Dynamic Performance Improvement For Steel-Tube Confined Concrete Arch Bridge

In recent years, as a new-type bridge, concrete-filled steel tubular (CFST) arch bridge has been deeply developed in our country, for its merits and its agreement with the actual situation of bridge construction inland. The importance of dynamic behaviors in this kind of bridge also stands out increasingly.Moving vehicle load is the main type of load form acting on highway bridge, the performance and service life of a bridge depends not only on the static performance but also on the dynamic performance under moving vehicle loads more. Concrete-filled steel tubular arch bridge has characteristics such as small deadweight, high strength and strong ability to resist deformation. But if the composing, rigidity, connection style, arrangement form of each member is not designed reasonably, serious dynamic problem may be caused although the static strength can fulfill requirement, the moving vehicles may bring large vibration to the bridge.With the case of Yilan Mudanjiang bridge in Ha-Tong Highway, the bridge space finite-element models of eight structure combined forms are constructed using the large-scale finite-element software—Ansys, the dynamical performance of the structure is analyzed using the functions of mode analysis and instant analysis. In the instant analysis, the even-speed moving constant force is added on the bridge deck to simulate the forced vibration of bridge by vehicles. Under different structure united forms, the bridge is forced to vibrate. The vertical and horizontal displacement and the time progress curve of acceleration answering on the section of middle span and vault are got; and the dynamic internal force of vault and L/4 arch rib, and impact coefficient of bridge deck middle span and L/4 span; and the characteristics of the different structure type bridges are contrasted. Aiming at the deficiency on working capability of this bridge, the methods of reconstructing the dynamic capability are put forward. This can be a theoretic reference of great span middle-supported concrete-filled steel tubular arch bridge on dynamic characteristic improvement.