关键词: 连续刚构桥, 悬臂施工, 不对称变截面, 箱粱扭转变形

Abstract: Based on the dimensional theory method，the theory of shearing force flows and Prandtl'S soapfilm analogy method，formulas for calculating torsional an gle and shearing force of box beam 6f anisomerous variable section at the stage of the balanced eantilever construction were inferred．By means of the formulas ，the torsion，distortion and internal force of the box beam of Chongqing Yudong Changjiang Bridge at the stage of balanced cantilever were calculated and analysed．The calctdationval result validates that the torque which is produced because the dead load and the constructing load distribute anisomerously has few torsion an d distortion on the box beam，and that internal force on the box beam is in the controllable area．

Key words: continual rigid frame bridge, the balan ced can tilever construction, anisomerous variable section, torsion and distortion of box beam