Mechanics Characteristics Analysis On Long-span Railway Extradosed Cable-stayed Bridge

Extradosed Cable Stayed bridge is with strong competitiveness in long-span railway concrete bridge whose span varies from 100 m to 200 m.Cable-stayed bridge belongs to high statically indeterminate structural system.The structural system and the calculation method of the bridge are very complicated.The mechanical characteristics of Extradosed Cable Stayed Bridge,from construction stage to finished stage,have been constantly changing.The mechanical characteristics vary with different construction methods.Therefore,grasping the rational construction methods and mechanical characteristics from the beginning is the prerequisite of buiding a reasonable bridge.The qualitative judgment based on the previous experience in bridge construction as well as the force conditions in each period of operation stage is not enough.To establish precise simulation models which can simulate the data of various stages to judge whether the internal force state and the deformation conform to the standard is needed.When applying the models to the construction stage,real-time analysis and prediction of the bridge can be done.Problems can arise correction immediately.With the existing software,the precise analysis of Extradosed cable-stayed Bridge from the construction phase to the operational phase can be obtained as well.In this paper,the main bridge of Dongping channel,which is a long-span railway Extradosed cable-stayed bridge,has been considered as the engineering background.The finite element model of the full-bridge is established through a dedicated bridge finite element analysis software Midas Civil.Thus,an associated simulation analysis has been done on the basis of this model.In the beginning of this paper,the origin and development of Extradosed cable stayed bridge and long-span railway Extradosed cable-stayed bridge is presented.Besides,a complete mechanical analysis and designing composite of the bridge building process from the construction phase to the operational phase has been carriedout according to its design drawings.Analysis have shown that the design of main bridge is reasonable,which meets the current regulatory requirements.The mechanical characteristics of each stage of Extradosed cable stayed bridge are made clear through the analysis results,which provides technical support for the subsequent construction monitoring as well.Afterwards,the sensitivity analysis of various parameters which influence the internal force and deformation in the construction phase of bridge have also been presented.The main beam weight,elastic modulus,prestressing loss,temperature changes and other key sensitivity parameters have been calculated.The sensitivity analysis results of these parameters on the main beam axial force,bending moment,linear,stay cables' internal forces,can also provide a theoretical basis for the construction phase of the bridge.Finally,the temperature effects on internal force and deformation of the railway bridge during the operational phase have been researched,which privides some reference for the design,operational assessment theory and driving comfort studies of the long-span railway Extradosed cable-stayed bridge.Then,the mechanism of the temperature influence on the bridge is discussed.Valuable conclusions have been carried out about the temperature difference between Cable and tower beam,the temperature change of the whole,the positive and negative temperature difference in the main beam and the related combination effects in influencing internal forces and deformation of the bridge,on the basis of related design theories,engineering experience and finite element analysis.