The Study On Mechanical Behavior Of Curved Cable-Stayed Bridge With Steel Box Girder

Curved cable-stayed bridge,a traditional cable-stayed bridge,which designed on curved line to adapt to the line trend.It has good landscape and line adaptability,and plays an important role in the construction of urban and mountain traffic.In addition to the characteristics of curved girder bridges and cable-stayed bridges,curved cable-stayed bridges also have a large transverse bending effect on the main girder,and the main tower has changed from the original bending and bending member to a combined bending and torsion deformation member.The reason is that the spatial effect of the cable of the cable-stayed bridge is enhanced.Curved cable-stayed bridges can improve the mechanical characteristics of the curved main beam by adjusting the difference between the inner and outer cable forces,and offset most of the coupling torque caused by vertical dead load.Therefore,compared with traditional cable-stayed bridges,curved cable-stayed bridges have a strong spatial effect.The main beams and towers are both spatial elements,which cannot be simplified according to the plane structure when calculating.This paper relies on the curved steel box girder cable-stayed bridge of the Xigu Chaijiaxia Yellow River Bridge in Lanzhou and uses the finite element analysis software MIDAS to study the static performance of the curved steel box girder cable-stayed bridge.At the same time,in order to study the influence of the radius of the curve on the static characteristics of the cable-stayed bridge,a simplified model of the cable-stayed bridge with different curve radii was established,and the internal force variation of the cable-stayed bridge with different curve radii was studied.Finally,the control differential equation of the separated steel box girder is derived,and the shear lag effect is studied.The main research contents of this article are as follows:(1)This paper introduces the calculation theory of internal force and displacement of curved girder bridge based on simple torsion theory.By deriving the differential equation between displacement(linear displacement and torsional angle displacement)and external load of curved girder bridge,the internal force and displacement of curved girder bridge and its unique combined effect of bending and torsion are analyzed,so as to analyze the static characteristics of curved cable-stayed bridge;(2)Based on MIDAS civil and Midas FEA platform,the whole and part numerical models of Chaijiaxia Yellow River Bridge under construction are established respectively.Through the analysis of the whole and part stress of the curved cable-stayed bridge,the stress characteristics of the case bridge in the completion stage are studied;(3)In this paper,the simplified cable-stayed bridge model is analyzed numerically,the mechanical properties of the cable-stayed bridge under different curve radii are studied and analyzed,the influence of curve radii on the static characteristics of the bridge is explored,and the calculation results are explained in combination with the curve beam analysis theory,and the internal force variation law of the cable-stayed bridge and the problems that should be paid attention to in the design are further explored;(4)Based on MIDAS FEA platform,a numerical analysis model is established to analyze the shear lag effect of curved steel box girder.The shear lag effect of curved steel box girder under uniform load and torque is analyzed.In this paper,the static characteristics of steel box girder curved cable-stayed bridge are analyzed and studied,the spatial mechanical characteristics of curved cable-stayed bridge are determined,and the curve radius which has great influence on its mechanical characteristics is analyzed and studied,and some statics change rules of this type of bridge are summarized,which provides some reference for the design of this kind of bridge in the future.