Static And Dynamic Characteristics Analysis Of Double-arch-pylon Cable-stayed Bridge

The style of pylon of cable stayed bridge becomes diversified.Double-arch-pylon cable-stayed bridge is a new kind of bridge which uses two arch pylons in its longitudinal direction.The lateral braces and vertical cables are used to connect the four arch pylons as a whole.The paper takes Keji Third Road Bridge which is being built in Donghu New & High Technology Development Zone in Wuhan as the engineering background.The finite elment software named Midas Civil 2013 is used to analysis the bridge.The main content and conclusion of this paper is as follows.(1)The paper first review the development of cable stayed bridge,the force system,aesthetic characteristics,classification and development trend.Then the paper introduces the main characteristic of double-arch-pylon cable stayed bridge and the research focus such as optimization of cable tensions,cable fatigue,geometric nonlinearity,model updating and seismic analysis.(2)The paper introduces the static analysis method of cable stayed bridge,the dynamic property equations and the three main methods to solve these equations.Then,the paper recomend the calculations steps,advantages and disadvantages of response spectrum method and time-history method are given.(3)Ernst formula is used to correct the elastic modulus of cables,The isotropic stiffness of anti-seismic bearing is computed.The distribution of displacement,force and stress of the bridge under moving loads are given,the influence line of the key section is drawn.Also,the paper gives the distribution of force and stress of the girder,pylon and cable under the combination conditions of live load and live load combined dead load.Then,the paper analysis the impacts of structural parameters' changes on the moving load condition and dead load condition.The conclusion is that,the error is less than one percernt exept the vertical cable numbered L6 before and after correction.Stress of the components is less than material bearing limit with a certain security surplus under each working condition.The lateral braces and vertical cable can enhance the transverse and longitudinal stiffness.The dead load of girder and the stiffness of structure member both have important influence on the stressing state of the structure.(4)The multiple Ritz vector method is used to compute the modal of Keji Third Road Bridge.Then,the influence of structural parameters' changes on the modal is conducted.The structural parameters include having vertical cable or not,having lateral braces or not,the dead load and stiffness of structural member.The paper advises adopting lightweight materials,enhancing the stiffness of girder and arch pylon,using suitale rise span radio and considering all kinds of vibration mode.(5)The paper uses response spectrum method and time-history to analysis the response of earthquake on Keji Third Road Bridge.The spectrum is designed under the code.The time-histrory method uses the corrected Taff earthquake record.The each displacement of Keji Third Road Bridge is mainly affected by the each direction earthquake.The stress of girder is mainly affected by vetical earthquake.The stress of arch pylon is mainly determined by horizontal earthquake.From an overall perspective,the result computed by time-history is less than response spectrum method.The error is nearly 25 percent.