江蘇科技大学jiangsu university of sclence and technologyBLBRDLDEAcEF0弯矩M00-F,a-F,a0.5 F,a0.5 F,a-0.25 F,a剪力FQ-Fp0.5F0.5F0.5F,-0.25F,-0.25F,-0.25FDLPDpp3：绘制内力图。F,a0.5F,0.25F,aDFDE AGOBQCCABFE0.5Fa0.25FpFpM图F图26 School of Civil Engineering and Architecture
26 School of Civil Engine School of Civil Engineering and Architecture ring and Architecture 3:绘制内力图。 AB C D E F FPa 0.25FPa 0.5FPa M图 A B C D E F FP FP 0.25 5FP 0. FQ图 D E F A BL BR C DL E 0.5Fp 0.5 Fpa -0.25Fp 0.5 Fpa 0.5Fp -Fpa 0.5Fp 0 -0.25Fp -0.25Fp -Fp 剪力FQ -Fp -0.25 Fp -F 0 a p 弯矩M 0 a
江药科技大学jiangsu university of sclence and technology【例3.3】试求铰D的位置，使负弯矩峰值与正弯矩峰值相等qqqDB-xxToB解：1：确定支承关系，求支反力。qt对AD部分：DqRDZMA=0FRp = 0.5q(l- x)BFZY=0FR4 = 0.5q(l - x)RAFFRCRB27 School of Civil EngineeringandArchitecture
27 School of Civil Engine School of Civil Engineering and Architecture ring and Architecture 解： 【例3.3 】 试求铰D的位置，使负弯矩峰值与正弯矩峰值相等 1: 确定支承关系，求支反力。 A D B C q l x x l A D B C q q A D B C q q FRA FRD FRB FRC 对AD部分： 0 0 Y M A 0.5 ( ) 0.5 ( ) F q l x F q l x RA RD
江蘇科技大学2：设弯矩下侧受拉为正，求AD跨的正弯矩及B截面的负弯矩。q+++++++++++tq0.5g(l-x)B0.5q(1-x)FRRCRB9r2g(l-x, M,=gl-x)xM跨中得:822gr2q(l -x)2_ q(l - x)x=MBM跨中x = 0.172lB8223：绘制内力图。0.086q12M图DB0.086qlQ.086al328 SchoolofCivil EngineeringandArchitecture
28 School of Civil Engine School of Civil Engineering and Architecture ring and Architecture 2：设弯矩下侧受拉为正，求AD跨的正弯矩及B截面的负弯 矩。 A D B C q q 0.5q(l x) FRB FRC 0.5q(l x) 2 2 ( ) 8 ( )2 2 q l x x qx M q l x M B 跨中 ， 2 2 ( ) 8 ( )2 2 q l x q l x x qx M MB 跨中 得： x 0.172l A DB C 2 0.086ql 2 0.086ql 2 0.086ql M图 3:绘制内力图
江蘇科技大学jiangsu university of sclence and technology83-3静定平面桁架.架的计算简图南京长江大桥29 School of Civil Engineering and Architecture
29 School of Civil Engine School of Civil Engineering and Architecture ring and Architecture §3-3 静定平面桁架 一.桁架的计算简图 南京长江大桥
江蘇科技大学jiangsu university of sclence and technology在桁架的内力计算中，采用下列假定：桁架的结点都是光滑的铰结点；各杆的轴线都是直线并通过铰的中心；荷载和支座反力都作用在结点上PNL式杆EDFyA30 School of Civil Engineering andArchitecture
30 School of Civil Engine School of Civil Engineering and Architecture ring and Architecture 在桁架的内力计算中，采用下列假定： 桁架的结点都是光滑的铰结点； 各杆的轴线都是直线并通过铰的中心； 荷载和支座反力都作用在结点上。 桁式杆