Research On Restriction Measures For Rigid Slender Suspenders Of Long Span Steel Truss Arch Bridge With Wind Action

With the booming development in transportation, a large number of High-speed railways are constructed in China. Long span bridges, as the controllable engineering for crossing rivers and natural chasm, appeared in abundance accordingly. More and more steel truss arch bridges are erected in railway construction as to their relatively greater stiffness. However, the characteristics of the slender suspender of long span steel truss bridge is more sensitive to the wind action, which is prone to occur wind-induced vibration. As a consequence, there is remarkable significance to adopt reasonable restriction measures for the bridge operational safety.In this thesis, taking a bridge in Beijing-Shanghai express railway as the project example, it studies the restriction measures for stiffening slender suspender, including following aspects:(1) This thesis is giving a summary of the history of steel arch bridges and the wind destroied arch bridges at home and abroad, which briefly introduces the static and dynamic wind effects on bridge structures, the theory of galloping and vortex-induced vibration of suspenders, and the current research situation in structure restriction measures.(2) The structural dynamic characteristics of the bridge are analyzed by using ANSYS to build the finite element model, and the longest suspender's frequencies are figured out with the segmental model on the basis of finite element theory. There is theory formula given to calculate the longest suspender's frequencies.(3) Wind tunnel test and theory analysis indicate the probability of galloping and vortex-induced vibration to the longest suspender. The wind-induced vibration influencing factors are analyzed and summarized. Then restriction measures are discussed such as implementing the active control methods, changing the aerodynamic shape, installing tuned mass damper (TMD), and setting longitudinal rod, of which the effects of vibration reduction are researched followed. Analysis results show that each measure can partly decrease the wind-induced vibration, which is instructive to the design of the similar suspender structure bridge in the future.