Study On Spatial Mechanical Behavior Of Cable-stayed Bridge With Single Tower Composite Beam

With the development of transportation industry,the calculation theory and the modern construction technology,the span of modern cable-stayed bridge is getting wider,and its structure stress is getting more complicated with a more obvious spatial effect.Bridge accidents in recent decades show the differences between the results of overall analysis on the entire bridge and the true mechanical behavior of the bridge structure due to the neglect of the partial construction of the structure.Some parts of the cable-stayed bridge have some problems such as stress concentration,shear lag and stress diffusion,while these parts are often the keys to the quality of the engineering for this kind of structure.Therefore,it is necessary to make a refine analysis focusing partial finite elements of these parts on basis of the overall analysis on the whole bridge,so as to accurately know the stress condition.Taking Aojiang No.4 Bridge as the specific engineering background,with the purpose to healthily monitor the long-span cable-stayed bridge in steel-concrete composite beam,this paper adopts the finite element principle to study its spatial mechanical behavior.The main work is as follows:(1)Through the establishment of the full-bridge spatial finite element model,this paper studies the overall spatial mechanical behavior of the cable-stayed bridge in single tower steel-concrete composite beam.It mainly analyzes the internal force,stress and the deformation of the structure under the condition such as the dead load,vehicle,temperature and wind load;besides,the dead load during the initial period of bridge formation,and the shrinkage and creep of the concrete during the later period of bridge formation.(2)On the basis of the overall analysis,it identifies the most unfavorable section ofthe beam under the most unfavorable working condition;based on the multi-scale principle,it establishes a refine and partial model of the finite elements in this section of the beam;meanwhile,studies the spatial stress distribution and the mechanism of mutual mechanical transmission of the concrete bridge deck,the girders in longitude and latitude,and the stiffening system of longitudinal and latitudinal girders to provide basis for the refinement design.(3)According to the actual construction sequences of Aojiang No.4 Bridge,the whole construction process is divided into 128 construction stages.With the forward analysis to simulate the construction process,it analyzes the static behavior and internal force distribution of each component in different construction stages to discusses the mechanism of internal force evolution of key parts in the bridge and the influence of cable tension on the structural stress and deformation during the whole construction process;thus to provide references for the guidance of the construction.