Maochaojie Bridge with a main span of 368 m is a concretefilled steel tubular arc bridge. In this paper

a 3dimensional model for the bridge is established. Based on the model and the dynamical equation of MDOF structural system

model analysis and seismic response spectrum analysis are carried out by use of CQC

a vibration combination method and SRSS

a space combination method. The effects of primary structural factors on seismic response is studied. Analytical results are as follows: 1.The maximum seismic stress of the concretefilled steel tubular arc bridge appears in arc buttress; 2.If inplaneeffect is considered only

the structure order is affected lesser by transverse earthquake input. But because the firstorder vibration shape is the main arc and the bridge deck crosses the bridge symmetrically

the outplaneeffect by transverse earthquake input is very important to the structure and should not be neglected in bridge design; 3.The structure is also influenced greatly by vertical earthquake input. Moreover

seismic stress in some parts of the bridge is dominated by this kind of earthquake input

to which attention should be paid in bridge design; 4.Compared with other load conditions

the seismic stress is smaller and does not dominate the bridge design; The results obtained in this paper possess reference values for seismic resistance design of large span concretefilled steel tubular arc bridge.