Force Analysis And Research Of Key Problems In The Incremental Launching Construction Of Bridge

Incremental launching method was extended to practical application rapidly for the following advantages, high industrialization, less land occupation, repeated usage and briefness of equipment, without traffic interruption, well structural integrity, quietness, rapid construction speed. And it is competitive in the construction of medium span bridges. With the continuously innovation of the equipment and the expanding scope of application, new problems were occurred inevitably. Combined the reading of related literatures and the field monitoring of incremental launching construction, this paper mainly aims at the study of the key problems and local force analysis close to the bearing area during construction.The classification of incremental launching was reviewed, form different viewpoints, and temporary facilities and problems facing the construction was discussed, so as to form an overall understanding about incremental launching. The force analysis of main girder in incremental launching construction was carried out by the combination of classical analytic method and numerical solution method, the analytical expression was obtained by classical analytic method. And reaction of temporary pier, internal force and displacement of girder in the construction of ShaoXingBinHai Bridge was analyzed by bar system FEM, parameter analysis was done to reveal the effect on the construction from the changing of elastic of bearing and lifting values of lifting jack. Using numerical analysis that was based on the analytical expression have been obtained, rational design about nose girder, reasonable connection mode of nose-main girder, and the control principle was put forward. Reasons and influences according to the disengaging of girder body above the incremental launching platform were analyzed. Solutions and improvement measures about the disengaging was put forward, in order to guide construction. Beam-Shell-Solid-Contact finite element model was built by ANSYS to analysis local structural behavior close to bearing area, inhomogeneous distribution of contacting reaction force, stress distribution of elastic layer on the incremental launching equipment, effects on the incremental launching from changing of elastic modulus of the elastic layer, influence of lateral displacement. The numerical results are in good agreement with the measured data. The simplified calculation formula was proposed according to the local force distribution of the steel box girder, in order to give a good reference for similar bridges.