanbedirectlyconnectedorattachedwithsteelplatesforconnection.Theconnectionmethodsincluderiveting,boltconnection,orwelding.我國建筑用熱軋型鋼主要采用碳素結構鋼和低合金鋼，其中應用最多的是碳素鋼Q235A，低合金鋼Q345（16Mn）及Q390（15MnV），碳素結構鋼Q235A制成的熱軋型鋼，強度適中、塑性和可焊性較好、冶煉容易、成本低，適用于土木工程中的各種鋼結構。低合金鋼制成的熱軋型鋼，強度高，可用于大跨度、承受動荷載的鋼結構工程。HotrolledsteelsectionsforconstructioninChinamainlyusecarbonstructuralsteelandlowalloysteel,amongwhichcarbonsteelQ235A,lowalloysteelQ345(16Mn)andQ390(15MnV)arethemostcommonlyused.HotrolledsteelsectionsmadeofcarbonstructuralsteelQ235Ahavemoderatestrength,goodplasticityandweldability,easysmeltingcapacity,andlowcost,andaresuitableforvarioussteelstructuresincivilengineering.HotrolledsectionsteelmadeoflowalloysteelhashighstrengthandcanbeusedinsteelStructuralengineeringwithlargespanandbearingdynamicload.（2）壓型鋼板

Profiledsteelplate壓型鋼板是由厚度為0.4～2mm的鋼板壓制而成。鋼板表面涂漆、鍍鋅、涂有機層（又稱彩色壓型鋼板），以防止銹蝕。其優(yōu)點是輕質、高強、耐久性好、美觀、施工快，常用作屋面板、墻板及樓板等。Profiledsteelplatesaremadebypressingsteelplateswithathicknessof0.4-2mm.Thesurfaceofthesteelplateispainted,galvanized,andcoatedwithanorganiclayer(alsoknownascoloredprofiledsteelplate)topreventcorrosion.Itsadvantagesarelightweight,high-strength,gooddurability,aesthetics,andfastconstruction,commonlyusedasroofpanels,wallpanels,andfloorslabs.（3）圓鋼和方鋼

Roundandsquaresteel

圓鋼的規(guī)格以“直徑”（mm）表示，規(guī)格范圍為5.5～250mm；方鋼的規(guī)格以“邊長”（mm）表示，規(guī)格范圍為5.5～200mm。圓鋼和方鋼在普通鋼結構中很少采用，可用于輕型鋼結構，用做一般桿件和連接件。Thespecificationofroundsteelisrepresentedby"diameter"(mm),withaspecificationrangeof5.5-250mm;Thespecificationofsquaresteelisexpressedin"sidelength"(mm),withaspecificationrangeof5.5-200mm.Roundsteelandsquaresteelarerarelyusedinordinarysteelstructuresandcanbeusedinlightweightsteelstructuresasgeneralmembersandconnectors.（4）鋼管

Steelpipe

鋼管的品種很多，按制造方法不同，鋼結構所用鋼管分為熱軋無縫鋼管和焊接鋼管兩大類。Therearemanytypesofsteelpipes,andaccordingtodifferentmanufacturingmethods,thesteelpipesusedinsteelstructuresaredividedintotwocategories:hot-rolledseamlesssteelpipesandweldedsteelpipes.1）無縫鋼管：熱軋無縫鋼管以優(yōu)質碳素鋼和低合金結構鋼為原材料，多采用熱軋－冷拔聯(lián)合工藝生產，也可用冷軋方式生產，但后者成本較高。無縫鋼管主要用于壓力管道和一些特定的鋼結構。1)Seamlesssteelpipe:Hotrolledseamlesssteelpipesaremadeofhigh-qualitycarbonsteelandlowalloystructuralsteelasrawmaterials,andareoftenproducedusingacombinedprocessofhotrollingandcolddrawing.Theycanalsobeproducedbycoldrolling,butthelatterhasahighercost.Seamlesssteelpipesaremainlyusedforpressurepipelinesandsomespecificsteelstructures.1）無縫鋼管：熱軋無縫鋼管以優(yōu)質碳素鋼和低合金結構鋼為原材料，多采用熱軋－冷拔聯(lián)合工藝生產，也可用冷軋方式生產，但后者成本較高。無縫鋼管主要用于壓力管道和一些特定的鋼結構。1)Seamlesssteelpipe:Hotrolledseamlesssteelpipesaremadeofhigh-qualitycarbonsteelandlowalloystructuralsteelasrawmaterials,andareoftenproducedusingacombinedprocessofhotrollingandcolddrawing.Theycanalsobeproducedbycoldrolling,butthelatterhasahighercost.Seamlesssteelpipesaremainlyusedforpressurepipelinesandsomespecificsteelstructures.2）焊接鋼管：采用優(yōu)質或普通碳素鋼鋼板卷焊而成，按其焊縫形式有直縫電焊鋼管和螺旋焊鋼管。價格較低，適用于各種結構、輸送管道等用途。焊接鋼管成本較低，容易加工，但多數(shù)情況下抗壓性能較差。2)Weldedsteelpipe:Itismadeofhigh-qualityorordinarycarbonsteelplaterolledandwelded,andtherearestraightseamelectricweldedsteelpipesandspiralweldedsteelpipesaccordingtotheirweldforms.Thepriceisrelativelylow,suitableforvariousstructures,transportationpipelines,andotherpurposes.Weldedsteelpipeshavelowercostsandareeasytoprocess,butinmostcases,theircompressiveperformanceispoor.

鋼管在相同截面積下，剛度較大，因而是中心受壓構件的理想截面；在建筑鋼結構上，鋼管多用于制作桁架、塔桅、鋼管混凝土等，廣泛應用于高層建筑、廠房柱、塔柱、壓力管道等工程中。Steelpipeshavehighstiffnessunderthesamecross-sectionalarea,makingthemanidealcross-sectionforcentralcompressionmembers;Intheconstructionofsteelstructures,steelpipesareoftenusedtomaketrusses,towermasts,steelpipeconcrete,andarewidelyusedinhigh-risebuildings,factorycolumns,towercolumns,pressurepipelines,andotherengineeringprojects.04PART.04建筑鋼材的選用原則Principlesforselectingbuildingsteel（1）荷載性質。對于經常承受動力或振動荷載的結構，容易產生應力集中，從而引起疲勞破壞，需要選用材質高的鋼材。(1)Loadproperties.Forstructuresthatfrequentlybeardynamicorvibrationloads,stressconcentrationcaneasilyoccur,leadingtofatiguefailure.Therefore,itisnecessarytochoosehighqualitysteelmaterials.（1）荷載性質。對于經常承受動力或振動荷載的結構，容易產生應力集中，從而引起疲勞破壞，需要選用材質高的鋼材。(1)Loadproperties.Forstructuresthatfrequentlybeardynamicorvibrationloads,stressconcentrationcaneasilyoccur,leadingtofatiguefailure.Therefore,itisnecessarytochoosehighqualitysteelmaterials.（2）使用溫度。對于經常處于低溫狀態(tài)的結構，鋼材容易發(fā)生冷脆斷裂，特別是焊接結構更甚，因而要求鋼材具有良好的塑性和低溫沖擊韌性。(2)Usetemperature.Forstructuresthatareofteninalow-temperaturestate,steelispronetocoldbrittlefracture,especiallyinweldedstructures,whichrequiressteeltohavegoodplasticityandlow-temperatureimpacttoughness.（3）連接方式。對于焊接結構，當溫度變化和受力性質改變時，焊縫附近的母體金屬容易出現(xiàn)冷、熱裂紋，促使結構早期破壞。所以焊接結構對鋼材化學成分和機械性能要求比較嚴格。(3)Connectionmethod.Forweldedstructures,whentemperatureandstresspropertieschange,theparentmetalneartheweldseamispronetocoldandhotcracks,promotingearlystructuralfailure.Sotheweldingstructurehasstrictrequirementsforthechemicalcompositionandmechanicalpropertiesofthesteel.（4）鋼材厚度。鋼材力學性能一般隨厚度增大而降低，鋼材經多次壓制后，鋼的內部結晶組織更為緊密，強度更高，質量更好。故一般結構用的鋼材厚度不宜超過40mm。(4)Steelthickness.Themechanicalpropertiesofsteelgenerallydecreasewithincreasingthickness.Aftermultiplepresses,theinternalcrystallinestructureofthesteelbecomestighter,withhigherstrengthandquality.Therefore,thethicknessofsteelusedforgeneralstructuresshouldnotexceed40mm.（3）連接方式。對于焊接結構，當溫度變化和受力性質改變時，焊縫附近的母體金屬容易出現(xiàn)冷、熱裂紋，促使結構早期破壞。所以焊接結構對鋼材化學成分和機械性能要求比較嚴格。(3)Connectionmethod.