8-2位移法I 直接平衡法 ✉> g-20kN/m 40 B D 5Io C40 3L0 3Io E 4m 5m 4m MB=2ic4+4iB42+M6B=241+442+41.7 McD 3icDA=3A2 Mcr 4icrA2=242 MBE =4iBEA=341 MFc=2iFc42=△2 MEB=2iEB△=1.541
8-2位移法Ⅰ——直接平衡法 1 2 1 2 2 4 2 4 41.7 F M i i M CB BC BC CB = + + = + + 2 2 3 3 M i CD CD = = 1 1 4 3 M i BE BE = = 1 1 2 1.5 M i EB EB = = q=20kN/m A 4m 4m 6m 5m 4m B C D E F 4I0 5I0 4I0 3I0 3I0 2 2 4 2 M i CF CF = = 2 2 2 M i FC FC = =
8-2位移法I—直接平衡法 ✉D> (3)建立隔离体平衡方程，求基本未知量 M(是)r MBa+MBE +MBC =0 MBE 10☑+242-1.7=0.(a) MCB+Mcr+MCD =0 MCF 24+942+41.7=0.(b) 解(a)和(b),得 4=1.15 42=-4.89
8-2位移法Ⅰ——直接平衡法 （3）建立隔离体平衡方程，求基本未知量 0 M M M BA BE BC + + = 1 2 10 2 1.7 0 (a) + − = 解（a）和（b），得 1 2 = = − 1.15 4.89 MBA MBE MBC B 0 MCB M M M CB CF CD + + = MCF MCD C 1 2 2 9 41.7 0 (b) + + =