B截面转角 AB: M(r)=Ar aM 0 aM aM BC: M(x)=Fa+ Fx+MraMS F BFa (a+x)×lax 2El 4EⅠ 3-8(b) AB相对线位移 M(r)=Fr aM OF Fa am a M(x)= 2F2 F F 7Fa 2 x×xax+ El I2EI C截面相对转角 aM M(x)=Fx+m om fa O M(x) m oFa 6=2 x×1dx+ E Fa xld 4EⅠB 截面转角 ( ) 4 3 ( ) 1 2 : ( ) , 1 : ( ) , 0 2 0  = +  =  =   = + + =   =  EI Fa a x dx EI F M M BC M x Fa Fx M M M AB M x Fx l x f f f 3-8(b) AB 相对线位移： EI Fa dx Fa a x xdx EI F a F Fa M M x x F M M x Fx a a A B 12 7 2 2 2 2 , 2 ( ) ( ) , 3 0 2 0 =       =   +  =   = =   =   C 截面相对转角： EI Fa dx Fa x dx EI F m M m Fa M x m M M x Fx m a a 4 5 1 2 2 1 , 1 2 ( ) ( ) , 1 2 0 2 0 =      =   +  =   = + =   = +   