3.1 Introduction T= M Y h T2= M2 M+AM rh rh M △M △T= M=M+AM M rh △r AT V T= T=T+AT T △x4s rhus Average bond stress 土本工程学院4 4 3.1 Introduction P P M T2=T1+T T1  x M2=M1+M M1 h M T s  1 1 = 2 1 2 s s M M M T   h h +  = = h M T s    = s s s T V x h      = =  Average bond stress