Research On The Key Technology In Construction Control Of Multi-span Continuous Beam Bridge

With the development of the Cantilever construction technique, the pre-stressed concrete continuous beam bridges get unprecedented development. Especially, with the development and application of the large-deformation expansion joint and large-displacernent rubber bearing, the deapening Of understanding about the shrinkage and creep of concrete, Stress in closure and structure system transform, longitudi nal brake force, pre-camber and deformati on, the continuous bridges tend to be design into long connected continuous girder and multi-spanned ones to exert its Superiority. At the same time, during the construction of the continuous beam bridges, the internal force and deformation will change when the main beam extends and the system transforms because of dosure construction and removing the temporary fixation, moreover, some uncertain factors affect the internal force and deformation of the structure,. such as temporary load, the change of temperature. So it will cost us more attention to insure the internal force and deformation to accord the quality and the line-shape of the completed bridge with the design.In construction control, the key technology mainly includes the structure computation and the error adjustment. The key of structure computation is to ensure the veracity of its result; the key of error adjustment is to confirm the elevati on of the formwork according to the deflections that are collected in construction, so that the configuration of the completed bridge conforms to the goal. The artide focus mainly on the influence of temporary fixation to deflection and the using of GNNM(1,1) model in constructi on control of multi-span conti nuous beam bridge.With Dan Jiang Kou bridge for Southtonorth water transfer project construction as an example, the deflection is calculated in cantilever construction stages & structure "T" to structure "â…¡" stages under the influence of temporary fixation, and the deflection is compared and analyzed with that are collected in construction. The article set forth the law of temporary fixation influence degree to the deflection in different construction stages, put forward the calculation method of elastic support stiffness, and is of certain reference to the control of deflection error in mul ti-span continuous beam bridge constructi on.At the same time, The article carries on the introduction to the grey system and neural network, and establishes GNNM(1,1) model base on grey -neural network theory due to the construction control of Dan Jiang Kou bridge for Southtonorth water transfer project. The GNNM(1,1) model is used to forecast the elevation of the formwork, and the result is satisfied.The research indicates that it is valid to carry on the structure computation with the elastic support rigidity when boundary condition is considered, and the grey -neural network theory could be used to construction control of the pre-stressed concrete continuous beam bridges.