Dynamic Of Long-Span Concrete-Filled Steel Tubular Arch Bridge

In recent years, our country economy stability increases and the scientific technology develops quickly, more investment is put into the fundamental facilities, we accomplish a lot of great construction of bridges and a large improvement also be made in bridge construction technology. With the high capacity, strong spanning abiltiy, good seismic behavior and convenience of construction, Concrete-filled steel tubular (CFST) arch bridge develops rapidly and is a quickest-developing structure of bridge, which was built since 1990. With the continuous development and mature of CFST structural theory, CFST arch bridges are developing in the direction of more large-span and more large scale. At the same time, the application area and range are expanding continuously, and the largest span of CFST arch bridges which have been built has exceeded 450m at the present time. With the adaptable of CFST arch bridge's rapid developing, much favorable work has been done about the theory research of CFST arch bridge, but these fall behind its development.In this paper, the dynamical basic theory of CFST arch bridge is studied. U .L formulation-based of finitude deformation in nonlinear continuous mechanics, the three-dimensional nonlinear curved beam element with considering large displacement and large rotation is presented in this study. On the base of this, the finite element program which can be used for the dynamical analysis of CFST arch bridge is complied. Using this program, the free vibration and seismic response of Hunan Nanxian Maocaojie Bridge which is being built, are analyzed. The effect of different structural parameters on natural frequency and seismic response is examined; at the same time, the effect of other factors on seismic response is also investigated. The specific research mainly included several aspects as follows:1. Applying the nonlinear geometrical differential Frenet-Serret formulation and Hamilton principle, the motion of equations of arch are derived, which is the foundation of nonlinear dynamic theories of the elastic arch. And the Liapunove-Schmidt method is used to study the dynamic buckling of a shallow arch. An approximate analytical expression of dynamic critical buckling load amplitude of a elastic arch can be attained.2. The dynamical increment equation which is based on finitely deformation in nonlinear continuous mechanics, is deduced by virtual work principle. At the same time, the dynamical increment equation is overwritten into finite element increment format by using the basic principle of finite element. The dynamical equations of long-span CFST arch bridge which considering damp and exterior load are also deduced by...