Study On Static And Dynamic Characteristics Of Super Long Span Steel Tubular Concrete Arch Bridge With Stiffened Frame

In recent years,with its many advantages such as good mechanical properties and convenient construction,the stiff skeleton steel pipe concrete arch bridge has been widely used.The research of this paper is based on the construction plan,construction process analysis,static characteristics,and dynamic characteristics of a concrete CFST arch bridge on the Zhengwan Line.The main research contents and achievements are as follows:(1)Briefly discusses the development of the concrete-filled steel tubular stiffening skeleton bridge and its structural characteristics.It analyzes the force characteristics of the concrete-filled steel tubular stiff frame bridge and proposes the content of this paper.(2)Discussed the mechanical properties of concrete-filled steel tubular stiffeners,and introduced the calculation theory of the bearing capacity of concrete-filled tubular stiffeners in detail.A brief summary of the most commonly used construction methods for concrete-filled CFST arch bridges is given and the characteristics and application of each method are illustrated.(3)Combined with the example of a large concrete-filled steel tube stiff skeleton arch bridge on the Zhengwan Line,the Midas Civil finite element model was established,and a construction scheme was proposed for the type of bridge and combined with the terrain.Using software to simulate the construction process,the stress state in the key construction phase and the deformation of the main arch circle in each phase were obtained,providing a theoretical basis for construction monitoring.(4)The stress condition of the main arch ring and the main girder of the arch bridge is analyzed in detail,and the influence of different factors on the stress of the main arch is analyzed.On the basis of the existing research,the change of the height of the pier top is analyzed by the temperature deformation and the shrinkage and creep.The bearing settlement makes the internal force of the bridge redistributed.In the finite element software,the bearing settlement group function is used to simulate the change of pier top height,and the internal force variation of the main girder is obtained.(5)The first ten natural vibration characteristics of the stiff skeleton CFST arch bridge are analyzed and calculated,and the seismic performance of the bridge is analyzed by the time-history analysis method.In order to evaluate the state of the high-speed railway train passing the bridge,a vehicle-bridge coupled dynamic analysis was performed on the bridge to verify the safety of the train.And analyzed the dynamic response of the bridge under different vehicle models and different speeds,and consider the temperature effect + shrinkage and creep effect on the vehicle-bridge coupling.The results show that the effect of temperature difference and the residual deformation of concrete belong to the long-wave track irregularity,and the impact on the dynamic response of the bridge is negligible.With the increase of the speed of the same type of vehicle,the impact effect on the bridge becomes more and more obvious.Different types of vehicles have different dynamical performances due to the vehicle itself,and the impact on the dynamics of the bridge is not the same.The impact of the ICE3 EMU on the bridge is relatively small.