4FlexuralStrengthofReinforcedConcreteMemberswithFlexureandShear受弯构件正截面承载力计算WanShengwuWanShengwuDepartmentofCivilEngineering,WUSTDepartmentofCivilEngineering,WUST2011.092011.09CONCRETESTRUCTURALFUNDAMENTALS混凝土结构设计原理4FlexuralStrengthofRCMemberswithFlexureandShearContentsContents4.1Preface概述4.2BasicDetailingofRCMemberswithFlexureandShear受弯构件基本构造要求4.3AnalysisforNormalSectionofFlexuralMembersunderLoading受弯构件正截面受力过程分析4.4CalculationforNormalSectionofFlexuralMembers受弯构件正截面承载力计算4.5CalculationforRectangularSectionBeamwithTensionReinforcementonly单筋矩形截面受弯构件正截面承载力计算4.6RectangularBeamwithCompressionReinforcement双筋矩形截面受弯构件正截面受弯承载力计算4.7T-SectionBeamwithTensionReinforcementonlyT形截面受弯构件正截面受弯承载力计算EEmphasesmphases•AnalyzeofFlexuralStrength•StudyonTest•Rectangularbeamwithtensionreinforcementonly•Rectangularbeamwithcompressionreinforcement•Flangedsectionbeamwithtensionreinforcementonly4.1Preface4.1PrefaceFlexuralMembers受弯构件:承受荷载作用下产生的弯矩(M)和剪力(V)的构件。常见Beamandslab正截面NormalSection:垂直于轴线的截面。受力特点:受弯构件在M作用下容易产生正截面破坏,在M和V共同作用下容易产生斜截面破坏。受弯构件设计问题:保证构件在M作用下不发生正截面破坏(本章);保证构件在M和V共同作用下不发生斜截面破坏(第5章);保证构件在荷载作用下能满足正常使用的要求(第9章)本章要解决的问题通过结构计算确定构件的截面尺寸、纵向受力钢筋的数量以及满足相应的构造要求和绘制施工图。Flexuralmembers——Beamandslab4.1PrefaceBeamBeam4.1PrefaceSlabSlab4.1Preface4.2BasicDetailingof4.2BasicDetailingofRCMembersRCMemberswithFlexureawithFlexureandShearndShear受弯构件的基本构造要求受弯构件的基本构造要求4.2.1DetailingofBeam(1)TypsofSectionRectanglesection4.2BasicDetailingofRCMemberswithFlexureandShearT-section、I-section、Coss-sectionOthersL-section、-section、Γ-section、Basket-section(2)Sizeofsection满足承载力和刚度要求Depthofbeam’ssectionh:按梁的连接方式不同,依据跨度确定。Example,简支梁h=L/12,悬挑梁h=L/6,框架梁和连续梁另外有规定。为施工方便,截面高度应符合模数,h=200,250,300,……等,以50mm模数递增;当h>800mm时,以100mm模数递增。Widthofbeam’ssectionb:h确定后,b按h/b确定。Rectanglesection:b=(1/2~1/4)h;T-section:b=(1/2.5~1/4)h梁宽b同样应符合模数要求,b=150,200,250,……等,以50mm模数递增,特殊情况,如圈梁b可以取为墙体宽度。4.2BasicDetailingofRCMemberswithFlexureandShear(3)SteelbarinBeam①LongitudinalmainbarLongitudinalReinforcementwithTension:布置在梁的受拉区,抵抗W在正截面产生的拉应力;LongitudinalReinforcementwithCompression:布置在梁的受压区,协助砼抵抗W在正截面产生的压应力。设计要求:普通钢筋砼梁中一般采用直径10~25mm之间的钢筋,级别HRB335(II)、HRB400(III)。但对于承力构件,受拉钢筋d宜大于12mm,受压钢筋宜大于14mm。同一跨度的梁中间可以采用直径不同的钢筋,但直径种类不宜超过2种。对于受拉纵筋宜采用直径较小的钢筋,以利于抗裂度要求。4.2BasicDetailingofRCMemberswithFlexureandShear②StirrupandBentupofmainbar抵抗剪力作用,下章介绍。③LongitudinalTierod作用:固定箍筋的正确位置并形成钢筋骨架,保证施工时必要的刚度;抵抗可能有的比较小的弯矩和温度变化产生的裂缝。设置:按构造要求设置,一般设置两根,置于截面受压区域角部。直径按照跨度确定,一般不小于10mm。如果截面配置有受压钢筋,架立筋不再单独另设,受压钢筋可以兼做架立筋。4.2BasicDetailingofRCMemberswithFlexurea...