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1()2()3()4()5()6()7()8()9.()10.AB()12.()13()14R'F=00OM()15R'F0OM=0()16()17()18()19()20()21()22()23.()24.()25()26.()272829.()300()31.()33.()3435363738394041425%431234567.33112281________23__________9RM,__O________R=0_M=0____101_____23____12.___________________13.1_______2______3_____14.dIZ=__D^4/64______IP=___D^4/32_________WZWP__1:2_15.16.cabcd17.18.19.20.zIMy,zI,y,21.22.pI,,PI,,23.24.R()()OOMMFF25.27n(n-1)AA2829300FsFsmax31323337______38______________39____________40_____________________41____________42______________43.044.46-12347.4548.GIp49.-s=__235____Mpa2[]=___118__Mpa50.5152NKN5NmKNm5455565758596061626364656667681(a)(b)(c)(d)(c)P(a)P(b)P(c)P(d)2ABmmnn1P2P(A)1P2PmmnnBA(A)AB(B)AB(C)AB(D)AB3(C)(A)(a)(b)(B)(b)(c)(C)(a)(c)(D)(c)(d)2F1F3F(a)2F1F3F(b)1F2F3F4F(c)1F2F3F4F(d)4.(B)(A)(B)(C)(D)5(D)(A)(B)(C)(D)60xF(A)(A)x(B)x(C)y(D)y7FOABCxyz(C)(A)0)(FxM0)(FyM0)(FzM(B)0)(FxM0)(FyM0)(FzM(C)0)(FxM0)(FyM0)(FzM(D)0)(FxM0)(FyM0)(FzM8MPa1MpaBA103Nm2B106Nm2C109Nm2D1012Nm29lqCABCD10CA.B.CD11.BABCD12.(A).A.B.C.,D.,13.ABCP?ABCBA.B.C0D.0A14.450(D)A./2B.C./2D./2155KN350FKNF5,AA.B.yOxzFABC.D.16DA.B.C.D.17DA.B.C.D.18BABCD19BABCD2a2a2a2a1234571n8FYFFxFYYFXFYFXFXFXFxFYFYFYFY9101113=FN/A[[]1231412341.BCABAB21cm100AMPa71BC22cm6AMPa1602F,3,2FFFFABBC5AB,4.40KNF4BCKNF484kNF4.4012G=1.8kNABCF030CABB10cm30cm20cm45CGAD3ABACDEDEEF2kNACM1kN.m,AD=BD=1mHDEDH01niixF0BxFiiBFM0,022MFmFCykNFCy5.1kNFBy5.0AB0)(1iniAFm0ADFABFDXBx0DxFDE01niixF0HxDxFF0HxF0)(1iniDFm02DHFFHyKNFHy443.33(a)(b)ABCDAB=BC=AD=250mmR=100mmW=1000NADABWC45D(a)5ABd=2cm,L=1mq=500N/m,[]=100MPa0)(FMA,mNqLMqLMAA25020222AmNMMA250maxLBAqdAZCZWMWMmaxmax323dWZMPaMPaWMWMZCZ100][31.3181010232250363maxmax6ADF1=100KNF2=80KNF3=60KN,F1F2F3BCD1m3m1.5m1niFi10FN+F1-F2+F3=0FN=-F1+F2-F3=-100+80-60=-80kN2ABniFi10N1-FN=0N1=FN=80kN()BCniFi10N2+F1-FN=0N2=FN-F1=-20kN()CDniFi10-N3+F3=0N3=F3=60kN3++-7,mm12d6mmMPa140=][,MPa240=][jy8d=80mmb=20mmh=12mml=120mm,[]=40Mpa[jy]=90MpaM=2kNm159.ABCDBCEFd.d25mmQ235[]160MPa.[FP].10E=200GPa21200Amm22300Amm23400AmmCD320NFkN333963201010.000250.252001040010NCDFllmmmEACB210NFkN32296210101.50.000250.252001030010NCBFllmmmEAAB110NFkN311961101010.000250.252001020010NABFllmmmEA1230.25llllmm10kN20kN20kN1.5m1m1m3A2A1ABCDAN2224EFFdFN1=0.8FP,FN2=1.9FP2266P3301016010N41.941.959.5210N59.52kNdFP=59.52kNF