PR (2)M()=-(1-cosq) M(9 B截面处转角 PR B M(om() Rdp 4EI EⅠ (z-2)(逆时针) 0 B P/2( ) ( ) ( ) ( cos ) , ( ) ( ) ( ) ( ) 2 2 1 1 4 2 0 0 0 2 2 M PR M B M M E I R PR E I B          = − = = = −  截面处转角 d 逆时针 P / 2 M0 = 1  