Span Prestressed Concrete Continuous Box Girder Bridge Shear Lag Analysis

Shear lag effect is a much complicated issue of research, because of the diversity of the influencing factors, although a number of research results have been achieved by the domestic and foreign scholars, the existing theories and methods are more or less subjected to certain restrictions, there are also some common problems. This paper concentrate on the following studies:(1) An overview of domestic and foreign box shear lag effect research methods is conducted. Then the detailed energy variational method for solving box shear lag effect and the finite element method of numerical analysis were compared, the results show that the use of finite element numerical method of analysis of shear lag effect is feasible and can be more flexible to adapt to different forms of box-section, load form and support mode and so on.(2) With Liuyang River large span highth-varied continuous girder bridge as the project background, by use of plane beam program (Dr. Bridges) and the space finite element program (ANSYS) to establish the planar and spatial finite element model, under the dead load and dead load plus temperature load, the shear lag effect were analyzed numerically.(3) The influences of the factors such as the thickness of the roof box, the horizontal width of box, box length in cantilever box girder to the shear lag effect are discussed. Through the analysis of comparison, the thickness of the roof box, box horizontal width, the length of box girder cantilever have different influences on the shear lag effect, the thickness of the roof box is of most importance ,while the length of the box girder cantilever is of the least.