Reseaech Of The Influence Of Boundary Conditions Change On Suspenders Tension

The half-through or through arch bridge which are widely used is a kind of new type of bridge.In recent years,it has been vigorously developed in our country.However,bridge collapse accidents often occur due to the failure,corrosion and fracture of suspender.As the main load-bearing component of the arch bridge,the identification of its tension has important research significance.The vibration method is the most commonly used method to measure the suspender tension in engineering at present.The natural vibration frequency of the suspender is measured on site,and the tension of the suspender is calculated indirectly according to the theoretical formula.In actual engineering,the boundary conditions may be in a state of constant change due to the influence of external environment and other factors,which will cause errors to the suspender tension test.Taking Liu Jiang Yellow River Bridge in Zhengzhou as the research background,the factors affecting suspender tension test and the influence of two boundary conditions,arch rib roll and bridge deck vibration,on the tension test are studied in the paper.The main research contents and results of this paper are as follows:(1)The classification and structure of arch bridge suspender are summarized;From the perspectives of working principle,,application scope,advantages and disadvantages,the current commonly used suspender tension testing methods are compared and analyzed.Based on the energy method,the theoretical calculation formulas of the string model and the beam model are derived.It is considered that the bending stiffness should be considered and the beam model should be used to calculate the tension of the suspension rods in the actual engineering arch bridge.(2)The influencing factors of the suspender tension test are analyzed.Taking Zhengzhou Liujiang Yellow River Bridge as the research background,the stiffness,boundary conditions and equivalent calculated lengths of the suspender with different lengths are identified.(3)Based on the finite element method,ABAQUS is used to establish the arch bridge suspender model.By changing the end face node displacement of the suspender,the influence of dynamic boundary conditions on the suspender tension,such as arch rib roll,bridge deck vibration and simultaneous action of two boundary conditions,are simulated.It is found that the rib heeling has a significant effect on the nominal maximum tension of the suspender.The bridge deck vibration has influence on the natural vibration frequency and nominal maximum tension of the suspender.By summarizing the influence laws of the two boundary conditions on the average tension and nominal maximum tension,the influence coefficients of the arch rib roll and the bridge deck vibration on the short,medium and long suspenders are given respectively.The example shows that,the tension error of the derrick is smaller considering the influence coefficient of dynamic boundary condition.