The Mechanical Properties Research On Special-shaped Cable Tower Of Cable-stayed Bridge

The status of cable-stayed bridge especially its high bridge tower increases with each passing day at urban landmark architecture and human landscape.Designers pay more and more attention to aesthetic value and innovative modeling of bridge tower while they optimize their mechanical performance.As a result,there are more and more special-shaped cable towers,which present obvious space characteristis.The specifications is based on the ways of beam elements rather than solid elements to evaluate the force performance of bridge tower.At the same time,it is differcult to determine their advantages and disadvantages.Therefore,the research on the difference between beam element and solid element,and the reasons for the difference have great significance.Taking the FuJiangRiver whose bridge tower looks like a vase as the engineering background,contrast the difference on the the analysis of mechanical properties.The main work is as follows:(1)Discuss the influnce of grid type and grid size on the accuracy in the modeling process.The results show that the higher-order tetrahedron unit and rule hexahedral unit is affected smaller by the grid size than the low-order tetrahedron unit on displacement and stress while establishing the model.(2)From the single structure to the bridge tower,the article compares the difference and cause between the beam element based on MIDAS/Civil and solid element based on MIDAS/FEA in single structure and special-shaped bridge tower.Results result show that the beam element and solid element can reasonably simulate the overall stress of the bridge tower,but beam element cannot accurately simulate stress distribution of hollow beam or column along the width direction.Besides,both the results of relative difference is big except for the curve beam.However,the absolute difference is small.Therfore,the desiginers should improve its security when they use beam element to build a model whose column intersects curve beam.At the same time,the main cause of beam element and solid element lies in the shear lag,beam-column effect,stress concentration and the position of the equivalent load.(3)The article respectively uses the software of MIDAS/Civil and MIDAS/FEA to build the model of bridge tower with space beam element and elaborate solid element to compare and analyze the force to unify the two kinds of modeling.Results show that the conventional modeling cannot achieve the reunification of the two results completely.the paper unifiing the two styles results from a variety of modeling method and the influence factors,it concluds that,in the process of building model with beam element,the area where beam and column intersect should take different coefficient of rigid zone according to different angle.(4)Bulid the elaborate solid element of the actual bridge tower,mainly analyzes the force situation under the two working conditions of dead load and dead load plusing live load,and provide reference for the construction of the bridge tower or the same type bridge tower.