江苏科技大学：《结构力学》课程教学课件（讲稿）第03章 静定结构的受力分析

江蘇科技大学jiangsu university of sclence and technology先讨论简支梁qBMAMITMMMOATOBMMo1ⅡIqIBTOBbAMo+十BMATM.ToBOAMI1 School of Civil Engineering and Architecture

11 School of Civil Engine School of Civil Engineering and Architecture ring and Architecture A B MA MB q A B q A B MA MB = + A 0 B M A B M 0 M MA M MB A B MA MB = + 先讨论简支梁

江蘇科技大学jiangsu university of sclence and technology讨论结构中任意直杆段的弯矩图qFPFO=F+t++ttJAFOA&YA经计算得：BOFoFys=FoB图(a)所以图（b）q（c）的M图均为：MMBFBNBAIM.MMaFQBQA图 (b)图 (d)qM弯矩图的绘制方法：MorB求控制截面的弯矩FOFoyAJB分段画弯矩图图 (c)12 School or Civil Engineering ang Architecture

12 School of Civil Engine School of Civil Engineering and Architecture ring and Architecture 讨论结构中任意直杆段的弯矩图 A B FP q 图(a) A B q FNB FQB MB FNA M A FQA 图(b) A B M A M B q 0 FyA 0 FyB 图(c) 经计算得：       yB QB yA QA F F F F 0 0 所以图（b）、 （c）的M图均为： A B M A M M B 0 M M 图(d) 弯矩图的绘制方法: ◆求控制截面的弯矩 ◆分段画弯矩图

江蘇科技大学jiangsuuniversityof sclence andtechnology【例3.1】试求图示梁的内力图8KN4KN/m16KN·mllltllltllBCDEFTOrGO7A2m2m1m1m| 1mmFRG = 7kNFRA=17kN解：Stepl:求支反力,由梁的整体平衡条件可求出。[F,=17KNEM,=0Fr-8+16-4.4.4-8.1=0RAZY=0FRGFra+FRG-8-4.4=0G=7KN.Step2:求控制截载面的弯矩和剪力。选A、BL、BR、C、E、FL、FR、G为控制截面，设弯矩下侧受拉为正

13 School of Civil Engine School of Civil Engineering and Architecture ring and Architecture A B C D EF G 8KN 4 KN m 16KN  m 1m 1m 2m 2m 1m 1m FRA 17kN FRG  7kN 解: 【例3.1 】 试求图示梁的内力图 Step1:求支反力,由梁的整体平衡条件可求出。                    F KN F KN F F F YM RGRA RA RG A RG 717 8 4 4 0 8 16 4 4 4 8 1 0 0 0 Step2： 求控制截面的弯矩和剪力。 选A、BL、BR、C、E、FL、FR 、G为控制截面，设弯矩下侧受拉 为正

江蘇科技大学jiangsu university of sclence and technologyMEM =0M, =0KN·mZY=0FoA=17KNOA17kNMLZM.=0M, =17KN·mZY=0FL =17KNQBOF17kN8KNMRMR=17KN.mZM,=0A BZY=0FR =9KNFROBQB17kN8KNZM,=0M. =26KNmM.ZY=0Foc=9KNBFQC17kN14 School of Civil Engineering and Architecture

14 School of Civil Engine School of Civil Engineering and Architecture ring and Architecture     0 0 Y MA F KN M KN m QA A 17 0        0 0 Y MB F KN M KN m L L B QB 17 17    A B L QB F L M B 17 kN A FQA M A 17 kN A B 8KN 17 kN R QB F R M B     0 0 Y MB F KN M KN m R R B QB 9 17    A B 8KN 17 kN C QC F M C     0 0 Y MC F KN M KN m QC C 9 26   

江蘇科技大学jiangsu university of sclence and technologyM,16KN·mZM,=0M,=30KN·moGZY=0Foe=-7KNAQE17kN16KN·mMLM'=23KN·mZM,=0FTorGZY=0FL =-7KNQFQF7kNMRMR=7KN.mZM,=0FrGFRZY=0FR =-7KNQFO7kNMZM=0MG=0OrGZY=0Foc=-7KNOG7kN1s School of Civil Engineering and Architecture

15 School of Civil Engine School of Civil Engineering and Architecture ring and Architecture F G 16KN  m 7 kN L M F L QF F EFG 16KN  m 7 kN M E FQE     0 0 Y ME F KN M KN m QE E 7 30         0 0 Y MF F KN M KN m L L QF F 7 23     F G 7 kN R M F R QF F     0 0 Y MF F KN M KN m R R QF F 7 7         0 0 Y MG F KN M QG G 7 0    G 7 kN FQG M G