混凝土结构设计1

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1、混凝土结构原理韩仲CHAPTER1INTRODUCTION(绪论)1.1BasicConceptsandCharacteristicsofReinforcedConcrete(钢筋混凝土的基本概念及特点)1.Concrete(混凝土)(1)Plainconcreteisformedfromhardenedmixtureofcement,water,fineaggregate,coarseaggregate(crushedstoneorgravel),air,andoftenotheradmixtures(外加剂).(2)Concretehashighcompre

2、ssivestrengthandlowresistancetotension.Itstensilestrengthisapproximatelyone-tenthofitscompressivestrength.2.ReinforcedConcrete(钢筋混凝土)Consequently,tensilereinforcementinthetensionzonehastobeprovidedtosupplementthetensilestrengthofthereinforcedconcretesection.(1)Aplainconcretebeamunder

3、auniformlydistributedload●Whenthedistributedloadincreasesandreachesavalue=1.37kN/m,thetensileregionatthemid-spanwillbecrackedandthebeamwillfailsuddenly.(2)Areinforcedconcretebeamofthesamesizebuthastwosteelreinforcingbars(216)embeddedatthebottomunderauniformlydistributedload●Thereinf

4、orcingbarstakeupthetensionthereaftertheconcreteiscracked.●Whentheloadisincreased,thewidthofthecracks,thedeflectionandthestressofsteelbarswillincrease.●Whenthesteelapproachestheyieldingstressthedeflectionandthecrackwidtharesolargeofferingsomewarningthatthebeamisgoingtofail.Thefailureo

5、fthebeamischaracterizedbythe5混凝土结构原理韩仲crushingoftheconcreteinthecompressionzone.●Thefailureload=9.31kN/m,isapproximately6.8timesthatfortheplainconcretebeam.*Somekindsofconcrete①Plainconcrete(素混凝土)；②Reinforcedconcrete(钢筋混凝土)；③Pre-stressingconcrete(预应力混凝土)；④Fiberreinforcedconcrete(纤维混凝

6、土)。3.Thereasonsthattheconcreteandreinforcementcanworktogether(钢筋和混凝土能够共同工作的原因)(1)Thereisasufficientlystrongbondbetweenthetwomaterials;(钢筋和混凝土之间存在很强的粘结力)(2)Thethermalexpansioncoefficientsofthetwomaterialsareapproximatelyequal(1.2K-1forsteeland1.0-1.5K-1forconcrete).(钢筋和混凝土温度线膨胀系数接近)4.

7、Thefeaturesofreinforcedconcretestructure(钢筋混凝土的特点)（1）Durability(耐久性).Withthereinforcingsteelprotectedbytheconcrete,reinforcedconcreteisperhapsoneofthemostdurablematerialsforconstruction.Itdoesnotrotorrust,andisnotvulnerabletoefflorescence.（2）Fireresistance(耐火性).Bothconcreteandsteelar

8、enotinflamma