Chapter4Internalforcesinbeams弯曲内力学习培训模板课件.ppt

1、234567 8AB对称轴对称轴纵向对称面纵向对称面梁变形后的轴线与梁变形后的轴线与外力在同一平面内外力在同一平面内梁的轴线梁的轴线FRAF1F2FRB9。FAAAA10AAAFRAyAFRAxFFM11 1213 BAalFFFFRBABF,(),RRR0000 xAxAByAyFFFaMFlF laFFl14MFRAxFABFmmxRAyFSCFFRBFSCM(),SRR00yAyCAyF laFFFlMMFx15FSdxmmFS+dxmmFSFS16；mm+MMmm（受压）（受压）MM170AMFRBBdEDAabclCFF1F2FRA021R bFaFlFB0BM0)()(21R bl

2、FalFlFAlblFalFFA)()(21R lbFaFFB21R 18 BdEDAabclCFF1F2FRAAEcFSEFRA00SR EAyFF,F0,0R cFMMAEEAEFFRS cFMAE R19AEcFSEFRAa-cb-cCDl-cBEFSEF1F2 0yF021RS FFFFBE0ME0)()()(21R McbFcaFclFEB+cFMAE RAEFFRS 20 BdEDAabclCFF1F2FRAFdBFSFMFFRB,SRR0000yFBFFBFFFMMFd-+BFFFRS dFMBFR 21 niiFF左（右）1S 22 mkkiniiMaFM左（右）左（右）左（右

3、）左（右）1123F2=FACDBbacF1=FFF kN60RR FFFBA24F2=FACDBbacF1=FFRBkN601SFFCmkN061 .bFMC060601RS FFFADmkN8.13)(1R FacFacFMAD25C12MkN4RSS1 ACFFF左mkN41R1 ACFMM左kN4)4(RS2S BCFFF右mkN651)4()152(R2 .FMMBC右B1m2.5m10kNmAC12FF26 27 xFS(x)FS 图的坐标系图的坐标系OM 图的坐标系图的坐标系xOM(x)28BAFlx)0()()0()(SlxFxxMlxFxF 0SFA左左FFA 右右SFSxF

4、FlxM292RRqlFFBA lqFFABx)0(222)()0(2)(2RRSlxqxqlxxqxxFxMlxqxqlqxFxFAA 30)0(2)(SlxqxqlxF2SqlF 2SqlF +ql/2ql/2BlqFAxF31)0(222)(2RlxqxqlxxqxxFxMA lqFABxF00 Mx，0,Mlx()d0d2M xqlqxx2lx 822maxqlMMlx+82qll/232 lqFABxF+ql/2ql/2+82qll/282maxqlM2maxSqlF33lFABCabFFlFbFA RlFaFB R34 xxlFABCabFRAFRB)2()0()()1()0()(

5、SaxxlFbxMaxlFbxF )4()()()()()3()()()(SlxaxllFaaxFxlFbxMlxalFalblFFlFbxF 35)1()0()(SaxlFbxF)3()()(SlxalFaxF xxlFABCabFRAFRB+lFblFa)4()()()(lxaxllFaxM )2()0()(axxlFbxM+lFba36xxlFABCabFRAFRB+lFbalFblFa37R AMFlR BMFl()()()S01MFxxlllABCabFRAFRBM+Ml38xxlABCabFRAFRBM()MM xxl)0(ax()()MMM xx Mlxll)(lxa CMaMl

6、左左 0M CMbMl右右+MalMbl39lABCabFRAFRBM+/M l+MalMbl4041ABFlxlxlFFA)(R lFxFB RxlxlFxFMAC)(R 0ddxMC0)2(xllF2lx 422lx xlxlFxFMAC)(R FlM41max43xyq(x)FM44xyq(x)FMFS(x)M(x)FS(x)+dFS(x)M(x)+dM(x)mmnnq(x)C.nxmmn dx4502d)d(d )()()(d)(0 S xxxqxxFxMxMxMMCFS(x)M(x)FS(x)+dFS(x)M(x)+dM(x)mmnnq(x)C0d)()(d)()(0SSS xxqx

7、FxFxFFx )(d)(dSxqxxF)(d)(dSxFxxM46)(d)(dSxqxxF)(d)(dSxFxxM)(d)(d22xqxxM47xFS(x)OxOM(x)(d)(dSxqxxF)(d)(dSxFxxM)(d)(d22xqxxM48xFS(x)OxOM(x)(d)(dSxqxxF)(d)(dSxFxxM)(d)(d22xqxxMOM(x)x49)(d)(dSxqxxF)(d)(dSxFxxM)(d)(d22xqxxM50FCMC或或q0FMC51)(d)(dSxqxxF()()2211SddxxxxFxq xx()()()21S2S1dxxFxFxq xx()()()21S2S

8、1dxxFxFxq xx52)(d)(dSxFxxM()()()21S21dxxFxxM xM x()()()21S2S1dxxFxFxq xx)()(2S1SxFxF53k623R.FA kN27R BFBACD2001151265FFFF231kN6.23RS AAFF右5423.61.727+BFRBACD2001151265FFFRA231kN27RS BDFF右kN0S右右BFkN27SmaxFkN7.1RS FFFAC右554.723.11+BACD2001151265FFFRAFRB231mkN11.3115.0R BDFM0MBmkN72.4max MmkN72.42.0R A

9、CFM0MA56BACD2001151265FFFRAFRB2314.723.11+23.61.727+57 FEqABCD0.21.612kN806.11005.0RR BAFF58+80kN80kNkN80RS AAFF右 kN80RS ACFFkN80RS BDFFkN80RS左 BBFFkN0S右右BF kN80maxS FFEqABCD0.21.612593m4mABCDE4m4mFRAFRBF1=2kNq=1kN/mM=10kNmF2=2kNkN7R AFkN5R BFkN7RS AAFF右kN34RS qFFAC左kN141RS FqFFAC右kN3R2S BDFFF603m4m

10、ABCDE4m4mFRAFRBF1=2kNq=1kN/mM=10kNmF2=2kNkN3R2S BFFFkN22S FFB右kN7S 右右AFkN3S 左左CFkN1S 右右CFkN3S DF01RS FqxFFAx7kN1kN+3kN3kN2kNx=5m610MA 2R7164DBMFMF左左5.20maxMMF647R2 BDFFM右632 FMB0 ME201666+20.53m4mABCDE4m4mFRAFRBF1=2kNq=1kN/mM=10kNmF2=2kN204242R qFMAC623m4mABCDE4m4mFRAFRBF1=2kNq=1kN/mM=10kNmF2=2kN7kN

11、1kN+3kN3kN2kNx=5m201666+20.56310.5113F=50kNM=5kNmAECDKBFRAFRBMAq=20kN/m64 81kN31kN29kN+10.5113F=50kNM=5kNmAECDKBFRAFRBMAq=20kN/m650RS qxFFBxm45.1R qFxBx=1.4581kN31kN29kN+10.5113F=50kNM=5kNmAECDKBFRAFRBMAq=20kN/m66kN mAAMM右右9 96 6.5 5mkN5.15181MMAE05.031MMECmkN31131MMCD96.515.53110.5113F=50kNM=5kNmAE

12、CDKBFRAFRBMAq=20kN/m67 R1KBFMMmkN345129.maxR2 45BMFMmkN5545.122q5kN mBMM左左0MB右右96.53115.5x+5534510.5113F=50kNM=5kNmAECDKBFRAFRBMAq=20kN/m68+10.5113F=50kNM=5kNmAECDKBFRAFRBMAq=20kN/m69abcd18kN2kN14kN3m3m6m+()SddFq xxkN18SFB左左kN2S FB右右CABDF=20kN70()SddFq xx()SSd6dDCcq xxqFFkN/m26)2()14(qabcd18kN2kN14k

13、N3m3m6m+q=2kNCABDF=20kN71)(d)(dSxFxxM()SdbBAaMMFxxmkN543180abcd18kN2kN14kN3m3m6m+cbSBCxxFMMd)()542348 kN m0Md48dab54c+7240kNmabcd2m2m2m+)(d)(dSxFxxM()SSd2cCBbFxxFMMS0 4020kN22CBMMFabcd20kN73Me)(ddxqxFS0MA左左mkN40右右AM40KNmabcd2m2m2m+abcd20kNBCAD0SFB左左kN20SFB右右kN20SFB左左0SFB右右FF74)()()(),(Sn21S11S21SnnF

14、FFFFFFFFF (,)()()()121122nnnM F FFM FMFMF75xF=ql/3ql76xF=ql/3ql2)(2qxFxxMxqxFxxMF)(2)(2qxxMq2)(2qxFxxM77Fxqxlqx+FxxMF)(Fl2)(2qxxMq22ql+-62ql62ql812ql78BCF2F3aDEF1AaaaF1291acebdF2e122+acbd215acebdF3aaaa79291acebdmkN1312152112229121)()(MCBCF2F3aDEF1Aaaa122+acebd215acebd291215131acebd80ABC8182alF1F2ABC

15、M(x)FN(x)FS(x)CxF1x83alF1F2ABCFS(x)CBaF1F2FN(x)M(x)x840 FN图图F1|CalF1F2ABFS图图F1+F2+85CalF1F2ABF1aF1aF1a+F2l 8687FOR ScosFF NsinFF sinMFR 0sin0N FFFn0cos0S FFFt0sin0CMMFR FtnC FNFS O+MFR88q qmmxOFRAB()()()()cos1cos0MFxF RRFRqqqqqqqq()()S1sin0FFFqqqqqq()()N2cos0FFFqqqqqq 89O+FS图图ABOM图图2FROFN图图FF+xOFRq qmmAB()()()()cos1cos0MFxF RRFRqqqqqqqq()()S1sin0FFFqqqqqq()()N2cos0FFFqqqqqq