3-7(c 水平位移 AB: M(x)=Fr aM aM BC: M(x)=Fa+ Fx+Fx OF F (a+x)xc ra= 5Fa3 2EⅠ I2EI 垂直位移 AB: M(x)=Fr o aF aM BC: M(x)=Fa+Fx aF F Fx.xdx+ El 26/(a+xa13F3 LeL A截面转角 AB: M(x)=Fx+M aM aM aM BC: M(x=Fa+ Fx+M iFa Fx×lax+ (a+x)×lax El EI 4EⅠ3-7(c) 水平位移 ( ) 12 5 ( ) 2 : ( ) , : ( ) , 0 3 0  = + = → =   = + + =   =  EI Fa a x xdx EI F x F M BC M x Fa Fx F x F M AB M x Fx l x f f f 垂直位移 ( ) 12 13 ( ) 2 . : ( ) ' , : ( ) , 3 0 0  = + + =  =   = + =   =   EI Fa a x adx EI F Fx xdx EI F a F M BC M x Fa F x x F M AB M x Fx l l x A 截面转角 ( ) 4 5 ( ) 1 2 1 : ( ) , 1 : ( ) , 1 2 0 0  =  + +  =  =   = + + =   = +   EI Fa a x dx EI F Fx dx EI F M M BC M x Fa Fx M M M AB M x Fx M l l x f f f f