Seismic analysis of a 3-span half-through CFST arch bridge

A 3-span half-through CFST arch bridge is analyzed to obtain the seismic behaviour. The CFST arch ribs are converted into one material according to ‘Unified Theory'. The modal characteristic is analyzed,and the natural frequency and vibration form are obtained. The dynamic time-history analysis which adopts the Rayleigh damping is carried out under seismic fortification intensity and barely occurred earthquake. The max. internal forces and deformation are obtained under different acceleration peak value. The results demonstrate: the stiffness out of the arch ribs plane is smaller,and the vibration and deformation out of the plane are mainly observed under earthquake; the internal forces at the end of the arch rib are commonly larger than those at the top of the arch rib; the max. internal forces must be determined by several different situations; the seismic behavior of the CFST arch bridge is excellent,which can accord with the strength and ductility limits under normal and barely earthquake action in the codes.