用虚位移原理求内力的问题 1)求截面C的弯矩 2)求截面C的剪力 ↓↓4↓↓↓↓↓4↓↓↓↓4↓ ↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓ △ Q M(x+/)-ma=0 O(a0+b0)+a ydx=0 △△ △ =0Q·10+qa0·a-q·b6.·b=0 b b b b-a q=q +6 I2021/2/21 9 用虚位移原理求内力的问题 1）求截面C的弯矩 m a b c l m a b l Mc Mc   Mc ( +  )− m = 0 = 0   −       +  a m a b M c c c c l b m a b b Mc m = +  = a b c l q a b l C QC    QC q ( )  + +   = l Qc a b q y dx 0   0 0 2 1 2 1 Qc l + q  a a − q  b b =       = − − = a l q q l b a Qc 2 2 2 2 2）求截面C的剪力