Study On The Analysis Methods About The Highway Flat Steel Box Girder

With the development of transportation and urbanization in an accelerating pace, bridge will play a key role in both rail way and road traffic systems. To meet the need of fluent transportation, various innovations of bridge types, such as wide bridge with large span and super width have been constructed in the recent years in China. Of the new types of bridges, the streamline flat steel box girder has been widely used thanks to its small dead weight, large capacity of spanning in both length and breadth directions, time sparing in both factory and site works, no creeping in girder and good vibration adopting capacity so on.Under surcharge load, flat steel box girder deflect simultaneously, with nearly magnitude, in both longitudinal and lateral directions. This feature incurs that the behavior of the flat steel box girder structure is too complex to be analyzed with classical computing methods. At present, there is no convenient calculating method available for flat steel box girder analyzing. It is useful to discuss the calculating methods of flat steel box girder structure, in terms of both theory and practice.A brief history of the development of flat steel box girder structure in bridge engineering is present and its calculating methods are reviewed. Based on the sate-of-art of the theoretical methods of flat steel box girder in bridge engineering, several suggestions on analytical method are proposed for studying in great depth.According to the structure characteristic of flat steel box girder in bridge engineering, both equivalent girder beam method and orthotropic plate method are used to conduct stiffness simplifying, parameters and boundary conditions defining. As a case history, named Jinshan bridge, which is located in TEDA street in Tianjin Economic and Technology Development Region, is analyzed with bridge special-purpose finite element code during its construction period. According to the analysis results, key sections, in terms of stress and displacement, are analyzed in comparison to the results of the above two methods under various adverse load conditions. Several key sections have been instrumented and monitored during the bridge construction.The comparison results between analytical and numerical analyses, as well as between the analysis result and that of monitoring, prove that the nature of flat steel box girder structure has been well captured by both equivalent girder beam method and orthotropic plate method and the methods used in stiffness simplifying, parameters and boundary conditions defining are practical.