Study On Method Of Calculation And Detection Of An Irregular Box Girder Of Qianjin Overpass In Changchun

With the development of transport and the increasing level of bridge construction, the conventional bridge cannot meet requirements for traffic diversion in the large-scale interchange project. In contrast, because of flexible structure, irregular box girder can better adapt to changes in traffic flow, and it has become an important part of the major interchange hub.From the view of structure, there is a clear difference between irregular box bridges and conventional bridges. The rules of the conventional bridge structure is regular and constraint is very simple, the majority of their calculation can be simplified as plane structure; but irregular box bridges often use non-symmetrical structure, the spacing of the main beam are not equal, the constraints are complex. Plane model does not reflect the characteristics of its structure. From the point of the characteristics of stress, load distribution in conventional bridge is simple, In the most adverse loads of the main beam, usually, only consider the effect of deformation that caused by internal forces, and the position of the main beam in space between symmetric and assume. Most unfavorable load also has symmetric relation; and shaped bridge under load than bending deformation, but often accompanying with torsional deformation. Comparing the stress state with the conventional bridges, the irregular box bridges are more complex.Currently, the profiled studies method of the shaped bridge at home and abroad is in the testing stage of exploration, Not like the conventional bridge have systematic analysis of the formation of theory and calculation method. Research for this paper, the finite element analysis of bridge approach on the basis of a systematic description, select the Forward Avenue overpass Changchun shaped rregular box girder bridge as the research object, the specific element model describes the spatial entity and the shear beam model grid method process. And by comparing the weight of a typical load cases and under the vehicle loading conditions, the results of two models to verify the calculated the bridge accuracy of shear beam grid shaped box girder.Since the bridge load test can not only objective, accurate and comprehensive evaluate the bridge's construction quality and working conditions, but also can provide important technical information for the completion and acceptance and the future conservation of the theory of special-shaped bridge. Therefore, this article profiled research the bridge into the bridge of detection for the corresponding, design the way forward Avenue left Road shaped box girder bridge static and dynamic test program. Pre-set by the bridge construction phase within the main beam vibrating wire strain gauge on the strain tested, the use of displacement gauges and dial indicator on the deflection test. And static and dynamic load test data and finite element simulation results were analyzed, providing an objective evaluation on overpass carrying capacity of the completion phase of the forward Avenue bridge.