Analysis of Force Effect of Long Span Hybrid Structure of Continuous Rigid-Frame and Flexible Arch

To study the force effect of the long span hybrid structure of continuous rigid-frame and flexible arch,the Yichang Changjiang River Bridge on Yichang-Wanzhou Railway was cited as example.On the basis of summarization of the characteristics of such type of the structure system,the analysis software Bridge Doctor was used to establish the planar finite element model for the whole bridge of the bridge,the vertical uniform load(the second phase dead load) was applied to the deck of the whole bridge and the distribution of internal forces,vertical load and midspan section bending moment of the arch and girder of the bridge was analyzed.The structural internal forces of the bridge under the action of static and dynamic loads were compared to those of a continuous rigid-frame bridge having completely the same span compositions and sectional dimensions and the effect of the hybrid structure of the arch and girder was analyzed.The results of the analysis demonstrate that under the action of the vertical uniform load,the increase of the hanger axial forces in the range of the midspan of the hybrid structure of the continuous rigid-frame and flexible arch is great,most of the total bending moment of the midspan section has been transferred to the compression of the arch ribs and to the tensile force of the main girder.In comparison to the continuous rigid-frame bridge,the bending moment of the main girder of the hybrid structure under the action of live load is considerably reduced,the structural rigidity is greatly increased and the function of the flexible arch is evident.