第1、2章习题课(2学时)课件

——混凝土结构原理(1-2章)第1、2章习题课(2学时)CHAPTER1INTRODUCTION(绪论)1.Problemsforponderation(思考题)1.1Explaintheeffectofthattheconcretebeamhassteelreinforcingbarsembeddedatthebottomunderloading.

（解释在底部配有钢筋的混凝土梁在荷载作用下的影响）

Aplainconcretebeamunderloadingwillbecrackedatthetensionregionofthemid-span(跨中)andthebeamwillfailsuddenlywhentheloadreachit’slimitvalue.Butreinforcingbarsembeddedatthebottomoftheconcretebeamcantakeupthetensionthereaftertheconcreteiscracked.whenthesteelapproachesyieldingstress,thecrackaresolargeofferingthewarning(预警)thatthebeamisgoingtofail.提高梁的承载能力和变形能力第1、2章习题课(2学时)

1.2Whycanworktogethertheconcreteandreinforcement?(钢筋和混凝土为什么可以共同工作）

Concreteandreinforcecanworktogetherbecause:1)Thereisasufficientlystrongbondbetweenthetwomaterials.2)Thethermalexpansioncoefficients(线膨胀系数)ofthetwomaterialsaresimilar.3)Theconcretecoverercanprotectthesteelbarsfromrusting(腐蚀).第1、2章习题课(2学时)1.3Explaintheadvantagesandthedisadvantagesofreinforcedconcretestructure.（解释钢筋混凝土结构的优点和缺点）

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

Disadvantages:1)largedeadmass(自重大)2)longcureperiod(养护周期长）

3)easilycracked;(容易开裂)

第1、2章习题课(2学时)CHAPTER2MECHANICALPROPERTIESOFREINFORCEDCONCRETEMATERIALS

(钢筋混凝土材料的力学性能)1.Problemsforponderation(思考题)2.1Explainthedifferenceofstress-strainrelationshipbetweenthemildsteelbarsandthehardeningsteelbars.(分析有明显屈服点钢筋和没有明显屈服点钢筋的应力应变关系有何不同)第1、2章习题课(2学时)应力应变曲线d(其对应极限抗拉强度)第1、2章习题课(2学时)2.2Whythestrengthofthesteelbeyondtheyieldingstrengthcannotbeutilizedandtheyieldingstressisallthestrengthavailableforstructuraldesign?

（在结构设计中，为何将屈服强度做为钢筋的强度取值而不能利用超过屈服强度以后的强度）

Whenthestrengthofsteelbeyondtheyieldingstrength,thesteelenterintothestageofflow(塑性流动阶段),andthedeformation(变形)willbecomelargerthanbeforedistinctly.Thesteelmayenterthehardeningstage(强化阶段),thelargedeformationduringtheflowmakethestructurecan’tbeserviceable.(适用性)

第1、2章习题课(2学时)2.3Whatisthecubiccompressivestrength?Explainthefactorsthataffectthe.

（什么是混凝土立方体抗压强度，影响其强度的主要因素）

Thecubiccompressivestrengthisthecompressivestressofacubicspecimen(试样)withsidelengthof150mm,curedfor28daysunderstandardtestmethod(temperatureisat20±3,humidity90%),testbythestandardtestmethod(surfaceofspecimenisnotlubricate(润滑)withgrease(油脂),loadingspeedincreasein0.15~0.25MPa/s).Thefactorsaffectthestrengthofconcrete:1).Thesizeandshapeofthespecimen;2)Ageandcuringconditions;3).ThespeedofStressing;4).Theorientationofstressrelativetodirectionofcasting(荷载方向和浇筑方向的关系).(5).Theconditionoflateralconstraint.(侧向约束)。

第1、2章习题课(2学时)

2.4Whatarethecharacteristicsoftheconstitutiverelationofconcreteincompression?(混凝土受压状态下本构关系的特点)ABC反弯点收敛点残余应力第1、2章习题课(2学时)

2.5Howcanwedefinethegradeofconcrete?

（如何确定混凝土强度等级）

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

.

第1、2章习题课(2学时)2.6Listthecharacteristicsofconcretestrengthunderbi-axial（双轴）ortri-axial（三轴）loads.

（解释在双轴受力和三轴荷载的情况下混凝土强度的特点）2.7Explainthetermsofinitialmodulusofelasticity,tangentmodulusofelasticity,thesecantmodulusofelasticityandthecoefficientofelasticity.

（解释初始弹性模量，切线弹模，割线弹模(变形模量)和弹性系数）

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

第1、2章习题课(2学时)2.8Definethetermsofcreepandshrinkageofconcrete.Listthemainfactorswhichinfluencecreepandshrinkage.（什么是混凝土的徐变和收缩，影响它们的主要因素是什么）

Creep:orplasticflow,istheincreaseinstrainwithtimeduetosustainedload(长期荷载).Shrinkage:thevolumeoftheconcreteshrinkwhentheconcreteharden(硬化)intheair.Thefactorswhichinfluencecreepandshrinkageare:1)amountofcement(水泥用量);2)aggregate;(骨料)3)water-cementratio;(水灰比)4)sizeofelement;(构件体积)5)mediumambientcondition;(环境)6)amountofreinforcement;(钢筋量)7)admixture;(外加剂)8)typeofcement.(水泥种类)第1、2章习题课(2学时)2.9Listthefactorsaffectedthebondstrengthbetweentheconcreteandsteel.（列出影响钢筋和混凝土之间的粘结的因素）

1)adhesion(粘结力)betweentheconcreteandreinforcingelement.2)grippingeffectresultingfromthedryingshrinkageofthesurroudingconcreteandtheshearinterlockbetweenthebardeformationsandthesurroundingconcrete.3)frictional(摩擦力)resistancetoslidingandinterlocksthatthereinforcingelementissubjectedtotensilestress.4)effectofconcretequalityandstrengthintensionandcompression.5)mechanicalanchorageeffect(锚固作用)oftheendsofbarsthroughdevelopmentlength,splicing,,hooks,andcrossbars.6)Diameter,shape,bondlength,andspacingofreinforcementastheyaffectcrackdevelopment.7)Thepercentageratioandyieldingstrengthofthestirrups.(箍筋)8)Theheightofthecoveredconcretenearembeddedreinforcementofconcretemembers.(保护层厚度)第1、2章习题课(2学时)

2.10Definethetermofthedevelopmentlengthofreinforcement.

（钢筋锚固长度的定义）

Theembeddedlengthofthereinforcementmustbesufficienttothedevelopmentbythebondofmaximumtensileforceinthereinforcement.Thelengthrequiredtodeveloptheyieldstrength(屈服强度)ofthereinforcementiscalledthedevelopmentoranchorage(锚固)length.第1、2章习题课(2学时)2.Problemsforsolution(计算题)2.1.Astress-strainrelationshipisshownasthefollowing,thestress-straincurveofascendingsegmentis

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