The Research Of Shear Lag Effect On Aqueduct Bridge

The aqueduct-bridges are the elevated hydraulic structures, which link cannel and cross over river, valley and road. They are very the important lifeline projects. Multi-cell pre-stressed concrete box girders have been widely used in aqueduct-bridges in South-to-North Water Conveying Project. As one kind of box girder, shear lag effects will happen on these aqueduct-bridges. The effect of shear lag may cause stress concentration and affect the security or serviceability of the structures. In the 1970s-1980s, some country scholars paid attention to shear lag problems due to neglecting shear lag effect which had caused several bridges damaged. At present no research on shear lag effect of aqueduct-bridge appears in the public literatures. In this dissertation, the shear lag effect is studied about the aqueduct-bridges. The main contents are the followings.The applicability and limitation of current theories and methods analyzed in the shear lag effect of box girder are summarized and discussed. By considering the deformation properties and assuming the longitudinal displacement functions of the aqueduct-bridge, the calculation formula of shear lag effect of aqueduct-bridge was inferred by variational principle according to the principle of minimum potential energy, and the shear lag effects of simply supported aqueduct-bridge and continuous aqueduct-bridge were analyzed.The finite element method using in the analysis of aqueduct-bridges is introduced. The application of shell element and solid element in analyzing the aqueduct-bridge is discussed, and the shell element is a good kind element and sufficient for the precision in calculation.By using the finite element method (ANSYS code), the shear lag effects of simply-supported and continuous beams under the loads of the water press and the deadweight are analyzed. The various effective factors of the shear lag on aqueduct -bridge are analyzed and discussed. According to the results of calculations, the width/span ratio, load forms, and boundary conditions are the main factors which...