第1、2章習(xí)題課(2學(xué)時)課件

——混凝土結(jié)構(gòu)原理(1-2章)第1、2章習(xí)題課(2學(xué)時)CHAPTER1INTRODUCTION(緒論)1.Problemsforponderation(思考題)1.1Explaintheeffectofthattheconcretebeamhassteelreinforcingbarsembeddedatthebottomunderloading.

（解釋在底部配有鋼筋的混凝土梁在荷載作用下的影響）

Aplainconcretebeamunderloadingwillbecrackedatthetensionregionofthemid-span(跨中)andthebeamwillfailsuddenlywhentheloadreachit’slimitvalue.Butreinforcingbarsembeddedatthebottomoftheconcretebeamcantakeupthetensionthereaftertheconcreteiscracked.whenthesteelapproachesyieldingstress,thecrackaresolargeofferingthewarning(預(yù)警)thatthebeamisgoingtofail.提高梁的承載能力和變形能力第1、2章習(xí)題課(2學(xué)時)

1.2Whycanworktogethertheconcreteandreinforcement?(鋼筋和混凝土為什么可以共同工作）

Concreteandreinforcecanworktogetherbecause:1)Thereisasufficientlystrongbondbetweenthetwomaterials.2)Thethermalexpansioncoefficients(線膨脹系數(shù))ofthetwomaterialsaresimilar.3)Theconcretecoverercanprotectthesteelbarsfromrusting(腐蝕).第1、2章習(xí)題課(2學(xué)時)1.3Explaintheadvantagesandthedisadvantagesofreinforcedconcretestructure.（解釋鋼筋混凝土結(jié)構(gòu)的優(yōu)點和缺點）

Advantages:1)durability(耐久性)2）fireresistance(耐火性)3）highstiffness(剛度高)4)locallyavailableresources;(易于就地取材)5)costeffective;6)entirety(整體性好);

Disadvantages:1)largedeadmass(自重大)2)longcureperiod(養(yǎng)護(hù)周期長）

3)easilycracked;(容易開裂)

第1、2章習(xí)題課(2學(xué)時)CHAPTER2MECHANICALPROPERTIESOFREINFORCEDCONCRETEMATERIALS

(鋼筋混凝土材料的力學(xué)性能)1.Problemsforponderation(思考題)2.1Explainthedifferenceofstress-strainrelationshipbetweenthemildsteelbarsandthehardeningsteelbars.(分析有明顯屈服點鋼筋和沒有明顯屈服點鋼筋的應(yīng)力應(yīng)變關(guān)系有何不同)第1、2章習(xí)題課(2學(xué)時)應(yīng)力應(yīng)變曲線d(其對應(yīng)極限抗拉強(qiáng)度)第1、2章習(xí)題課(2學(xué)時)2.2Whythestrengthofthesteelbeyondtheyieldingstrengthcannotbeutilizedandtheyieldingstressisallthestrengthavailableforstructuraldesign?

（在結(jié)構(gòu)設(shè)計中，為何將屈服強(qiáng)度做為鋼筋的強(qiáng)度取值而不能利用超過屈服強(qiáng)度以后的強(qiáng)度）

Whenthestrengthofsteelbeyondtheyieldingstrength,thesteelenterintothestageofflow(塑性流動階段),andthedeformation(變形)willbecomelargerthanbeforedistinctly.Thesteelmayenterthehardeningstage(強(qiáng)化階段),thelargedeformationduringtheflowmakethestructurecan’tbeserviceable.(適用性)

第1、2章習(xí)題課(2學(xué)時)2.3Whatisthecubiccompressivestrength?Explainthefactorsthataffectthe.

（什么是混凝土立方體抗壓強(qiáng)度，影響其強(qiáng)度的主要因素）

Thecubiccompressivestrengthisthecompressivestressofacubicspecimen(試樣)withsidelengthof150mm,curedfor28daysunderstandardtestmethod(temperatureisat20±3,humidity90%),testbythestandardtestmethod(surfaceofspecimenisnotlubricate(潤滑)withgrease(油脂),loadingspeedincreasein0.15~0.25MPa/s).Thefactorsaffectthestrengthofconcrete:1).Thesizeandshapeofthespecimen;2)Ageandcuringconditions;3).ThespeedofStressing;4).Theorientationofstressrelativetodirectionofcasting(荷載方向和澆筑方向的關(guān)系).(5).Theconditionoflateralconstraint.(側(cè)向約束)。

第1、2章習(xí)題課(2學(xué)時)

2.4Whatarethecharacteristicsoftheconstitutiverelationofconcreteincompression?(混凝土受壓狀態(tài)下本構(gòu)關(guān)系的特點)ABC反彎點收斂點殘余應(yīng)力第1、2章習(xí)題課(2學(xué)時)

2.5Howcanwedefinethegradeofconcrete?

（如何確定混凝土強(qiáng)度等級）

Weusethecompressivestrengthtodefinethegradeoftheconcrete.Thecubestrengthofconcreteisclassifiedintofollowing14grades:C15,C20,…C70,C75,C80.The“C”standsfor“concrete”,andthefollowingnumeralsindicatethestandardcubestrengthoftheconcreteinMPa.

.

第1、2章習(xí)題課(2學(xué)時)2.6Listthecharacteristicsofconcretestrengthunderbi-axial（雙軸）ortri-axial（三軸）loads.

（解釋在雙軸受力和三軸荷載的情況下混凝土強(qiáng)度的特點）2.7Explainthetermsofinitialmodulusofelasticity,tangentmodulusofelasticity,thesecantmodulusofelasticityandthecoefficientofelasticity.

（解釋初始彈性模量，切線彈模，割線彈模(變形模量)和彈性系數(shù)）

Theinitialslope(初始角度)ofthetangenttothecurveisdefinedas“initialmodulusofelasticity”.theslopeofthetangenttoapointofthecurveisdefinedas“thetangentmodulusofelasticity”.Andtheslopeofthestraightlinethatconcretestheorigintoapointofthecurveisdefinedas“thesecantmodulusofelasticity”。Inelasticityanalysisthecoefficientofelasticitycanbetakenas“”

第1、2章習(xí)題課(2學(xué)時)2.8Definethetermsofcreepandshrinkageofconcrete.Listthemainfactorswhichinfluencecreepandshrinkage.（什么是混凝土的徐變和收縮，影響它們的主要因素是什么）

Creep:orplasticflow,istheincreaseinstrainwithtimeduetosustainedload(長期荷載).Shrinkage:thevolumeoftheconcreteshrinkwhentheconcreteharden(硬化)intheair.Thefactorswhichinfluencecreepandshrinkageare:1)amountofcement(水泥用量);2)aggregate;(骨料)3)water-cementratio;(水灰比)4)sizeofelement;(構(gòu)件體積)5)mediumambientcondition;(環(huán)境)6)amountofreinforcement;(鋼筋量)7)admixture;(外加劑)8)typeofcement.(水泥種類)第1、2章習(xí)題課(2學(xué)時)2.9Listthefactorsaffectedthebondstrengthbetweentheconcreteandsteel.（列出影響鋼筋和混凝土之間的粘結(jié)的因素）

1)adhesion(粘結(jié)力)betweentheconcreteandreinforcingelement.2)grippingeffectresultingfromthedryingshrinkageofthesurroudingconcreteandtheshearinterlockbetweenthebardeformationsandthesurroundingconcrete.3)frictional(摩擦力)resistancetoslidingandinterlocksthatthereinforcingelementissubjectedtotensilestress.4)effectofconcretequalityandstrengthintensionandcompression.5)mechanicalanchorageeffect(錨固作用)oftheendsofbarsthroughdevelopmentlength,splicing,,hooks,andcrossbars.6)Diameter,shape,bondlength,andspacingofreinforcementastheyaffectcrackdevelopment.7)Thepercentageratioandyieldingstrengthofthestirrups.(箍筋)8)Theheightofthecoveredconcretenearembeddedreinforcementofconcretemembers.(保護(hù)層厚度)第1、2章習(xí)題課(2學(xué)時)

2.10Definethetermofthedevelopmentlengthofreinforcement.

（鋼筋錨固長度的定義）

Theembeddedlengthofthereinforcementmustbesufficienttothedevelopmentbythebondofmaximumtensileforceinthereinforcement.Thelengthrequiredtodeveloptheyieldstrength(屈服強(qiáng)度)ofthereinforcementiscalledthedevelopmentoranchorage(錨固)length.第1、2章習(xí)題課(2學(xué)時)2.Problemsforsolution(計算題)2.1.Astress-strainrelationshipisshownasthefollowing,thestress-straincurveofascendingsegmentis

,andthatofdescendingsegmentis,theaxially-compressivestrengthofconcreteis,findthevalueofinitialmodulusofelasticity.ifthestressofconcreteatpointCis,findthevaluesoftangent(切線)modulusofelasticity,thesecantmodulusofelasticityandthecoeffici